Corona Renderer Forum

General Category => Gallery => Work in Progress/Tests => Topic started by: dubcat on 2016-10-10, 14:35:11

Title: dubcats secret little hideout
Post by: dubcat on 2016-10-10, 14:35:11
This will be my little hideout where I share crazy stuff and what not.

I will make a proper first post later.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2016-10-10, 14:35:24
During the Corona 1.5 Daily Build phase I was pushing/testing hard to get all the proper Blending Modes into CoronaMix.
There are three main reason for this. I will be posting two new mini guides on two of the reasons in the near future.
The third reason is procedural masking.

I've been talking to Ondra about procedural maps/masks for a couple of weeks now.
My idea is to turn Corona into a crazy ass procedural beast.

Last night I put together a proof of concept inside the material editor. It's basically Quixels dDO inside max.
Right now I'm using baked maps for Curvature, AO, ObjectSpaceNormal and Gradient. Everything else is done inside the material editor.
I've posted Mantis requests for Curvature, ObjectSpaceNormal and Gradient maps. If we ever get these maps, we only have to swap them with the baked bitmaps, and there we go.
Crazy ass mask generator inside max!

Here are the input maps.

(http://i.imgur.com/I46ZDAf.jpg)

My proof of concept mask generator that behaves like Quixels dDO.

(http://i.imgur.com/NVGozp8.png)

Out comes

(http://i.imgur.com/2w6XuMU.jpg)

(http://i.imgur.com/3cATAmS.jpg)
Title: Re: dubcats secret little hideout
Post by: Dionysios.TS on 2016-10-10, 15:17:14
oh God....
Title: Re: dubcats secret little hideout
Post by: romullus on 2016-10-10, 15:20:34
That's crazy. Nice, but crazy :] Wonder how big penalty in render time you'd get from such material setup compare it to baked maps?

Doesn't CoronaData map already has world object space normal map pass? Can't test it at the moment.

Anyway, i love procedural stuff. Insta subscribe!
Title: Re: dubcats secret little hideout
Post by: Ludvik Koutny on 2016-10-10, 16:16:18
Yep, I enjoy procedural shading too...

Aside from Romullus' question if there isn't already something you need in CoronaData map, the gradient map you mentioned, doesn't 3ds Max's gradient ramp already do that? I mean you can plug in source texture and map its luma range using that gradient.

What I am most missing for procedural shading inside 3ds Max is just a simple blur texture, that just simply blurs.
Title: Re: dubcats secret little hideout
Post by: TomG on 2016-10-10, 16:20:19
Lol on the simple blur, I was looking for that last week but could find no way to do it (wanted to blur some procedural output), so yes, that would be a useful thing!
Title: Re: dubcats secret little hideout
Post by: karnak on 2016-10-10, 17:25:18
I support this.
Consider that hero materials can be as complex as the one that dubcat posted, but for the rest of the materials I think just the curvature map can do wonders without too much penalization.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2016-10-10, 19:20:38
One of the first things I did was to test all the CoronaData maps, the position map is not the kind we want.

(http://i.imgur.com/9iCg5VZ.jpg)

Round Edge Map is almost a Curvature map. I use it as a filler curvature map every now and then, but it also masks crevices white.
I have reported this is my Curvature thread on Mantis.

(http://i.imgur.com/IsFLK9F.jpg)

The biggest problem right now is that all the default 3dsmax maps are calculating shit in linear and we need sRGB.
I'm adjusting all these maps afterwards with an Output map as a little hack.

(http://i.imgur.com/w7xTHOQ.jpg)

These functions need to be added to CoronaOutput in Photoshop form. (Reported on Mantis)
- Invert
- Gamma
- Legacy Brightness
- Legacy Contrast

We also need to split the Curvature map into 7 parts, to get full control, and then blend them back with Overlay.
To do this we need Highpass filter (There are functions out there for real time) and Gaussian Blur.

I did a 32 pass test.
Big ass procedural tree = 06:45 min
1 compiled bitmap = 01:40 min

I hope all this stuff can be bundled into one optimized map. I've already offered to make a reference sheet on how all this fits together.
If Team Corona want to tackle this map, just text me on Skype.

I made this mock up (v0.1) last night when I made the proof of concept.
It might look overwhelming, but when you load the map, all the boxes should be closed.
So if you want to work on Curvature, you open the curvature section etc.
I forgot to add master opacity for each map.

(http://i.imgur.com/edDfFzO.jpg)
Title: Re: dubcats secret little hideout
Post by: steyin on 2016-10-10, 20:50:52
I used to think that procedural maps did not tile for some reason and instead went on in random generation forever. Kind of wish they behaved like that instead.
Title: Re: dubcats secret little hideout
Post by: pokoy on 2016-10-10, 21:03:41
I have to say I'm glad some people here fall into the mad professor category - in a good way, of course - I'm awestruck, looking forward to where this could get one day.
Title: Re: dubcats secret little hideout
Post by: lacilaci on 2016-10-10, 21:27:33
Well if this is not something "in the works" now, it could be listed at least for now in "the most wanted features" poll...

Flexible procedural map even partialy substituting the likes of substance or quixel mask generators is a great added value.
Title: Re: dubcats secret little hideout
Post by: karnak on 2016-10-10, 21:56:50
How the shader graph would look like with this CoronaMaskBuilder compared to the image you posted at the beginning?
Title: Re: dubcats secret little hideout
Post by: romullus on 2016-10-10, 22:03:34
Doesn't CoronaData map already has world object space normal map pass?

One of the first things I did was to test all the CoronaData maps, the position map is not the kind we want.

I mean this:

(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=53149;image)
Title: Re: dubcats secret little hideout
Post by: dubcat on 2016-10-11, 23:15:56
I've remade the FuzzyShading map from Unreal 4.

It's using the default Unreal 4 settings, including falloffs.
There are 3 parameters you can adjust to taste. These are Core Darkness, Edge Brightness, Power.
You can either use it as in the example below, or you can make one material for the stone and one for the moss. And then blend them together with the fuzz mask.

Download link bellow.

(http://i.imgur.com/4rd4qtU.png)

I used one of the free Megascans assets to test the shader while I was building it.
I can't wait to try this shader on fabrics!

Here are some test renders, in case you don't know what all the fuzz is about. (I used the default settings).
Open the pictures in a new tab for maximum comparison satisfaction!

Normal Corona Shader

(http://i.imgur.com/dRyOLLh.jpg)

FuzzyShading Shader

(http://i.imgur.com/jd5Kl9N.jpg)

Enjoy.

How the shader graph would look like with this CoronaMaskBuilder compared to the image you posted at the beginning?
The graph and the mock up is the same :)

I mean this
It looked kinda similar, but the hotspots and falloffs didn't quite match. If this is the correct map, it needs to be adjusted a little.
Title: Re: dubcats secret little hideout
Post by: romullus on 2016-10-12, 09:57:36
I like how it kinda glows on grazing angles and in shaded areas, but transition from rock to moss doesn't look that good.

It looked kinda similar, but the hotspots and falloffs didn't quite match. If this is the correct map, it needs to be adjusted a little.

Not sure about that, but could it be due to difference in how normals are calculated in various apps? Sadly there isn't unified standart for normal shading.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2016-10-12, 19:01:20
I've ported Metallic Shading from Unreal 4.
The falloff has bright edges, dark middle and semi bright center.
In Unreal 4 you are only allowed to change the Base Color, but you can tweak the gamma inside the Pow maps for different looks.

Basic shader to show the effect

(http://i.imgur.com/kzxOlo3.jpg)

(http://i.imgur.com/wiyZ7xa.jpg)

I've also updated the Fuz shader.
- Fixed some math in the Core Darkness section.
- I realized that pow is the same as inverse gamma, so now you can adjust Power the same way as in Unreal 4.

(http://i.imgur.com/6srRnPZ.jpg)

Transition from rock to moss doesn't look that good.

This has to do with Edge Brightness, I had it at 1 during testing.
Title: Re: dubcats secret little hideout
Post by: rambambulli on 2016-10-15, 09:13:20
Professor Dubcat,I love it! I have been looking for this to hook the curvature, positionmaps, etc. to some Substances I made.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2017-02-03, 19:47:27
Megascans Studio heightmap based blending inside 3dsMax

(http://i.imgur.com/euMG6yq.jpg)

(http://i.imgur.com/OcHUT1D.jpg)

edit:
The Gamma 2.2 map is there because Output Map is linear, and we want to emulate Levels in Photoshop.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2017-02-16, 00:04:10
Edit: Bug in my auto script, will post update when it's sorted out.
Title: Re: dubcats secret little hideout
Post by: romullus on 2017-02-16, 15:10:01
I thought that after most recent changes in Corona material (PBR mode), its glosiness matches 1:1 with Vray GGX, isn't? :/
Title: Re: dubcats secret little hideout
Post by: dubcat on 2017-02-18, 02:41:13
I thought that after most recent changes in Corona material (PBR mode), its glosiness matches 1:1 with Vray GGX, isn't? :/

It should be closer, I noticed a bug in my vray script. The fstorm table is accurate. I'll wait until the table is 100% complete before I post it again.

------------------------------------------------------------

Here is a little "how to get that fStorm look in Corona" post.

I've attached a little Photoshop script that will turn your harsh Corona renders into soft fStorm renders.
This blur/sharpen effect really help sell that photorealism, when did you capture a picture with your camera and the noise was pixel perfect ? (I'm not talking about ISO 1million)

If you are using Arion to add chromatic aberration, you will already have a blur like this (- the sharpen), since this is a side effect of the R G B transform. But this Photoshop script is shifting R G B equally.
If you do an anti chromatic aberration operation in CameraRaw after Arion, you will see that your render still looks more Photorealistic after the anti chromatic aberration operation. This is because the blur that is the main ingredient.

This stuff should be included in Corona frame buffer. Go and +1 on mantis (https://corona-renderer.com/bugs)!

(http://i.imgur.com/YgEYeZ0.png)

and this is how you can emulate fStorms "Angle Affect" option in Corona

(http://i.imgur.com/8XXcYi9.png)

In fStorm the "Angle Affect" parameter goes from 0-1. After some quick testing, this looks to be the same as IOR 1.5 - 3
I've made a little improvement to the effect. You can specify a value that gets multiplied with the base glossiness. This is nice for rough materials, where you don't want the edges to be 255 glossiness.
So tweak IOR and the multiply value to taste.

This feature should be included in Corona if you ask me! I notice this effect each time I lay down, even on rough fabrics.
Next time you lie down in bed or drunk on the floor, try to look for this effect, and then go and +1 mantis (https://corona-renderer.com/bugs)!

(http://i.imgur.com/TsfxREx.png)

(http://i.imgur.com/bfKVUHm.png)

I've also attached two LUTs that emulate the default 0.3 contrast in fStorm and a 0.15 contrast version. The contrast slider in fStorm don't affect white, so it's more of a black crusher. The effect can be really strong, so you might want to tone it down.
This is 0.15 contrast

(http://i.imgur.com/D6MpgZf.png)

-1 HC in fStorm that has kinda become the standard, is 50 hc in Corona!

fStorm is caped at around 0.40 Corona glossiness. Which is a bad thing, but now you know.

Another thing that Corona is still missing that both fStorm and Vray has, is focus pick in frame buffer. +1 mantis (https://corona-renderer.com/bugs) if you are missing this feature!
You won't believe how amazing it is to build your scene. Walk around as a photographer, focus pick in frame buffer. CTRL + C, render afterwards. This is a MUST feature.

fStorm renders object with no material as default material, instead of random object color.

So there you go, if you follow these guidelines you will get that cRona look!

Don't forget to Mantis (https://corona-renderer.com/bugs), shit won't happen if you don't act! Spread the words to your friends.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2017-03-25, 02:52:35
edit:
These LUTs ship with Corona 1.6

I've been dumping cameras as LUTs for the past 6 months or so.
Here are 3 of those dumps.
Think of your renders as "linear raw" files from your camera, these LUTs do the camera processing (what your JPGs looks like in camera).
(By "linear raw" I mean (dcraw.exe -v -w -H 0 -o 1 -q 3 -4 -T), not CameraRAW/Lightroom import!)

You don't have to use them at 1 opacity. If you apply "Photographic 01" with 0.68 opacity, it mimics another camera. So feel free to experiment.

With these LUTs you can use 30 sRGB black / 210 sRGB  white in your materials, and they will look nice and contrasty in your final render.

These LUTs make your linear render look like a processed camera photo, it's up to you if you want to take it any further in CameraRAW/Lightroom. I always end up doing some kind of local processing in CameraRaw.

I want to give Juraj Talcik and Peter Guthrie credit for giving me valuable feedback while I dump these cameras (and still do). So thank you super duper mega very much!

Here are some quick test renders to show the general behavior
As you can see, they all have the same kind of contrast, but the HSL adjustments differs a lot.

(http://i.imgur.com/yjW8Zru.png)

(http://i.imgur.com/zOAU2FF.png)

(http://i.imgur.com/ftDwanp.png)

(http://i.imgur.com/LPC1Gpv.png)

What LUT is your favorite ? Did it improve your render ? Let me know ! (If you find weird color shift problems or anything like that, contact me).

edit:
Here are the render settings. These Sharpening/Blurring settings will give you that nice fStorm noise.

(http://i.imgur.com/uXlLutv.png)

edit:
Attached EV normalized versions so you don't have to reduce EV.
Title: Re: dubcats secret little hideout
Post by: pokoy on 2017-03-25, 10:39:38
This looks good! Will try next week - thanks for sharing them!
Title: Re: dubcats secret little hideout
Post by: Correntes on 2017-04-01, 21:22:11
yeah i will test it too.

will see how it compares with exact reference photo
Title: Re: dubcats secret little hideout
Post by: olotl on 2017-04-01, 21:29:25
this is a really nice thread! lut's working great - thanks a lot.
Title: Re: dubcats secret little hideout
Post by: miaz3 on 2017-04-02, 13:36:26
@dubcat :

I find it strange to use LUT that is not related to the digital depth of the image rendered ?!
If I open the LUT there is only 32,768 correction line (2 ^ 15). But if you work on a 16bit image it would take 65,536 (2 ^ 16) lines of corrections ...
So why lost the half data ?

Title: Re: dubcats secret little hideout
Post by: sebastian___ on 2017-04-02, 16:39:54
Great thread. What cameras are used for the extracted LUT ?
Title: Re: dubcats secret little hideout
Post by: Ondra on 2017-04-03, 11:18:27
@dubcat :

I find it strange to use LUT that is not related to the digital depth of the image rendered ?!
If I open the LUT there is only 32,768 correction line (2 ^ 15). But if you work on a 16bit image it would take 65,536 (2 ^ 16) lines of corrections ...
So why lost the half data ?
you are not actually losing anything, this is resolution of the mapping function, not the input data - even low-res mapping function can be used to transform high-res input data with no quality loss.

As an example: Corona VFB uses 32bit color format. If you change exposure, you are applying a transformation that could be expressed as 1 line LUT. But the output image does not lose any information

Title: Re: dubcats secret little hideout
Post by: Correntes on 2017-04-03, 11:22:20
Dubcat:

I prefer your PhotographicCurve v2  lut that you previously shared with albedos white 240  black 50 srgb corona contrast 4

30black/210white plus the luts seems to dark/contrasty and washout textures.

With the PhotographicCurve v2 setup i get an almost perfect material editor preview match up with the actually rendered.
Maybe I'm doing something wrong but this setup is a lot more predictable
Title: Re: dubcats secret little hideout
Post by: nkilar on 2017-04-03, 12:17:34
Dubcat:

I prefer your PhotographicCurve v2  lut that you previously shared with albedos white 240  black 50 srgb corona contrast 4

30black/210white plus the luts seems to dark/contrasty and washout textures.

With the PhotographicCurve v2 setup i get an almost perfect material editor preview match up with the actually rendered.
Maybe I'm doing something wrong but this setup is a lot more predictable

With white color at 240 I presume the render times have fallen of the charts (super high), right?
Title: Re: dubcats secret little hideout
Post by: miaz3 on 2017-04-03, 12:51:57
@dubcat :

I find it strange to use LUT that is not related to the digital depth of the image rendered ?!
If I open the LUT there is only 32,768 correction line (2 ^ 15). But if you work on a 16bit image it would take 65,536 (2 ^ 16) lines of corrections ...
So why lost the half data ?
you are not actually losing anything, this is resolution of the mapping function, not the input data - even low-res mapping function can be used to transform high-res input data with no quality loss.

As an example: Corona VFB uses 32bit color format. If you change exposure, you are applying a transformation that could be expressed as 1 line LUT. But the output image does not lose any information

I meant, losing half data of bit depth of the LUT, not the raw. This LUT is just like a "film look" ?!
Is not totaly matching to the raw data (eg 16 bit or 32 bit) soulder and foot curves too.
Which causes either the floor noise will be processed, or the high values will not be processed by the curve. (And vice versa).

Title: Re: dubcats secret little hideout
Post by: Correntes on 2017-04-03, 13:33:07

[/quote]

With white color at 240 I presume the render times have fallen of the charts (super high), right?
[/quote]

a little bit yeah :S

i'm still testing
Title: Re: dubcats secret little hideout
Post by: nkilar on 2017-04-03, 21:47:45


With white color at 240 I presume the render times have fallen of the charts (super high), right?
[/quote]

a little bit yeah :S

i'm still testing
[/quote]

Well if the contrast is bothering you that much maybe playing around with the filmic settings could do the trick. Then again it might not :)
Title: Re: dubcats secret little hideout
Post by: ASaarnak on 2017-04-03, 22:32:20
Thank you for sharing the LUTs :)
Title: Re: dubcats secret little hideout
Post by: dubcat on 2017-04-04, 01:12:27
I find it strange to use LUT that is not related to the digital depth of the image rendered ?!
Maybe I'll release 64 sliced versions in the future, 41+ should be enough for what you want.

What cameras are used for the extracted LUT ?
I went into my Canon/Nikon folders and selected 3 random LUTs. I got a lot of Canon 60D LUTs in there, so one of them might be 60D.

Canon cameras have this magenta Tint to them, sometimes -10 green. This happens even if you calibrate the camera as perfect as you can. We need to use the sexy Tint feature in CameraRAW to get a perfect white balance. Since I'm dumping the real deal, I left this error in there. If you notice a slight magenta shift, it's a Canon LUT 99%.

Canons best friend.

(http://i.imgur.com/VADHSTy.png)

and a big thanks to everyone else that has responded!
Title: Re: dubcats secret little hideout
Post by: Correntes on 2017-04-04, 11:23:47
Update:

I got it working and quite like the results

The 01b is the version with the luts and 210w 34b sRGB
Title: Re: dubcats secret little hideout
Post by: Rhodesy on 2017-04-04, 11:55:35
Looks cool. When you say 34b is that 34 the lowest/darkest you set a black material or have I misunderstood? I assume the 210 is the white wall level?
Title: Re: dubcats secret little hideout
Post by: Correntes on 2017-04-04, 12:00:13
yes

max white 210 sRGB
max black  34   sRGB
Title: Re: dubcats secret little hideout
Post by: Rhodesy on 2017-04-04, 13:13:02
Thanks. Good to know.
Title: Re: dubcats secret little hideout
Post by: agentdark45 on 2017-04-04, 14:47:47
Update:

I got it working and quite like the results

The 01b is the version with the luts and 210w 34b sRGB

Wow that's some difference. Are you able to post any of the post processing settings that you used in conjunction with the LUTs?
Title: Re: dubcats secret little hideout
Post by: Ondra on 2017-04-04, 14:49:50
good news, the new LUTs are now bundled with Corona installer
Title: Re: dubcats secret little hideout
Post by: Correntes on 2017-04-04, 16:49:03
Update:

I got it working and quite like the results

The 01b is the version with the luts and 210w 34b sRGB

Wow that's some difference. Are you able to post any of the post processing settings that you used in conjunction with the LUTs?

That's the beauty of it, get the exposure right, highlight compress an then I just  applied the lut at 100%, vignette, chromatic aberration, tweaked the white balance and that's it.
I do the post outside of corona due our layer workflow .

good news, the new LUTs are now bundled with Corona installer

That's wonderful news Ondra


Title: Re: dubcats secret little hideout
Post by: miaz3 on 2017-04-04, 23:42:20
Quote
Maybe I'll release 64 sliced versions in the future, 41+ should be enough for what you want.
I don't understand ?!
You deliver a LUT that was generated from 3 random LUT Canon dslr ... There is nothing logical in it ?!
Canon LUT are created for mapping Canon sensors, like arri, red et cie...
So what do not tweak a curve and that it ?! (ed: i just plot your LUT_03).

So here we've got a LUT that not mapping the raw data ? i'm not talking about 32 bit float raw, but just for this exemple 16 bit is enough.

It's that simple.
I just want to understand the interest of mapping a LUT that does not match the RAW's digital depth. Like dslr, or camera manufacturer do.


Title: Re: dubcats secret little hideout
Post by: dubcat on 2017-04-05, 00:27:31
When you take a picture with your dslr in jpg mode, the raw goes through ColorMatrix, ForwardMatrix, LookTable and ToneCurve. That's what these LUTs do.
These should be applied in a specific order, since we can only apply one LUT and not 4 LUTs after each other in order, we can't get 100% match, but it's damn close.

I always take a color checker reference picture. This way I can control if the linear raw + LUT will match the camera JPG.

Here is one of my older Canon control tests.

Linear RAW converted to sRGB.

(http://i.imgur.com/KBRQgSk.jpg)

JPG from Camera

(http://i.imgur.com/bzgowtx.jpg)

RAW + LUT (When you use dcraw to make a proper linear raw, it does not denoise the picture, so you will see noise on some colors, like purple)

(http://i.imgur.com/JWFgwRn.jpg)

Hope that helps you understand whats going on with these LUTs :)
Title: Re: dubcats secret little hideout
Post by: Hamburger on 2017-04-05, 07:48:10
THe LUT looks great for interiors, but with harsh sun + sky system it really is too much contrast and shadows are massively crushed. Does it work for anyone else?
Title: Re: dubcats secret little hideout
Post by: romullus on 2017-04-05, 10:41:30
Yes, Photographic 1 (i don't use other two) works great on many bright low contrast scenes, but are unusable on darker, more contrasty scenes, as it gives so massive contrast, that is impossible to tone down, but to reduce lut opacity to 0,2 - 0,4 at which point there's little sense to use lut at all. Also, quite often i find that it's very hard, nearly impossible to recover highlights when using dubcat's luts. It just leaves big flat dead areas with no details. But in scenes, where it works, it works just great.

By the way, when using these luts, more than ever i wish that Corona VFB would have some controls for midtones.

That is my highly unprofessional impressions.
Title: Re: dubcats secret little hideout
Post by: romullus on 2017-04-05, 17:13:24
Hey dubcat, is there a way to apply your luts in photoshop? I tried to load it through colour lookup adjustment layer and i get very different result than in Corona's VFB. Probably i'm doing something wrong here - i have little to none experience with such things.
Title: Re: dubcats secret little hideout
Post by: miaz3 on 2017-04-05, 22:17:27
@dubCat :
Thats a basic dslr workflow. Like every photographer do.
Your LUT (From dcp or icc) mapped to your dslr sensor, with everything that goes with it (Dynamic range, bit depth, ect...).
And this LUT cannot be used on a C-300 or D500, even H6D-100C...even less 35mm cmos...
It can be taken for a generic LUT, but Dynamic range, bit depth, ect... cannot be mapped exactly.

So your lut can be mapped to a cg render, but not cover the entire dynamic range of cg render.
Your lut cover only 2^15, minimum raw cg render (16bit) is twice the level value. So like a say before, black or white value (in some cases) will be clipped.
Data level distribution, won't match either.

Anyways, nobody care about mapping lut.
Title: Re: dubcats secret little hideout
Post by: Juraj Talcik on 2017-04-05, 22:36:33
Anyways, nobody care about mapping lut.

I don't see what is the issue ?

It's free post-production tool, no one is holding gun against head of anyone. Do you provide some better one ?
Title: Re: dubcats secret little hideout
Post by: Hamburger on 2017-04-06, 01:09:21
Hey dubcat, is there a way to apply your luts in photoshop?

You can apply it through the Color Lookup layer. It works really well if you make it 50%. It gives a super nice contrast to exterior and interior renders I've tested to.
Title: Re: dubcats secret little hideout
Post by: romullus on 2017-04-06, 10:22:35
Hey dubcat, is there a way to apply your luts in photoshop?

You can apply it through the Color Lookup layer. It works really well if you make it 50%. It gives a super nice contrast to exterior and interior renders I've tested to.

I tried to load it through colour lookup adjustment layer and i get very different result than in Corona's VFB.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2017-04-06, 16:55:50
Hey dubcat, is there a way to apply your luts in photoshop?

If you're render is in in 32 bit, Photoshop will apply the LUT in linear.
Photoshop will also clip your render, so you are better off applying it in the new Corona app.
Title: Re: dubcats secret little hideout
Post by: Marcus on 2017-04-06, 17:26:47
Hey dubcat.

Thanks for your work on these LUTs and thanks for sharing it!
I really appreciate you effort on research and sharing everything to the community.

Here is a quick test with ...01.cube
I just applied the lut in Corona Frame Buffer. Nothing more.
I like it and will experiment further with it.

Best,
Marcus
Title: Re: dubcats secret little hideout
Post by: romullus on 2017-04-06, 19:15:00
If you're render is in in 32 bit, Photoshop will apply the LUT in linear.
Photoshop will also clip your render, so you are better off applying it in the new Corona app.

Yes, my render is 32 bit cessential render elements blended with linear dodge blend mode and on top of that is added colour lookup adjustment layer with your lut in normal blending mode, but result is very different than i get when apply the same lut in CVFB. Maybe i should have to change colour lookup layer's blending mode to linear dodge too?
Title: Re: dubcats secret little hideout
Post by: dubcat on 2017-04-06, 19:36:30
LUTs behave as sRGB in Corona, and Photoshop 32bit behave as linear.

Nice Marcus :)
Title: Re: dubcats secret little hideout
Post by: romullus on 2017-04-06, 20:13:48
Oh, i see, so there's no way to get exact match between those two?
Title: Re: dubcats secret little hideout
Post by: miaz3 on 2017-04-06, 20:51:18
Anyways, nobody care about mapping lut.

I don't see what is the issue ?

It's free post-production tool, no one is holding gun against head of anyone. Do you provide some better one ?
I just provide additional information that would allow for better control.
To see where problems may arise, you can read my previous post.




Title: Re: dubcats secret little hideout
Post by: JakubCech on 2017-04-07, 09:52:19
Angle Affect
This feature should be included in Corona if you ask me! I notice this effect each time I lay down, even on rough fabrics.
Next time you lie down in bed or drunk on the floor, try to look for this effect, and then go and +1 mantis (https://corona-renderer.com/bugs)!
(http://i.imgur.com/TsfxREx.png)
(http://i.imgur.com/bfKVUHm.png)

This is a very important request. Almost all materials I do I input falloff to the ref glossiness map to mimic this behaviour. I think this could be default behaviour - I think 90% of materials work this way (visually). So +1 from me.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2017-04-12, 23:49:01
Oh, i see, so there's no way to get exact match between those two?

Totally forgot to reply, been busy with deadlines. I added a Linear version to the original post last Thursday, don't know if you noticed.
But remember that Photoshop will clip anything above 255 even if you are in 32bit, if you plan on doing adjustments after the LUT, you are better off applying it in Corona/Corona Image App.

edit:
Big thanks to JakubCech for the +1 :)
Title: Re: dubcats secret little hideout
Post by: romullus on 2017-04-13, 10:00:45
I added a Linear version to the original post last Thursday, don't know if you noticed.

No, i didn't. Thanks for pointing that out, i will give it a test as soon as i will get a chance to do so. And big thanks for your effort in general!!!
Title: Re: dubcats secret little hideout
Post by: Fluss on 2017-05-03, 19:36:27
Angle Affect
This feature should be included in Corona if you ask me! I notice this effect each time I lay down, even on rough fabrics.
Next time you lie down in bed or drunk on the floor, try to look for this effect, and then go and +1 mantis (https://corona-renderer.com/bugs)!
(http://i.imgur.com/TsfxREx.png)
(http://i.imgur.com/bfKVUHm.png)

This is a very important request. Almost all materials I do I input falloff to the ref glossiness map to mimic this behaviour. I think this could be default behaviour - I think 90% of materials work this way (visually). So +1 from me.

Well, Ondra almost promised it a long time ago. "AFAIK this is part of disney BRDF model, so it will be almost certainly included in Corona PBR mtl" -> https://corona-renderer.com/forum/index.php?topic=12621.0
Title: Re: dubcats secret little hideout
Post by: worx on 2017-05-06, 06:45:10
Update:

I got it working and quite like the results

The 01b is the version with the luts and 210w 34b sRGB

Which lut was used for this? Also was it applied in max corona or in PS?
I have been trying to achieve the same gradient like fall off in corners for soo long now and i just cant. Default interiors just look so flat and i resort to blending AO in ps, but its just not the same.

Would you mind talking about how that was achieved? Any clues would be great!
Title: Re: dubcats secret little hideout
Post by: dubcat on 2017-09-30, 03:04:48
(https://i.imgur.com/u22xzYU.png)

These radius settings are at 1k, multiply K by whatever you are using.
Title: Re: dubcats secret little hideout
Post by: PROH on 2017-09-30, 19:28:49
Hi dubcat. I am trying to rebuild some old corona materials with the new BPR settings, and wanted to use your IOR excel shead, but I cant get permission to download it. So would it be possible to get you to make a new/different link to this (for example Dropbox)?

Best regards.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2017-10-02, 21:44:24
wanted to use your IOR excel shead

Hey!
Some folders on my google drive got messed up, I need to dig through the backup log and make new links.

--------------------------------------------------------------

I finally got around to make a real time high pass filter + albedo changer.
I've been using this technique for years in Photoshop, but now I can adjust everything live in IR!

(https://i.imgur.com/5jU5HRu.jpg)
Title: Re: dubcats secret little hideout
Post by: snakebox on 2017-10-03, 03:08:44
(https://i.imgur.com/u22xzYU.png)

These radius settings are at 1k, multiply K by whatever you are using.

How on earth did you come up with these numbers?  just feels good or is there some science to it? (like most of the stuff you do :) )  interesting approach for sure, keep it up!
Title: Re: dubcats secret little hideout
Post by: dubcat on 2017-10-03, 08:07:24
How on earth did you come up with these numbers?
They try to emulate the typical setting that Scandinavian interior photographers use in Lightroom. Lightroom still looks better, but it's nice to have a little preview in VFB while working.

-----------------------------------------------------------

I''v uploaded a new spreadsheet.
It has two tabs "Reflectivity and IOR" and "Size to Real World Size"
I added Unreal 4 conversion to the sheet earlier this year.

(https://i.imgur.com/j0U3wvM.png)

https://docs.google.com/spreadsheets/d/1jdENLgrX7r85zhumLMpzreNf11tmFuBhv3UXiEMgG1E/
Title: Re: dubcats secret little hideout
Post by: PROH on 2017-10-03, 12:56:50
Thank you so much :)
Title: Re: dubcats secret little hideout
Post by: johnymrazko on 2017-10-03, 13:34:20
(https://i.imgur.com/u22xzYU.png)

These radius settings are at 1k, multiply K by whatever you are using.

should only blur and sharpen radius be multiplied by k? or amount as well?
Title: Re: dubcats secret little hideout
Post by: dubcat on 2017-10-03, 14:43:36
should only blur and sharpen radius be multiplied by k? or amount as well?

Only radius.
It's hard to tell if the radius parameters scale linearly, since we can't just scale the renders down and compare.
Sharpen in Corona is really harsh, even 0.001 sharpen radius crush blacks.

-----------------------------------

For people who tried to make a copy of the spreadsheet when I first uploaded it, try again now. The function was disabled for whatever reason.
Title: Re: dubcats secret little hideout
Post by: johnymrazko on 2017-10-03, 19:58:56
Thank you,

do you also know what would be the equivalent values in Lightroom?
Title: Re: dubcats secret little hideout
Post by: dubcat on 2017-10-03, 20:41:04
These are the average values

(https://i.imgur.com/bJWSTub.png)
Title: Re: dubcats secret little hideout
Post by: Fluss on 2017-10-06, 10:54:18
I find it strange to use LUT that is not related to the digital depth of the image rendered ?!
Maybe I'll release 64 sliced versions in the future, 41+ should be enough for what you want.

What cameras are used for the extracted LUT ?
I went into my Canon/Nikon folders and selected 3 random LUTs. I got a lot of Canon 60D LUTs in there, so one of them might be 60D.

Canon cameras have this magenta Tint to them, sometimes -10 green. This happens even if you calibrate the camera as perfect as you can. We need to use the sexy Tint feature in CameraRAW to get a perfect white balance. Since I'm dumping the real deal, I left this error in there. If you notice a slight magenta shift, it's a Canon LUT 99%.

Canons best friend.

(http://i.imgur.com/VADHSTy.png)

and a big thanks to everyone else that has responded!

If you are a canon user, you should try magiclantern. It's a custom firmware that extends camera capabilities. There is a withe balance function that can actually correct the magenta shift.

Edit: http://www.magiclantern.fm/
Title: Re: dubcats secret little hideout
Post by: lmikkelb on 2017-10-06, 23:18:38
Just one question, to clarify. We are viewing srgb and applying luts thats based on srgb right? good job with the luts and everything by the way, that corona mask thing looks amazing.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2017-10-10, 13:05:05
srgb right?

Yes, viewed as sRGB :)
Title: Re: dubcats secret little hideout
Post by: dubcat on 2017-10-31, 16:38:57
Every now and then I get Megascans questions. I'm posting this here, so I can link to this post.

-== HDRi Setup ==-

Megascans use a HDRi named "Pisa courtyard nearing sunset, Italy" as default
You can get this HDRi for free here http://gl.ict.usc.edu/Data/HighResProbes/

If you want to mimic the Megascans preview images, set "U Offset" to -0.57
Remember to set "U Tiling" to -1, since 3dsmax project from the outside and flip our HDRi.

(https://i.imgur.com/pKi43wD.png)

-== Mesh Setup ==-

Create a 2x2m Plane and tile it like this

(https://i.imgur.com/sHrn2xX.jpg)

-== Material Setup ==-


In this example I will use "Soil_Mud_pjuph20"

After you have extracted the .zip file with Bridge, you can double click the preview image and it will take you to the material folder.

Open Albedo and AO in Photoshop. Copy the AO map above Albedo and change the blending mode to "Multiply". Save it as AlbedoAO.

(https://i.imgur.com/nfWYQR5.png)

Megascans is made for PBR engines that use Specular.

0 Specular = 1 IOR
0.5 Specular = 1.5 IOR
1 Specular = 1.79 IOR

Since Corona is based on IOR, we have to convert the Specular map to IOR.
I've made a "Specular to IOR" LUT that gets shipped with Bridge, but it's kinda hidden.
You can find it here "C:\Program Files\Quixel\Megascans Bridge\Bridge_Data\Support\SpecularToIOR.CUBE"

Open the Specular map in Photoshop
Change the mode to 16bit
Add a "Color Lookup" layer and select "SpecularToIOR.CUBE"
Hit CTRL + Shift + E to flatten the layer stack
Change the mode back to 8bit and save it as IOR.

(https://i.imgur.com/3pHsOZc.png)
(https://i.imgur.com/UabI4fK.png)

Inisde the material folder there is a ".json" file. Open this file in Notepad++ or whatever you use.
Search for "Height"
In this example the Height value is "0.042 m", convert this value to cm.
Our displacement height should be 4.2cm.

(https://i.imgur.com/snqhYJJ.png)

Load the maps like this.
"Flip Green" inside CoronaNormal.

(https://i.imgur.com/tz5Qph5.png)

Depending on how you want the displacement to behave, you can use Min 0 Max 4.2. Or Min -2.1 Max 2.1

(https://i.imgur.com/YmEvPBd.png)

-== Camera Setup ==-

If you want to mimic Megascans, you can place your camera like this.
24mm Focal Length.

(https://i.imgur.com/1TKrv9u.jpg)

-== Render Setup ==-

Set size to 1450x816.
Set "Secondary solver" to "Path  Tracing"
Reduce "Screen size (px)" until your pc start to smoke, then dial it back a little.

(https://i.imgur.com/qeCCBut.png)

-== VFB Setup ==-

Set EV to 2.61 if you are using the same HDRi as me.
Megascans love their Vignette, so set it to 0.8
They also love to overdrive Sharpen, so set it to 10 !!!

(https://i.imgur.com/UyYefwT.png)

-== Test Render ==-

Beauty

(https://i.imgur.com/p2sQFXU.jpg)

Direct

(https://i.imgur.com/vajm91Z.jpg)

Reflection

(https://i.imgur.com/ErPh2hV.jpg)

Displacement

(https://i.imgur.com/YDtnW0G.jpg)

Displacement + Normal

(https://i.imgur.com/2oKAR6g.jpg)
Title: Re: dubcats secret little hideout
Post by: romullus on 2017-10-31, 18:49:54
That's very interesting. I always thought that specular map is optional to plug into reflectivity slot, just to make occluded areas less shiny. I wonder how much of a difference it makes when converted in to IOR and plugged in to according slot?

By the way, is there some other way to convert specular to IOR, for those who doesn't have megascan bridge?
Title: Re: dubcats secret little hideout
Post by: hkezer on 2017-10-31, 19:04:51
Hey dubcat, I want to ask you a kind of technical question, which I cannot figure out exactly.

I have been using your LUTs almost like always :) then I wanted to try, https://masteringcgi.com.au/product/3d-collective-professional-filmic-luts/ this ones from Adan.

And there were 2 folders, sRGB and Linear. And they say, I should use sRGB in corona VFB, and in photoshop and vray I should use Linear. but I have no idea why. Can you a little explain the reason and how can I get the most out of it?
Title: Re: dubcats secret little hideout
Post by: dubcat on 2017-10-31, 20:19:05
Hey guys!

is there some other way to convert specular to IOR, for those who doesn't have megascan bridge?

I'm attaching my old LUT that is shipped with Bridge, and a new version that I generated a few weeks back.
The new version was generated with code and can remap any value. The old version was made manually and can go to IOR 8 or something like that. Photoshop 2018 doesn't like 3dl though.

This is without the IOR map

Beauty

(https://i.imgur.com/JGarrQj.jpg)

Reflection, eeeeeww nasty.

(https://i.imgur.com/lSZPVkl.jpg)

Can you a little explain the reason and how can I get the most out of it?

A LUT looks at specific locations and then remap the RGB value to a new value. sRGB has a gamma curve, so you have to use LUTs that are made for that gamma.

Corona use sRGB
Photoshop use sRGB for 8/16bit and Linear for 32bit.

Here is a quick demonstration, so you can see the difference. Both use the same sRGB LUT 100%.

(https://i.imgur.com/A9OIsAB.jpg)

If you only have sRGB LUTs, but want to use them on a linear image, you can use this dirty little hack.
If I had done this to the Linear example above, it would look identical to the sRGB example.

(https://i.imgur.com/RHciaal.png)
Title: Re: dubcats secret little hideout
Post by: PROH on 2017-10-31, 22:27:23
Hi Dubcat. Is there anyway to convert secular to IOR inside Max/Corona? I tried using a Corona output map with your LUT (cube), and got something decent, but not quite right. Can this be done somehow?
Title: Re: dubcats secret little hideout
Post by: romullus on 2017-10-31, 22:32:45
Thank you very much! Do you know, how they come up with that specular/IOR map? Everyone is telling that PBR workflow is ~1,5 IOR for dielectrics and reflection all the way to the max, but from your examples it's pretty obvious, that some variance in IOR, does wonders to final result.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2017-10-31, 23:00:30
Hey

and got something decent, but not quite right

This!
I actually asked Ondra a week or two ago if there was a bug inside CoronaOutput. Because the result is always off by a few RGB, and these IOR values are super sensitive.
I have tried to load the bitmap as 1.0/2.2, convert in and out of gamma. The values are always a little off.

Do you know, how they come up with that specular/IOR map?

Open one of the specular maps inside Photoshop as 32bit, sample the values

(https://i.imgur.com/gPLTr1A.png)

In this case it is 0.0358

0.0358 * 100 = 3.58% Reflectivity
(1+SQRT(0.0358))/(1-SQRT(0.0358)) = 1.47 IOR

No idea how they scan it.
Title: Re: dubcats secret little hideout
Post by: PROH on 2017-11-01, 00:02:33
Thank you :) So far my best converting result inside Max/Corona is this:

- Load Gloss map with gamma 2.2, and put this into a Corona Output Map
- Set "Affected by tonemapping" ON
- Load "Specular to IOR.cube" LUT, with opacity 1
- Set gamma to 0,5 (this value is purely by eyeballing)

Will do some more testing later...
Title: Re: dubcats secret little hideout
Post by: dubcat on 2017-11-02, 16:31:46
This setup generates proper IOR maps
Enable "Affected by VFB"

(https://i.imgur.com/o6vejQU.png)
Title: Re: dubcats secret little hideout
Post by: PROH on 2017-11-02, 22:03:06
Thank you so much. I see now that I wrote "gloss map" instead of "specular map" in my previous post :(

I've tried your setup, and if EXposure is anything else than 0 (with a calibrated HDR) then I only get a good/realistic result when "Affected by VFB" is activated. Probably need to test a bit more...

Thanks for sharing your knowledge:)
Title: Re: dubcats secret little hideout
Post by: dubcat on 2017-11-02, 23:59:52
I've tried your setup, and if EXposure is anything else than 0 (with a calibrated HDR) then I only get a good/realistic result when "Affected by VFB" is activated.

Thanks. I only tested on EV 0.
Updated my last post.

edit:
We really need to get this sorted, there is no reason why EV should impact a material map :|
Title: Re: dubcats secret little hideout
Post by: Jpjapers on 2017-11-03, 10:00:12
(https://i.imgur.com/u22xzYU.png)

These radius settings are at 1k, multiply K by whatever you are using.

This is cool.
Just so im understanding correctly then, how would you calculate the settings for a 4k image? Youd just multiply those numbers by 4?
Or am i misunderstanding completely?
Show your working please :D
Title: Re: dubcats secret little hideout
Post by: dubcat on 2017-11-17, 03:58:39
just multiply those numbers by 4?

I don't know if the values scale linearly with render size, we need someone from the dev team to answer this. I just use the settings as a place holder in IR, and then do the real sharpening in Lightroom.

-----------------------

-5.65 EV is the value for default peak sun / corona sky. If you guys want to calibrate your HDRis.

-----------------------

edit:

Sharpen amount 10 / sharpen radius 1.0 seem to be consistent with Lightroom 150.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2017-11-24, 23:43:43
I was tired of the default material sphere that stretch materials all over the place. Here is a little guide on how to make a good looking material sphere.

Create a GeoSphere 50cm radius, since most scans nowadays are 1 meter.
128+ segments.
Type "Octa"

(https://i.imgur.com/DSHiuZ4.png)

Throw a "Spherify" on there just to be safe

(https://i.imgur.com/xCxtHAI.png)

Add a "UVW Map" "Planer" mode

(https://i.imgur.com/JR57ok8.png)

Default Sphere, nasty

(https://i.imgur.com/S7bjiDF.png) (https://i.imgur.com/wqMEWj8.png)

Box turned in to a sphere

(https://i.imgur.com/hDxnzfe.png)

GeoSphere with Planar

(https://i.imgur.com/W9XwCyk.png) (https://i.imgur.com/SKcK10w.png)
Title: Re: dubcats secret little hideout
Post by: dj_buckley on 2017-11-25, 19:48:11
Jeez this thread is difficult to follow - to many subjects being discussed and replies to question multiple posts up without quoting the original question.  My head is gonna explode.  It's like opening a WhatsApp group after not following it for a year haha.  Sounds like good stuff though
Title: Re: dubcats secret little hideout
Post by: vicmds on 2017-11-29, 04:33:01
Every now and then I get Megascans questions. I'm posting this here, so I can link to this post.

Thanks for sharing. Curious to know what your process to mimic them would look like for their (excellent) 3d plants, since their previews are apparently all UE4. Same material setup?
Title: Re: dubcats secret little hideout
Post by: dubcat on 2017-12-01, 16:30:34
Same material setup?

3D models ship with baked albedo+ao texture maps, so you can skip the merging part.
For Translucency Fraction I usually use a value from 0.3-0.4.
Sometimes the translucency maps work out of the box. Sometimes you have to boost the gain/reduce saturation/change the hue to taste.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2017-12-08, 01:21:04
(http://i.imgur.com/euMG6yq.jpg)

I noticed that I didn't specify the blending modes. The first height map blend is "Lighten", and the second blend is the lighten mix "Subtracted" from the top layer.
Title: Re: dubcats secret little hideout
Post by: romullus on 2017-12-08, 09:51:04
Didn't notice if mentioned before, but does blending has to be performed in linear or in sRGB space?
Title: Re: dubcats secret little hideout
Post by: dubcat on 2017-12-14, 20:40:07
sRGB space?
I need to find the max file to be 100% sure, but I think they all were linear.

----------------------------------------------------------------------------------------

I've remade the ACES Tonemapper with default settings in Photoshop.
The only thing you have to do, is to open your 32bit .hdr/.exr files in Photoshop and run the action.

Remember to leave "Highlight Compression" at 1 in Corona.

Raw

(https://i.imgur.com/TFYzv1K.jpg)

Photoshop Voodoo

(https://i.imgur.com/PxdCQWF.png)

ACES Tonemapped

(https://i.imgur.com/ytxfBb9.jpg)
Title: Re: dubcats secret little hideout
Post by: bluebox on 2017-12-16, 21:15:43
Can this be baked into LUT file for use inside Corona ?
Title: Re: dubcats secret little hideout
Post by: romullus on 2017-12-16, 23:38:30
Can this be baked into LUT file for use inside Corona ?
+1
Title: Re: dubcats secret little hideout
Post by: dubcat on 2017-12-18, 22:09:45
Can this be baked into LUT file for use inside Corona ?

I'll post the log LUT when the Corona log LUT loader gets fixed.

This is how it should work

Linear Render

(https://i.imgur.com/9jL9ZCW.png)

Linear converted to Cineon log, same as Corona.

(https://i.imgur.com/CX4romA.png)

Apply tonemapper LUT

(https://i.imgur.com/vVzZ0Sq.png)

Convert back to linear

(https://i.imgur.com/O6JVkob.png)

View as sRGB

(https://i.imgur.com/SKJ8oHb.png)

But this is what we get in Corona right now, using the same tonemapper LUT as above.

(https://i.imgur.com/gcV5yom.png)
Title: Re: dubcats secret little hideout
Post by: agentdark45 on 2017-12-19, 02:09:07
Can this be baked into LUT file for use inside Corona ?

I'll post the log LUT when the Corona log LUT loader gets fixed.[/img]

Devs can we get this done in a daily build? (says the guy that has zero idea how hard this is to implement).
Title: Re: dubcats secret little hideout
Post by: bluebox on 2017-12-19, 07:45:24
Can this be baked into LUT file for use inside Corona ?

I'll post the log LUT when the Corona log LUT loader gets fixed.[/img]

Devs can we get this done in a daily build? (says the guy that has zero idea how hard this is to implement).

+1 Yes please!

Or can someone who knows what to request make a feature request :D ?

BTW, thank you Dubcat for all your research !
Title: Re: dubcats secret little hideout
Post by: maru on 2017-12-19, 09:41:19
I'll post the log LUT when the Corona log LUT loader gets fixed.
Is this blackmailing? :D

Now seriously, is this officially logged somewhere outside of this forum thread, or discussed directly with Ondra?
Title: Re: dubcats secret little hideout
Post by: dubcat on 2017-12-19, 17:10:13
Is this blackmailing? :D

Hehehe, just want to be sure I'm sharing something that is actually working ;)

Now seriously, is this officially logged somewhere outside of this forum thread, or discussed directly with Ondra?

The devs know about it, but I've made a new mantis report.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2017-12-21, 03:10:27
I'm compiling a tonemapper pack for you guys.
The funny thing is that all the top tonemappers out there kinda look the same on the curve, but they look so different on the final render.

Here is a little teaser.

Secret Render Engine

(https://i.imgur.com/9nJooKX.png)

ACES

(https://i.imgur.com/6WOQl7s.png)

Camera RAW 2012 (The one I've been using for years, for compression).

(https://i.imgur.com/a4A3NTv.png)
Title: Re: dubcats secret little hideout
Post by: nkilar on 2017-12-21, 12:57:08
What I can I say dubcat, can't wait to see what you got cooking. It is much appreciated, Sir! :)
Title: Re: dubcats secret little hideout
Post by: bluebox on 2017-12-29, 08:23:29
Hey there Dubcat, how's work on those luts :D ? Can't wait to try them out. Thanks man !
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-01-11, 22:36:26
Hey there Dubcat, how's work on those luts :D ? Can't wait to try them out. Thanks man !

Hey!

The LUTs have been ready since December, just waiting for the devs to fix the loglut loader :)

edit:

These LUTs will compress and adjust contrast. Tonemappers like ACES also change how light intensity behaves, to do this we have to change color matrix.

Here is an example made by Koola, from the Unreal 4 community.

(https://i.imgur.com/zSj6y79.jpg)

ACES does a pretty good job at emulating how light intensity behaves, but it still has a bug with blue light. Blue turns into pink instead of cyan. fStorm has a custom matrix that correct this problem. Currently Corona does not change how light intensity behaves, so pure Red/Green/Blue will still be pure Red/Green/Blue. Stuff will look like "UE4 - Exp 0" no matter what you do.
Title: Re: dubcats secret little hideout
Post by: serch on 2018-01-13, 00:26:08
The LUTs have been ready since December, just waiting for the devs to fix the loglut loader :)
u do.

Are devs actually working on the fix?
Title: Re: dubcats secret little hideout
Post by: oddvisionary on 2018-01-13, 07:55:55
Instead of fixing LUT it would be better if they simply add support for OCIO. I can't trust LUT for this kind of stuff. I prefer having a trusted color management system like OCIO (works like a charm in Arnold C4D, no LUT).

LUT should just be used for pre-viz grading.
Title: Re: dubcats secret little hideout
Post by: bluebox on 2018-01-13, 15:03:10
Thanks Dubcat :), asked if Devs are working on this topic in the daily builds topic. We'll see how it goes.

As for using LUTs only for previz grading - if something works out of the box then why overcomplicate it ;) ?
Title: Re: dubcats secret little hideout
Post by: Juraj Talcik on 2018-01-13, 15:48:43
Instead of fixing LUT it would be better if they simply add support for OCIO. I can't trust LUT for this kind of stuff. I prefer having a trusted color management system like OCIO (works like a charm in Arnold C4D, no LUT).

LUT should just be used for pre-viz grading.

Dubcat and everyone is well aware of this, but adding full color-management has been requested for more than two years. It just doesn't feel like it will happen anytime soon, so any hack in mean-time would still be very welcome addition. Yes, LUT has certain primary use, but that doesn't mean it can't be used outside of the box for anything else.
Heck, even the main tech luminaries behind game dev like John Hable suggested LUT to be ok solution for tonemapping.

Title: Re: dubcats secret little hideout
Post by: oddvisionary on 2018-01-16, 09:34:25
Instead of fixing LUT it would be better if they simply add support for OCIO. I can't trust LUT for this kind of stuff. I prefer having a trusted color management system like OCIO (works like a charm in Arnold C4D, no LUT).

LUT should just be used for pre-viz grading.

Dubcat and everyone is well aware of this, but adding full color-management has been requested for more than two years. It just doesn't feel like it will happen anytime soon, so any hack in mean-time would still be very welcome addition. Yes, LUT has certain primary use, but that doesn't mean it can't be used outside of the box for anything else.
Heck, even the main tech luminaries behind game dev like John Hable suggested LUT to be ok solution for tonemapping.

For sure! I tried a lot of color management LUT tests. I stopped and instead focused on a post-workflow. I just export un-tonemapped renders (openEXR) and do the rest in Davinci Resolve/Fusion or After Effect which some of them have a full color management system built in.

I requested OCIO (like Arnold Color management) they didn't said anything yet : https://corona-renderer.com/forum/index.php?topic=18169.msg114140#msg114140

I use OCIO with Arnold, works very well! I can even edit and "write" my own LUT and configs and the ACES official forum is full of information about ACES in CGI. Hoping to get it to Corona as well soon or later (more later, I think Node graph is more a priority right now in C4D).
Title: Re: dubcats secret little hideout
Post by: Njen on 2018-01-16, 23:51:13
For sure! I tried a lot of color management LUT tests. I stopped and instead focused on a post-workflow. I just export un-tonemapped renders (openEXR) and do the rest in Davinci Resolve/Fusion or After Effect which some of them have a full color management system built in.

This is exactly my workflow as well, simple and uncomplicated to just render out linear exr's and then comp them together in Nuke, a program I 100% trust for colour management (with the right tools).
Title: Re: dubcats secret little hideout
Post by: oddvisionary on 2018-01-17, 00:17:02
For sure! I tried a lot of color management LUT tests. I stopped and instead focused on a post-workflow. I just export un-tonemapped renders (openEXR) and do the rest in Davinci Resolve/Fusion or After Effect which some of them have a full color management system built in.

This is exactly my workflow as well, simple and uncomplicated to just render out linear exr's and then comp them together in Nuke, a program I 100% trust for colour management (with the right tools).

LUT should be used like in real life, for movies etc. They have a camera (more than one obviously) they apply a custom lut made on set by an on set colorist, so they can a pre-color graded look of the shot (more immersive for the direction/DOP).

Same for CG, I use LUT just to check out how it would be with some post or mood. It can be handy to do everything in the frame buffer, but best solutions is always post.

Nuke is for sure a trusted software for that, and complete with OCIO/ACES/FILMIC.
Title: Re: dubcats secret little hideout
Post by: agentdark45 on 2018-01-17, 00:51:33
Hey there Dubcat, how's work on those luts :D ? Can't wait to try them out. Thanks man !

Hey!

The LUTs have been ready since December, just waiting for the devs to fix the loglut loader :)

edit:

These LUTs will compress and adjust contrast. Tonemappers like ACES also change how light intensity behaves, to do this we have to change color matrix.

Here is an example made by Koola, from the Unreal 4 community.

[img width=500 height=340]https://i.imgur.com/zSj6y79.jpg[img]

ACES does a pretty good job at emulating how light intensity behaves, but it still has a bug with blue light. Blue turns into pink instead of cyan. fStorm has a custom matrix that correct this problem. Currently Corona does not change how light intensity behaves, so pure Red/Green/Blue will still be pure Red/Green/Blue. Stuff will look like "UE4 - Exp 0" no matter what you do.

This is such a huge part of rendering I really don't know why we aren't looking into this with greater detail.

Please devs can we bump this up on the priority list?

How about a simple check box to unlock an "advanced tone mapper". That way all previous files render exactly the same, but for those that want to go further we have some more options (which doesn't clutter the UI by default).
Title: Re: dubcats secret little hideout
Post by: Juraj Talcik on 2018-01-17, 13:59:06

How about a simple check box to unlock an "advanced tone mapper". That way all previous files render exactly the same, but for those that want to go further we have some more options (which doesn't clutter the UI by default).

Yup, full (and correct this time) filmic this way would be great.

Maybe in 2020 :- )
Title: Re: dubcats secret little hideout
Post by: oddvisionary on 2018-01-17, 14:23:22
.
Title: Re: dubcats secret little hideout
Post by: Rhodesy on 2018-01-17, 17:20:16
Yes I think the C4D dev team is separate to the main Corona app. Also the tone mapping would quickly come to both as they use the same frame buffer window.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-01-19, 03:52:55
I want to state that all my posts are directed to still image architectural visualization. The stuff I post is not directed for people who use a "pipeline", like CGI film. I need to get quick and good results straight out of the frame buffer. I like to think of VFB as a photo, and then I can open the "photo" in Lightroom/CameraRaw and do the final tweaks if I want to. The logLUTs are a temporarily "hack" solution, until Corona can get a more advanced tonemapper with custom matrix. It's not a question if Corona should get a new tonemapper or not, but when. Currently I use my own custom scripts in Fusion, but I really don't want to. fStorms tonemapper is superior in every way right now. It has a shoulder, it has a toe. It adjust light intensity according to real photos. It has a custom matrix that takes care of the blue turns to pink problem. It might not be 100% photo correct, but it's not pink. I only use Corona, and it hurts to say this, but it's the truth. We are not on top of the food chain when it comes to tonemapping, and there is no reason why. Corona Team = Best Team.

edit: fixed some typos, damn you auto correct!
Title: Re: dubcats secret little hideout
Post by: agentdark45 on 2018-01-19, 16:15:17
I want to state that all my posts are directed to still image architectural visualization. The stuff I post is not directed for people who use a "pipeline", like CGI film. I need to get quick and good results straight out of the frame buffer. I like to think of VFB as a photo, and then I can open the "photo" in Lightroom/CameraRaw and do the final tweaks if I want to. The logLUTs are a temporarily "hack" solution, until Corona can get a more advanced tonemapper with custom matrix. It's not a question if Corona should get a new tonemapper or not, but when. Currently I use my own custom scripts in Fusion, but I really don't want to. fStorms tonemapper is superior in every way right now. It has a shoulder, it has a toe. It adjust light intensity according to real photos. It has a custom matrix that takes care of the blue turns to pink problem. It might not be 100% photo correct, but it's not pink. I only use Corona, and it hurts to say this, but it's the truth. We are not on top of the food chain when it comes to tonemapping, and there is no reason why. Corona Team = Best Team.

edit: fixed some typos, damn you auto correct!

All of the above x2

If you check the gallery, most guys on the forums are posting archviz stuff made using 3ds max. Only a small minority of Corona users are messing with Nuke e.t.c. I don't see why improving the tonemapping features of Corona to make it on par, or even surpassing the quality of F-Storm somehow detracts from the functionality for the compositing guys (it will still be there if you want it).

I'd bet my left arm that most people want an all in one solution that can produce the prettiest images out of the box, with the least amount of hassle.

This is also why I stick with Corona and don't go full into F-Storm, there are too many limitations with it despite it producing very photorealistic images.
Title: Re: dubcats secret little hideout
Post by: bluebox on 2018-01-19, 19:36:18
Exactly. If you want to go pro, you still can.

As we work closely with interior designers  there is also the aspect of the images being exactly the same throught many many preview turns.
I can't imagine editing say 30 shots each time with external software, caring to maintain contrast etc. at the same level. Therefore (at least for us) getting the most straight out of VFB is very important.
Title: Re: dubcats secret little hideout
Post by: zuliban on 2018-01-19, 22:29:12
I gave up along time ago in renders VFB i just use the lineal image as open exr and do the rest in nuke.
Still renders need small tech improvements like a correct DOF, cat eyes effect and obstruction  refraction, dof where you can see some small rainbow in some bokeh shapes and some hairs obstruction from grass in other shapes, a more correct material that preserves energy on bump and so on it.
It also would be nice to have this correct tone mapping that can mimics real world cameras and old school films.

And of course caustics... i feel nobody is looking at this anymore (corona roadmap have them)they really brings a image to life when it has enough glass or reflective surfaces.
I also have tested fstorm and i agree it feels like a real camera inside a render and create very realistic fast renders, but still i don't like the gpu low memory limitation make them really unusable for big textures or closeups maybe in some years we can have some nice 64gb cards and if miners are cool a good price range.

I also have seen some tech from Arion render and it has alot of nice features that other renders don't have like the dof obstruction and better materials i wonder why people don't use that render?
i tested it when it introduced bloom and glare before any other render then they deteached it to arionfx plugin.
Title: Re: dubcats secret little hideout
Post by: oddvisionary on 2018-01-22, 16:32:29
I gave up along time ago in renders VFB i just use the lineal image as open exr and do the rest in nuke.
Still renders need small tech improvements like a correct DOF, cat eyes effect and obstruction  refraction, dof where you can see some small rainbow in some bokeh shapes and some hairs obstruction from grass in other shapes, a more correct material that preserves energy on bump and so on it.
It also would be nice to have this correct tone mapping that can mimics real world cameras and old school films.

And of course caustics... i feel nobody is looking at this anymore (corona roadmap have them)they really brings a image to life when it has enough glass or reflective surfaces.
I also have tested fstorm and i agree it feels like a real camera inside a render and create very realistic fast renders, but still i don't like the gpu low memory limitation make them really unusable for big textures or closeups maybe in some years we can have some nice 64gb cards and if miners are cool a good price range.

I also have seen some tech from Arion render and it has alot of nice features that other renders don't have like the dof obstruction and better materials i wonder why people don't use that render?
i tested it when it introduced bloom and glare before any other render then they deteached it to arionfx plugin.

You should try Indigo Render for caustics. The best for now, and they use MTL (Metropolis Light Transport) algorithm calculation, that are not implemented to Corona, which is why Corona caustics are nice but not the best.

You can get better caustics when using experimental settings : Bidir/VCM (if I remember correctly, I only tried once to use it for tests).
Title: Re: dubcats secret little hideout
Post by: snakebox on 2018-01-23, 00:20:50
Quote
You should try Indigo Render for caustics. The best for now, and they use MTL (Metropolis Light Transport) algorithm calculation, that are not implemented to Corona, which is why Corona caustics are nice but not the best.

I don't mean to hijack the topic, but I was pleasantly surprised by Redshifts caustics.

small test to demonstrate:
https://vimeo.com/239298771 (https://vimeo.com/239298771)

It's still a post process like in vray I believe, but I found them much easier to use and also liked the result better. Caustics in Corona does not make sense to me, doesn't give me what I expect nor do I feel like I have any control. Hopefully that changes one day.
Title: Re: dubcats secret little hideout
Post by: romullus on 2018-01-23, 10:57:56
Caustics are on roadmap for V3: https://trello.com/b/EfPE4kPx/corona-road-map-3ds-max
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-01-26, 01:47:22
This is from an older post I made on the forum somewhere, but I want to consolidate all the important stuff in this thread.

This is how Corona behaves today.

(https://i.imgur.com/g4udgKx.png)

This is default fstorm.

(https://i.imgur.com/fpzjT6c.jpg)

These are fstorm with adjusted parameters.

(https://i.imgur.com/FxjsJaS.jpg)

fStorm at 0.99 is the same as current Corona

(https://i.imgur.com/G4AZzEx.jpg)

I just want to state again that I'm not trying to provoke, I don't like to make 1:1 comparisons between render engines. I'm posting all these findings because I think it will improve Corona as a render engine. Corona Team, you know I love you.

fStorm split the HDRi into indirect and direct pass, and I think this is the reason fStorm has different shadow values. I've talked to the Corona dev team, and they have ensured me that Corona use the correct method. So ignore the value difference, this post is about the diffuse roughness. I've made my own custom Corona to fstorm and fstorm to Corona converter, and when it comes to interior renders, diffuse roughness has a lot to say on the final render. This is a parameter that should not be overlooked by the dev team.
Title: Re: dubcats secret little hideout
Post by: Dionysios.TS on 2018-01-26, 01:54:00
+1
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-01-26, 15:24:48
Dubcat I don't understand what you're trying to demonstrate in your last post. Can you explain a little bit further pls?
Title: Re: dubcats secret little hideout
Post by: romullus on 2018-01-26, 15:43:34
Open images in new tabs and switch between them. Look at sphere's shadow terminator - the difference should be obvious.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-01-27, 17:22:25
Can you explain a little bit further pls?

As romullus said :)

--------------------------------------------------------------

I'm posting a little weekend present for you guys, these settings emulate the default ACES tonemapper with about 0.5 RGB error.
The settings might look ridiculous with negative "highlight compression", but trust me, give it a try ;)

(https://i.imgur.com/rUVXwo3.png)

I'm attaching a VFB settings file that you can load.
Remember to disable LUT if you are using one.

edit: I made these settings with "Corona 2018-01-25 Daily". I remember there were some filmic changes, but I can't remember if it was 1.6/1.7 or daily. Just letting you know in case stuff looks weird. The result should be pretty much identical to the ACES Photoshop script I posted earlier (https://corona-renderer.com/forum/index.php?topic=13398.msg116198#msg116198).
Title: Re: dubcats secret little hideout
Post by: agentdark45 on 2018-01-28, 15:42:46
I just tried out the above settings (with tweaked exposure) on some previous CXR's and I have to say I'm super impressed with the result!

Straight out of the VFB I'm getting some very pleasing images. Nice natural burnouts, good contrast/shadows and rich colours. We are definitely on to something here.

Comparison images below:

1. Default Corona settings with highlight compression at 8
2. Manually tweaked settings (no lut)
3. Manually tweaked settings (with lut)
4. Dubcat's settings
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-01-28, 21:31:23
Open images in new tabs and switch between them. Look at sphere's shadow terminator - the difference should be obvious.

Indeed, the transition between light and shadow is way softer in Fstorm. Much more pleasing to the eye.

How does the Vray alSurface shader does compare to this?

"The Fresnel effect is computed as part of the BRDF calculations (a.k.a. “glossy Fresnel”) and takes into account the viewing direction, the surface normal, and the light directions."

Isn't it related to this ?
nothing to do with the diffuse part, misread what you wrote

Also, As far as I remember, Corona shader does not support glossy fresnel.

(http://i.imgur.com/TsfxREx.png)
(http://i.imgur.com/bfKVUHm.png)

What's more, some users are experiencing strange atifacts with SSS here :

https://corona-renderer.com/forum/index.php?topic=18702.0

Which seems to be the exact same issue descibed here :

Quote
VRay Skin Mtl: This uses a two lobe specular model with a sharp and broad reflection. It also uses Phong as the reflective BRDF. This model proved to work well in many situations, but at glancing angles, based on the way that it would cut out the SSS, could cause darkening. This is because the Fresnel effect is computed as a function of the angle between the viewing direction and the surface normal, ignoring the directions from which lights illuminate the surfaces.

alSurface: This model also uses a two lobe specular model. However, instead of using a smooth BRDF like Phong or Blinn, it uses a microfacet one. The Fresnel effect is computed as part of the BRDF calculations (a.k.a. “glossy Fresnel”) and takes into account the viewing direction, the surface normal, and the light directions. The user has a choice between GGX and Beckmann BRDF models. Based on the nature of the micro faceting, it can avoid the darkening effect at the glancing angles through retro-reflection. Additionally it does not cover the SSS at the same glancing angles.

source : https://www.chaosgroup.com/blog/v-rays-implementation-of-the-anders-langlands-alsurface-shader

Of course, I might be totally misleading as i'm not a tech guru like some of you guys..

But there is one thing that bother me. We were experiencing some white halos on rough shaders some times ago. By looking at the examples here ( https://www.chaosgroup.com/blog/understanding-glossy-fresnel), it looks like a direct consequence of not supporting the glossy fresnel effect. It seems fixed now. But when i see that glossy fresnel isn't supported yet, i wonder if it has been fixed the correct way or with some workarounds (we have then seen some dark halos when the devs were trying to fix it, which strengthens me in my view that it wasn't done the right way).

Basically, initial implementation of the shader was good, it should be more reflective at grazing angles like it was doing BUT this effect should also be affected by the roughness as more micro-facets are facing the camera (so less grazing angles) on rough materials compared to shiny ones. If the whole thing is well implemented, angle affect should resolve by itself I guess.

fStorm split the HDRi into indirect and direct pass, and I think this is the reason fStorm has different shadow values.

That said, your statement totally make sense here.
Title: Re: dubcats secret little hideout
Post by: NicolasC on 2018-01-29, 09:16:51
Thanks A LOT Dubcat for all your investigations. Very instructive, a gold mine.
Hats off, really.
Title: Re: dubcats secret little hideout
Post by: Juraj Talcik on 2018-01-29, 17:05:05
Quote
it has been fixed the correct way or with some workarounds

It was some sort of workaround by manually fitting it to resemble the alsurface curve. And the diffuse part is still basic Lambert, which is responsible for the harsch look.

Ondra said he would like to look into this more now, not sure when that is but we should keep the pressure and push him towards it :- ).
Title: Re: dubcats secret little hideout
Post by: Dippndots on 2018-01-31, 00:53:07
Is your Megascans export script still available, Dubcat? The link in your Megascans thread 404s :(
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-01-31, 10:15:48
Quote
it has been fixed the correct way or with some workarounds

It was some sort of workaround by manually fitting it to resemble the alsurface curve. And the diffuse part is still basic Lambert, which is responsible for the harsch look.

Ondra said he would like to look into this more now, not sure when that is but we should keep the pressure and push him towards it :- ).

Hopefully, corona 2.0 will bring Vray compatibility and OSL support so we might be able to try that alshader inside corona sooner than later.
Title: Re: dubcats secret little hideout
Post by: Juraj Talcik on 2018-01-31, 10:29:55
OSL doesn't have access to BRDF though so I am not sure if we would get anything else than the values translated to CoronaMTL internally.
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-01-31, 11:25:22
OSL doesn't have access to BRDF though so I am not sure if we would get anything else than the values translated to CoronaMTL internally.

Just checked, you're right OSL does not allow to write custom BRDF / can only use what's available... That's sucks! So we have to wait for a proper 'state of the art' BSDF.

I was so optimistic ! Juraj you just ruined my day :)
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-02-01, 09:04:18
dubcat, can you share your scene pls ? I'd like to make some direct comparison with Vray alshader.


(https://i.imgur.com/g4udgKx.png)

Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-02-01, 16:43:24
We are definitely on to something here.

Glad you like it. :)

Thanks A LOT Dubcat

Thank you :)

Is your Megascans export script still available, Dubcat? The link in your Megascans thread 404s :(

I've been working on new scripts for Quixel since last winter.
The new scripts use my "Specular to IOR v2" LUT to auto convert specular maps, and they read the proper displacement height value from the json file.
I don't have a release date, but it will be worth the wait!

I'll make a new post here to inform you guys when it's released.

dubcat, can you share your scene pls ?

That scene is long gone, but I've made a new one for you. The zip contains a "Corona Sky" HDRi for consistent lighting and an fbx with geo/camera.
I had to use an external file sharing service, because the forum cap is at 30mb.

https://www.sharebase.net/58ed6f5e1e79212f (https://www.sharebase.net/58ed6f5e1e79212f)

(https://i.imgur.com/YhMd6eS.jpg)

Hope I didn't miss any questions, if so, let me know.

edit:
I forgot to mention that Epic has fixed the blue light problem in Unreal.

(https://i.imgur.com/sGbtYzk.jpg)(https://i.imgur.com/fTvIKKf.jpg)

edit edit:
Here is the ACES tonemapper if anyone is interested.

https://www.desmos.com/calculator/h8rbdpawxj (https://www.desmos.com/calculator/h8rbdpawxj)

If you look at the numbers on the left side of each column, these are the parameters.

4   - Slope        - 0.88
7   - Toe           - 0.55
8   - Black Clip  - 0
11 - Shoulder   - 0.26
12 - White Clip - 0.04
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-02-03, 12:45:55
Thanks dubcat for the scene. I'll make some comparison with shaders that support diffuse roughness
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-02-04, 12:58:56
I've finally made some test on the diffuse shading. Indeed, Corona seems to use pure Lambertian diffuse shading model which is suitable to describe high glossiness materials. When it comes to rougher materials, the oren-nayar model is more suitable.

example :

(http://images.slideplayer.com/26/8854613/slides/slide_35.jpg)

Arnold and redshift both use the oren-nayar diffuse shading model and then, expose a diffuse roughness parameter.

When diffuse roughness is set to 0, then it's pure Lambertian. As far as this value is changed, it switches to the Oren-Nayar implementation. You can see examples below (don't mind the little exposure difference between renderers, I matched them by eye, really quickly).

I did not find a Fstorm demo installation but from what I've seen from dubcat's tests, the Fstorm diffuse shading model seems quite off compared to other solutions. Don't know what algorithm is used there. Also noticed some strange artifacts on the sphere highlight in arnold when using strong roughness values. Redshift implementation seems to be the more consistent one.

Vray's diffuse roughness is completely off and I now understand why nobody (including me) uses it...

Also, to clarify things, diffuse roughness is not the same as glossy roughness. Most materials cap around 0.3 and shouldn't go over 0.5. From what I've found over the web, some artist tends to use a basic rule to get reliable results: diffuse roughness = glossy roughness * 0.33. There is something to dig in here.

It would be really nice to get diffuse roughness and glossy fresnel to be part of corona in the near future! Please!

Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-02-04, 15:07:39
one more test, Redshift , Lambertian vs Oren-Nayar diffuse shading :

Glossy roughness @0.7 - Diffuse Roughness @0.0

Glossy roughness @0.7 - Diffuse Roughness @0.23 -> 0.7*0.33 as explained above

Glossy roughness @1.0 - Diffuse Roughness @0.0

Glossy roughness @1.0 - Diffuse Roughness @0.33
Title: Re: dubcats secret little hideout
Post by: Juraj Talcik on 2018-02-05, 09:56:59
F-Storm does almost 100perc. use Oren-Nayar diffuse shading, or some in-house but nonetheless based on it (like their copy of GGX).

The most interesting approach is what the Disney guys (Brent) have done. They manually fitted the model so that rough materials have some retroreflection.

I generally like what they do (test and see when it matches reality) instead of just adding code and ending up with unrealistic crap. Lambert has to go.
Title: Re: dubcats secret little hideout
Post by: pokoy on 2018-02-05, 10:06:10
A few users were asking for Oren-Nayar on a regular basis, probably too few to be heard. It's really needed for a lot of surfaces, I'd be really happy if we got an improved shading model.

Thanks for the test images - from all the tests, Redshift's version looks best to me. Kind of surprising since I find many of their gallery images to look quite artificial, I always thought their shading model isn't as nice as Corona's.
Title: Re: dubcats secret little hideout
Post by: Juraj Talcik on 2018-02-05, 10:44:10
Redshift still suffers from this odd reputation because their early user-base didn't focus on photorealistic work that much.

But their 2nd version came with state-of-art PBR shader with multiple brdf selection in 1/10 fraction of the time it took Corona to even fix GGX halo ;- ).
It was basically flawless, perfection.
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-02-05, 11:42:33
The most interesting approach is what the Disney guys (Brent) have done. They manually fitted the model so that rough materials have some retroreflection.

I generally like what they do (test and see when it matches reality) instead of just adding code and ending up with unrealistic crap. Lambert has to go.

I've also read the disney paper, the approach is indeed quite interesting. The only thing that bother me in this shader is the specular control which stands in lieu of an explicit index-of-refraction. Except that, it looks like a fantastic shader to work with. Renderman is Full-featured and free for non-commercial use, just need to grab a demo version of maya to test that out.

I finally managed to test Fstorm and I have to say that I'm quite impressed! Everything feels so natural, and not only on the diffuse part, glossy fresnel is a no brainer here! I'll dig into it a bit further.

F-Storm does almost 100perc. use Oren-Nayar diffuse shading

I'm not sure about that. It's default 0.8 and seems to be "Lambertian-like" at 0.99. It's also capped to 0.5. What's more, transition between light and shadows is tremendously softer.


A few users were asking for Oren-Nayar on a regular basis, probably too few to be heard. It's really needed for a lot of surfaces, I'd be really happy if we got an improved shading model.

Thanks for the test images - from all the tests, Redshift's version looks best to me. Kind of surprising since I find many of their gallery images to look quite artificial, I always thought their shading model isn't as nice as Corona's.

A better diffuse model is highly needed to get rid of that rough surface plastic look.

After some more tests, I'm a bit skeptical about redshift's implementation as it's quite noticeable in the highlighted parts but it does almost nothing in the shadows. Arnold looks weird on extreme values but it also significantly changes the diffuse appearance in the shadows which looks more convincing to my eye. It's more noticeable on the happy Buddha, I'll post some more experiments later.
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-02-05, 14:04:11
Juraj, can you PM me ? I'd like to discuss some stuff with you if you don't mind
Title: Re: dubcats secret little hideout
Post by: nkilar on 2018-02-05, 15:24:56
Juraj, can you PM me ? I'd like to discuss some stuff with you if you don't mind

I'm a lurker here (without much to say) and I really appreciate you guys going at it - going at the problem that is. :) That said, the more public spamming you guys do the better - I really enjoy reading the findings you smart people come up with. Hurrah! Thank you!
Title: Re: dubcats secret little hideout
Post by: oddvisionary on 2018-02-05, 23:47:08
Juraj Talcik : F-storm + their? No, it's just one guy haha.
Title: Re: dubcats secret little hideout
Post by: Juraj Talcik on 2018-02-06, 10:39:23
Yeah I also prefer to bounce opinions public :- ). That's what threads like this are for. Don't worry the devs are not that sensitive and need some push :- )

But if it's something reeally private like just use my old mail juraj(dot)talcik (at) yahoo (com).
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-02-06, 13:08:34
Juraj, can you PM me ? I'd like to discuss some stuff with you if you don't mind

I'm a lurker here (without much to say) and I really appreciate you guys going at it - going at the problem that is. :) That said, the more public spamming you guys do the better - I really enjoy reading the findings you smart people come up with. Hurrah! Thank you!

Don't worry, will still sharing stuff here, just wanted to ask some hints to go further on the specular part without polluting the thread too much with trial and errors. Anyway, we're talking diffuse roughness, for now, let's see that later..

Here is another test to demonstrate the diffuse roughness contribution in Arnold. Diffuse shading is way smoother, diming light at F(0°) (which give the plastic look) and eliminating the black fringe Lambert tends to produce at grazing angles. Also, note that the whole thing appears to be darker, both tests were rendered in the same lighting and exposure condition. The shader is supposed to be energy conservative tho, that's just that diffuse rays are more scattered resulting in fewer rays hitting the camera hence darker render I guess.

edit: also grabbed a copy of the latest blender version which provides an implementation of the Disney uber shader. Will be interesting to see what it brings to the table :)
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-02-08, 15:45:00
Hey guys, I've made some more tests across different renderers to compare diffuse roughness at min/max values. Diffuse only, no specularity involved, here is what we get :

(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=79188;image)

(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=79190;image)

(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=79192;image)

(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=79194;image)

(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=79196;image)

We can see that Fstorm and PxrDisney really stand out here, simply by the fact that they are modifying the shadow terminator according to the roughness (diffuse roughness for Fstorm, global roughness for PxrDisney). We can also notice that PxrDisney shader brighten up the diffuse at grazing angles, which Fstorm doesn't. Let's try to go a little bit more in depth.

It looks like there are two models that seem to be involved here :
_the diffuse model
_the geometric shadowing-masking model

For the diffuse model, PxrDisney uses a custom-made empirical brdf based on their observation of MERL100 samples.

Quote
This produces a diffuse Fresnel shadow that reduces the incident diffuse reflectance by 0.5 at grazing angles for smooth surfaces and increases the response by up to 2.5 for rough surfaces. This seems to provide a reasonable match to the MERL data and was also found to be artistically pleasing.

This is clearly noticeable on the PxrDisney test. As a contrary, Fstorm doesn't seems to do such computation and I now assume Lambertian model is used there.

The shadow terminator seems to be driven by the geometric shadowing-masking model which represent the shadowing from the microfacets (a.k.a specular G function). The BRDF viewer allows us to preview the different BRDFs independently, to better see the distinct contribution of each function in the shader. I used it to preview some specular G functions and made some screen of the Walter BRDF which is the one that seems to be the closest to what we get in Fstorm.

Min and max :

(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=79198;image)

(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=79200;image)

This function exposes an alphaG parameter which has a range of [0.001;1]. What's more, the PxrDisney has been implemented as follow :

Quote
we use the G derived for GGX by Walter but remap the roughness to reduce the extreme gain for shiny surfaces. Specifically, we linearly scale the original roughness from the [0, 1] range to a reduced range, [0.5, 1], for the purposes of computing G.

This correlates very well with what we get in Fstorm -> diffuse roughness range [0.5;0.99].

However, the implementation of this function seems to differ blithely between the Fstorm shader and Disney shader. In the Disney shader, everything is derived from the global roughness setting and is automatically performed backend. In Fstorm, the parameter is exposed and this seems to affect the diffuse component only.

In regards to the "more directional look" Juraj and Dubcat were talking about, I've also made some test on the specular part :

Corona :

(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=79202;image)

Fstorm :

(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=79204;image)

I guess it's because Fstorm uses Beckmann BRDF instead of GGX :

Beckman :

(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=79206;image)

(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=79208;image)

GGX :

(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=79210;image)

(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=79212;image)
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-02-08, 16:55:25
Oh and just for the sake of it, here is a real photograph. Better than thousand words....

(https://nofilmschool.com/sites/default/files/styles/article_wide/public/light.png?itok=qAVLLxCG)
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-02-09, 02:26:00
damn, you guys have been going ham since my last visit. Big thank you to Fluss for all the testing, really appreciate it! That photo is my staple for render testing!
Title: Re: dubcats secret little hideout
Post by: sebastian___ on 2018-02-09, 02:59:08
Very interesting the real photograph, too bad it has light bouncing from bellow and it's a little harder to compare the lower area, because it's standing on a white plane.
Title: Re: dubcats secret little hideout
Post by: worx on 2018-02-09, 03:49:57
Is there a way to replicate defuse roughness in corona? Because i also find corona being a little flat, and really have to use post to get that soft shading looking
Title: Re: dubcats secret little hideout
Post by: nkilar on 2018-02-09, 09:00:15
Great tests @Fluss ! :) I suppose I am late to the party when it comes to realizing that FStorm uses the Beckmann BRDF model. Huh. Thanks for the tests!
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-02-10, 17:58:58
Very interesting the real photograph, too bad it has light bouncing from bellow and it's a little harder to compare the lower area, because it's standing on a white plane.

You are right. That and also the fact that the studio setup should produce way softer shadows than the HDRI used in the tests which should greatly influence the shadow terminator on the sphere. I'm gonna reproduce the setup to see how it behaves in Corona.

Anyway, after a lot of testing and observation, I think the diffuse roughness implemented in Fstorm is kind of weird. It shouldn't affect the diffuse that much, plus it does not affect what it is intended to. It gives a kind of coated material effect on every single shader created.

The PxrDisney shader affects both the diffuse at grazing angles and the shadow terminator, and it's much more subtle. BUT we lose control over the diffuse appearance as it's fully automated and there is no parameter exposed. It seems that they realized that since they have backtracked on that particular point. Indeed, the PxrDisney shader is already "outdated" and has been relegated to the legacy tab in the lastest Renderman version. It's still there but only for back-compatibility. They are now using the PxrSurface shader which is much more complex than the Disney one. The diffuse part is now pure Oren-Nayar. And I personally think it's the way to go.

In fact, I think CoronaMtl is not that far from the perfect shader, it just misses some features here and there.

To me, the perfect shader would probably be a carbon copy of the Alsurface shader + some features of the PxrSurface shader. This is what I'd go for :

_Better diffuse model (Oren-Nayar)

_An additional specular lobe. We will then be able to produce proper coated materials. WE NEED THAT. The CoronaLayeredMtl is.. well it's not a layered material, it's a blend material which is not the same. A proper layered material would allow us to stack multiple specular lobes in an energy conservative way, the top layers affecting the ones underneath.
At that point, with these only two features, the CoronaMtl would offer everything the Alsurface shader does. (minus the choice between Beckmann and GGX microfacets distribution).

I'd then add some nice features from the PxrSurface shader. Some of them are available following two modes, artistic/physical. I'd stick with the physical mode only :

_Layer thickness for the clearcoat: Everything is in the name, it simulates thickness for the additional specular lobe, really cool.

_Iridescence

_Fuziness: Full featured with gain, color, cone angle and bump. Not physically accurate but still nice to have

_Bump To Roughness: Insane feature! Basically,  it can use normal, displacement or even bump maps to affect microfacets distribution and anisotropy, in order to recreate surface imperfections in a way that is less prone to diverge according to the distance and produce more physically correct light interaction. (cf. paper below)

You can refer to the renderman documentation for more info on their surface shader: https://rmanwiki.pixar.com/display/REN/PxrSurface

And I strongly recommend you to read their recent paper on their material pipeline, really interesting: http://graphics.pixar.com/library/PxrMaterialsCourse2017/paper.pdf
Title: Re: dubcats secret little hideout
Post by: johnymrazko on 2018-02-14, 11:30:11
I was tired of the default material sphere that stretch materials all over the place. Here is a little guide on how to make a good looking material sphere.

Create a GeoSphere 50cm radius, since most scans nowadays are 1 meter.
128+ segments.
Type "Octa"

(https://i.imgur.com/DSHiuZ4.png)

Throw a "Spherify" on there just to be safe

(https://i.imgur.com/xCxtHAI.png)

Add a "UVW Map" "Planer" mode

(https://i.imgur.com/JR57ok8.png)

Default Sphere, nasty

(https://i.imgur.com/S7bjiDF.png) (https://i.imgur.com/wqMEWj8.png)

Box turned in to a sphere

(https://i.imgur.com/hDxnzfe.png)

GeoSphere with Planar

(https://i.imgur.com/W9XwCyk.png) (https://i.imgur.com/SKcK10w.png)

Hey dubcat

this shader ball works only when viewing from the front right? other views would be distorted if I am applying it correctly
Title: Re: dubcats secret little hideout
Post by: Juraj Talcik on 2018-02-17, 12:33:35
Great testing Fluss !!!

Sadly the issue isn't given much attention. It's all or nothing so currently it's volumetrics, and better shader and post-production will be 2020 I warrant a guess :- )
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-02-18, 15:54:41

Hey dubcat

this shader ball works only when viewing from the front right? other views would be distorted if I am applying it correctly

You can try with a simple box, no segments, with UVs -> turbosmooth with multiple iterations -> spherify

Great testing Fluss !!!

Sadly the issue isn't given much attention. It's all or nothing so currently it's volumetrics, and better shader and post-production will be 2020 I warrant a guess :- )

Yes I guess it's not the priority ATM
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-02-20, 17:58:36
Hey dubcat

this shader ball works only when viewing from the front right? other views would be distorted if I am applying it correctly

Hey man! Yes, it's only for Corona Material Thumbnail preview or as a preview for your Material Library.

------------------------------------

I've been taking my Megascans scripts to the next level the past week.
Yesterday I wanted to solve the whole translucency issue. We have a front lit albedo scan and a back lit translucency map scan. There should be no reason why we need to adjust these maps for the material to behave properly. I've solved the issue, and this is how translucency is taken care of in my latest script.

In Corona we have Translucency "Fraction" and "Color.
When Fraction is 0 it's pure diffuse, the material is black when back lit. When Fraction is 1, it's pure Translucency Color when back lit.
Translucency Color gets multiplied by Translucency Fraction.
Currently the script is using 0.5 Fraction to get 50/50. Translucency map is multiplied by 2, since 0.5 * 2 = 1.

(https://i.imgur.com/novBgfY.jpg)

(https://i.imgur.com/vVGEugq.jpg)

(https://i.imgur.com/UGitZ85.png)

As a little side note.
We can't disable IOR with a Corona Color anymore. I noticed this when I was explaining complex IOR.
You can see here that the last 10 degrees are getting darker. 89 degree is 232 RGB.

(https://i.imgur.com/ujOZs1Q.jpg)

edit: fixed a typo
Title: Re: dubcats secret little hideout
Post by: johnymrazko on 2018-02-20, 22:33:10
thanks for the reply

regarding megascans, if I would manually tweak the values without script to look correct it is rgb level 2.0 and translucency fraction 0.5 right?
Title: Re: dubcats secret little hideout
Post by: oddvisionary on 2018-02-20, 23:26:10
I just found a LUT converter in the newest official Megascans Bridge version by the way. Might be a bit late in the discussion or you already know it...
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-02-21, 00:32:09
regarding megascans, if I would manually tweak the values without script to look correct it is rgb level 2.0 and translucency fraction 0.5 right?
Yep :)

I just found a LUT converter in the newest official Megascans Bridge version by the way. Might be a bit late in the discussion or you already know it...

Hey!
That's my old LUT, it was hand made up to IOR 8 or something like that.
I've attached my latest version that was generated with code, it can remap any RGB value possible :)

edit:
Here is a test render using my improved IOR LUT.

(https://i.imgur.com/9jJtbkj.jpg)
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-02-27, 01:39:40
(https://i.imgur.com/VMuKWTs.jpg)
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-03-06, 15:58:48
I found a little hack to emulate how light get whiter in Corona.
We don't get that nice ACES color tint, but it's better than not having the effect.

Default Corona

(https://i.imgur.com/kYNNQnH.jpg)

My new VFB ACES emulation

(https://i.imgur.com/b6HyAxf.jpg)

Default Corona - Yellow Sun "bug"

(https://i.imgur.com/wTFtIxR.jpg)

Fix

(https://i.imgur.com/Cw3abT2.jpg)

I've attached the new settings file.
You only have to adjust exposure to your liking.

But stupid hacks like this wont be necessary if we get proper custom matrix.

Edit Edit:
Added v3 that is "Sun proof".
Title: Re: dubcats secret little hideout
Post by: vemod on 2018-03-06, 18:23:03
Or we could just make a stupid hack it at the light source instead :)

No perceptual color difference when viewed at regular exposure but it gets the "correct" overexposure behaviour.
I couldn't be arsed to replicate the grid completely, but you guys get the point.

Photoshop borked the colors as well, so try it with the supplied HDR values in a corona color that you plug in to the texture slot of a light.

It's generally a good idea to stay away from pure colors in CGI even when it comes to lights it seems :)
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-03-09, 01:58:26
To be honest I can't remember if I have posted this before, but people have been asking for it.
I have included my "Apply Image" script that makes a 1:1 highpass of your texture. This can be used on any texture, I mostly use it on diffuse and glossiness to make real time adjustments in Corona.

All the blending modes are in sRGB! (Something that is Corona exclusive for now!)

Open your texture map in Photoshop and run my attached script.
You will get this result.

Hide the bottom layer "albedo color" and save the "apply image high pass" map as a png or tiff.

(https://i.imgur.com/xap99HL.png)

Create a setup like this, where you sample the bottom layer as "Albedo" color.

(https://i.imgur.com/z7e9aiQ.png)

You can make a glossiness variant like this
But I usually normalize my glossiness map in Photoshop.

(https://i.imgur.com/BAHXce0.png)

Just remember that normal materials does not go bellow 0.4 glossiness. It is great that we have the opportunity to go down to 0. But just keep in mind that everything bellow 0.4 is for special occasions. If you have to fake depth, use an IOR map (Reflection Level clamp your IOR).
If you don't understand how how reflection level work, think of it like this. You have a black background layer in Photoshop, you have your IOR as a white layer above. If you reduce the "reflection level", its like you are reducing the opacity of the white layer in Photoshop. 89 degree will never be white!
Title: Re: dubcats secret little hideout
Post by: romullus on 2018-03-09, 11:05:19
Thanks a ton for you invaluable input to community dubcat!

I have a question about IOR map. What would be correct way to obtain such map? Let's say if i'd invert height/displacement map and ajust levels, so majority of colours would be at 170 RGB and cracks/identations would be white, approaching 255 RGB, would that make good IOR map?
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-03-10, 21:55:40
Hey

You have to make an AO map from your Normal map. There are multiple bakers out there that support normal map.

Substance Designer Baker with default settings.

(https://i.imgur.com/ru5KENW.jpg)

Substance Designer Node with default settings.

(https://i.imgur.com/SA8K8DW.jpg)

Quixel dDO with default settings.

(https://i.imgur.com/pHPhDIO.jpg)

I'm sharing my AO to Specular action.
I have split the action into 3 parts, so I can tweak values. No AO map is the same.
Remember to run them in the correct order!

(https://i.imgur.com/gzkaj6N.jpg)

(https://i.imgur.com/M2Qg2fB.jpg)
Title: Re: dubcats secret little hideout
Post by: A515 on 2018-03-11, 14:50:22
DUPCAT.. David Copperfield :)thank you
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-03-13, 09:21:31
I had a dream last night, I made a new IOR map generator. It supported IOR up to 1.8. So if you scanned a concrete wall or asphalt, the small stones would get higher IOR then 1.5.
If you have cross polarized a composition material before, you know what I'm talking about.
So the first thing I did today after some coffee, was to remake that generator, and it has basically changed the way I create PBR textures.

Here are some reflection tests

No IOR Map

(https://i.imgur.com/82PLBrq.jpg)

Official Megascans Specular Map converted to IOR

(https://i.imgur.com/bmI1xbR.jpg)

My new Generator.
You might notice the gem stones in the asphalt, and you can see how everything looks more defined and crisp.
It basically looks like a real cross polarized specular photo.

(https://i.imgur.com/FIxhqOR.jpg)
Title: Re: dubcats secret little hideout
Post by: WAcky on 2018-03-13, 09:45:15
Love seeing this thread progressing. Dubcat thank you for all the work. Do you have any recommended reading on getting started with creating one's own scanned materials? IE polarized lights/filters etc etc?

Cheers!

- James
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-03-13, 10:14:26
Do you have any recommended reading on getting started with creating one's own scanned materials?

Hey!

https://www.allegorithmic.com/blog/your-smartphone-material-scanner is a great starter guide.
They don't cover cross polarization. But if I remember correct, I made a how to on the forums somewhere.

You basically mount a linear polarizer sheet to your camera and light. Shot once, rotate the polarizer sheet on your light 90 degree, shot again.
One of the pictures contain "50% diffuse" and the other contains 100% specular + 50% diffuse.
Open both photos in Photoshop, convert to 32 bit mode (Need 32bit for correct linear math).
Subtract the "50% diffuse" photo from the "100% specular + 50% diffuse" photo, this is your spec map.
Take the "50% diffuse" photo and add it with itself once, this is your 100% diffuse map.

Repeat this process on all 4 angles, you end up with a nice albedo map and a glossiness map.
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-03-13, 10:36:00
Nice stuff Dubcat, as always !
Title: Re: dubcats secret little hideout
Post by: WAcky on 2018-03-13, 13:16:03
Magnificent. Thank you!

Do you have any recommended reading on getting started with creating one's own scanned materials?

Hey!

https://www.allegorithmic.com/blog/your-smartphone-material-scanner is a great starter guide.
They don't cover cross polarization. But if I remember correct, I made a how to on the forums somewhere.

You basically mount a linear polarizer sheet to your camera and light. Shot once, rotate the polarizer sheet on your light 90 degree, shot again.
One of the pictures contain "50% diffuse" and the other contains 100% specular + 50% diffuse.
Open both photos in Photoshop, convert to 32 bit mode (Need 32bit for correct linear math).
Subtract the "50% diffuse" photo from the "100% specular + 50% diffuse" photo, this is your spec map.
Take the "50% diffuse" photo and add it with itself once, this is your 100% diffuse map.

Repeat this process on all 4 angles, you end up with a nice albedo map and a glossiness map.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-03-13, 17:20:09
The new IOR generator is almost complete, this will be the final rev for today.

No IOR map

(https://i.imgur.com/wJd4Rne.jpg)

Old Specular to IOR map

(https://i.imgur.com/sp8pLh9.jpg)

New IOR Generator

(https://i.imgur.com/skgMtSt.jpg)
Title: Re: dubcats secret little hideout
Post by: fabio81 on 2018-03-13, 17:22:06
Dubcat can I ask you something ?
do you usually apply the lut file to a 32bit or 16bit file? because I noticed that Corona when applying the lut is as if it added a gamma 2.2 and then applies the lut above.
Now I do not know if programs like nuke or fusion should do the same thing or apply the lut directly above the 32bit.
how do you do with Nuke or Corona?

thanks!
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-03-13, 17:51:36
do you usually apply the lut file to a 32bit or 16bit file?

Hey!

If you are using Photoshop, convert the specular map to 16bit and apply the LUT. Load the bitmap as gamma 1.0

If you want to do everything inside 3dsmax, you have to load the specular map as gamma 1.0, use a ColorCorrection map to convert it to Linear, because of 3dsmaxs gamma mess. Apply the LUT, and convert it back to sRGB.

(https://i.imgur.com/6TzqYJb.png)

The new IOR generator is not a LUT. You can feed it scanned specular maps or old reflection level maps.
Will make a separate post on how to use it when it's ready.
Title: Re: dubcats secret little hideout
Post by: fabio81 on 2018-03-13, 17:59:22
thank you so much!
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-03-16, 17:07:33
The new generator is almost complete.
It can generate IOR and Specular maps from 3 different map inputs so far.

#1 Cross Polarization Specular Scan
This is the best solution, your Corona render will have identical reflections to the real world cross polarized specular map.

This is the result

(https://i.imgur.com/I8mgmst.png)

#2 Normal Map
This is the second best solution. If you don't have a cross polarized specular map, you can use this one.
You can use any existing normal map. It will generate a IOR / Specular map based on the normal map height strength.
This was initially Jurajs idea, and Ondra gave me some pro tips. So this generator would not exist if not for them!

This is the result

(https://i.imgur.com/5LxnkKI.png)

#3 Reflection Level
This is the shittiest last solution.
It will convert old reflection level maps to IOR/Specular. This will give you the same look as you had before, but it will not clamp fresnel.

Since the new generator also generate specular maps, we get real world reflection behavior in Unreal 4!

(https://i.imgur.com/mHFyb8a.png)

When everything is road tested and tweaked, I will compile them as 3 LUTs.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-03-16, 23:02:16
Thought I could share my custom metal settings. It's nice to get the correct scanned behavior from "refractiveindex.info", but the color values are way off. These are my current reference matched metal materials, these change every week, so it's more of a snapshot of my current settings.

(https://i.imgur.com/AX8KW6r.png)

(https://i.imgur.com/jb5mmPH.png)

(https://i.imgur.com/SNTyRwd.png)

(https://i.imgur.com/rdZz1GH.png)

(https://i.imgur.com/vQALe2z.png)

(https://i.imgur.com/gcyhYYC.png)

(https://i.imgur.com/OPtrJbi.png)

(https://i.imgur.com/OJiSv4k.png)

(https://i.imgur.com/NCPtBYE.png)

Gold Example:

(https://i.imgur.com/Li9qNsq.jpg)(https://i.imgur.com/7yWBMrK.jpg)
Title: Re: dubcats secret little hideout
Post by: Basshunter on 2018-03-20, 05:08:32
Hi @Dubcat, very interesting topic. So, this "Specular map" would be used as Glossiness map right? And reflection slot full white?
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-03-21, 16:27:28
"Specular map" would be used as Glossiness map right? And reflection slot full white?

Hey!
The IOR map is used in the "Fresnel IOR" slot and complements the glossiness map. They are both generated from the same cross polarized set of pictures.
Current PBR shaders can't emulate real world materials with just albedo/glossiness.
If you build a virtual material scanner inside Corona and scan your materials, you will see that the cross polarized specular does not represent real world at all.
My new IOR generator takes care of this problem.

Here are some examples from my last virtual 3d scanner test.

This is how I generate my maps

(https://i.imgur.com/U8DebaK.jpg)

No IOR map Specular

(https://i.imgur.com/1FeMQAA.jpg)

IOR map Speulcar
(https://i.imgur.com/GedhM6A.jpg)

Glossiness map generated from the material with no IOR Map

(https://i.imgur.com/GwUPmod.jpg)

Glossiness map generated from the material with IOR Map

(https://i.imgur.com/wFEozGv.jpg)
Title: Re: dubcats secret little hideout
Post by: mferster on 2018-03-21, 23:10:41


If you build a virtual material scanner inside Corona and scan your materials, you will see that the cross polarized specular does not represent real world at all.

Wait, wait, wait! How did you simulate a cross polarization filter material in corona?
Title: Re: dubcats secret little hideout
Post by: karnak on 2018-03-22, 09:25:46
@mferster

In Corona you don't need cross polarization to split diffuse reflection from specular reflection. You have render elements for that.
Conversely, in real-world you need cross polarization because your capture equipment (i.e. your camera) most likely won't have render elements. :D

I think dubcat is saying that when you compare the render element to the real-world cross-polarized photo, the two don't match at all.
He is using a method for processing scanned data, but looks like the inputs in his test are from Corona so he can iterate and change things faster.
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-03-22, 09:33:52
Looks great Dubcat! Some questions comes to my mind:

How can you extract specular values from a normal map?
I guess you basically linearly remap the "height" infos of the normal map, keeping the reflectance between the 2-5% range at F(0°), but that way, I can't understand how it can be better than a map derived from a reflection map which contains "proper" lighting pieces of information compared to a normal map.

Reflection and Specular maps are sRGB bitmaps (gamma 2.2) while normal maps and IOR maps are Linear (gamma 1.0), How is that handled?

Hey!
The IOR map is used in the "Fresnel IOR" slot and complements the glossiness map.

I a bit confused on the difference between IOR and Fresnel IOR inputs. Can you explain what properties are defined by each of those?
Title: Re: dubcats secret little hideout
Post by: mferster on 2018-03-22, 16:03:41
@karnak

Yes, I am aware of how render elements work, thanks karnak. It looks like I misinterpreted what he wrote and got excited at the idea of simulated cross polarization filters.
Title: Re: dubcats secret little hideout
Post by: karnak on 2018-03-22, 17:16:56
That was just my interpretation of what he wrote, and I hope I didn't accidentally offend you with it. :)
Title: Re: dubcats secret little hideout
Post by: mferster on 2018-03-22, 18:18:15
It's all good, I think you are quite right, that is indeed what he is doing.

But now it has lead me down a rabbit hole of experimentation to see if it is actually possible to simulate cross polarizing filters in Corona (or fake it atleast).
Title: Re: dubcats secret little hideout
Post by: karnak on 2018-03-22, 19:45:50
Me too and I'm also excited about OSL in 3dsmax2019. A lot of stuff to experiment with! :D
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-03-23, 00:46:54
Wait, wait, wait!

Hey!
Create a "CShading_Components" pass and disable "Indirect". This should give you the same result as we get from cross polarizing and subtracting.
When we capture materials in real life, we use fast shutter speeds like 1/400+ to kill ambient light. We only want the direct flash/softbox light.

How can you extract specular values from a normal map?
I guess you basically linearly remap the "height" infos of the normal map, keeping the reflectance between the 2-5% range at F(0°), but that way, I can't understand how it can be better than a map derived from a reflection map which contains "proper" lighting pieces of information compared to a normal map.

Reflection and Specular maps are sRGB bitmaps (gamma 2.2) while normal maps and IOR maps are Linear (gamma 1.0), How is that handled?
Hey!
You are pretty much spot on.
In a perfect world we generate a 4+ point specular scan of a material, and run it through my generator. I only do Arch Viz and 80% of my texture library is still old school "non scanned".
By extracting height data from old school normal maps, we can at least fake depth somewhat. It's still better then not having any depth emulation at all.
And as a last resort, we can convert old reflection maps to IOR. This can be nice for wood materials, where we have to emulate the wood tubes that go in different directions. When we don't have a specular/normal map, and we don't want to use "Reflection Level" to clamp the Fresnel. "Reflection Level" is pure evil! (As a side note, pleeeeeeeeaaaase Ondra, can we get a Wood Material ?, http://www.cs.cornell.edu/~srm/publications/SG05-wood.pdf)

I a bit confused on the difference between IOR and Fresnel IOR inputs. Can you explain what properties are defined by each of those?
To be honest I have never done any research if the "Refraction IOR" behaves differently from "Diffuse IOR" in Corona, they should be the same. Most engines only have one IOR that control both diffuse and refraction.

---------------------------------------------------------------------------------------------------------------

Every now and then I get PMs from people that are really interested in materials and CG in general.
I use my Skype at work, so I can't add everyone there.
I've made a new Discord server that will be invite only, but everyone can join.
Send me a PM, and I will send you an invite.
Title: Re: dubcats secret little hideout
Post by: Basshunter on 2018-03-28, 17:22:02
Hi @dubcat. I recently discovered this thread and I must say everything that has been talked here is SO interesting! However, as a new Corona user I feel a little lost when trying to find the beginning and conclusion of the topics. Is there any way to easy access files, pictures or written conclusions resulting from the topics treated? Maybe another thread?
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-03-31, 23:51:42
Hi @dubcat. I recently discovered this thread and I must say everything that has been talked here is SO interesting! However, as a new Corona user I feel a little lost when trying to find the beginning and conclusion of the topics. Is there any way to easy access files, pictures or written conclusions resulting from the topics treated? Maybe another thread?

Hey!

I will consolidate everything here http://dubcats-secret-little-hideout.wikia.com/wiki/Dubcats_secret_little_hideout_Wiki (http://dubcats-secret-little-hideout.wikia.com/wiki/Dubcats_secret_little_hideout_Wiki), it will take some time before the wiki gets refined and contain everything.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-04-11, 15:33:15
Paint manufacturers "fake" the brightness of darker colors on swatches. Luckily we can get measured "Light Reflectance Value" of the actual paint online.
The swatches also include IOR from what I understand.

Juraj sparked some ideas in my head yesterday, and last night I had a dream where I made a LUT that convert swatches to albedo.
The LUT will remove fake brightness and IOR from the swatches.
The more color samples I have, the more accurate the LUT will be.

I will share the LUT when it has at least 100 swatches, and then keep posting updates as I add more colors.

Here is an example of what it will do

(https://i.imgur.com/5DNEBVp.png)
Title: Re: dubcats secret little hideout
Post by: peterguthrie on 2018-04-11, 18:15:12
I love your dreams dubcat :)
Title: Re: dubcats secret little hideout
Post by: mferster on 2018-04-11, 18:33:14
Dubcat's dreams are the best dreams. I wish my dreams were as productive.

*edit: So on a general bases what's the translatable value from a swatches Light Reflectance Value to a material's Albedo or IOR?
Title: Re: dubcats secret little hideout
Post by: Dippndots on 2018-04-11, 18:52:36
Where did you get these swatches from originally dubcat? Color picking from manufactures' websites?
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-04-11, 21:09:11
I love your dreams dubcat :)

hehe :)

So on a general bases what's the translatable value from a swatches Light Reflectance Value to a material's Albedo or IOR?

+

Where did you get these swatches from originally dubcat? Color picking from manufactures' websites?

Most painters in Norway use Jotun (https://www.jotun.com/no/no/b2c/colour-inspiration/colours/), so I sample my colors there.
They have a new 2018 set, that sparked the whole conversation with Juraj and Daniel R.
I can do a quick example. Lets use a dark color, since bright colors swatches are pretty accurate, we only need to remove 4% IOR from bright values.

Lets say someone want this dark brown NORWEGIAN WOOD 10981 (https://www.jotun.com/no/no/b2c/colour-inspiration/colours/interior/10981-norwegian-wood-interior.aspx)

You sample the manufacturers value

(https://i.imgur.com/RcWDLGa.png)

This color is #7f5c47

We go to e-paint (http://www.e-paint.co.uk/Convert_RGB.asp) and search for #7f5c47, because we don't know what the international standard name is.
The search result tell us that this color is part of "AMS Standard 595A -  Brown international"
And that the scanned LRV aka "Light Reflectance Value" is 13% Linear.

We can try to check the LRV of our current sampled value. But if we disable sRGB in "Corona Color Picker", we still get sRGB "Value" in Corona. I have made a requested that "Value" should be affected by the sRGB toggle, but I don't think it will happen. Maybe if enough people bug the devs about it, we can get this feature. It's really important.

(https://i.imgur.com/QlC0usR.png)

Since "Corona Color Picker" "Value" is not linear, we have to do some side stepping.

Disable "sRGB", go to "0-100%", input 13.

(https://i.imgur.com/0maT0L4.png)

Enable "sRGB" again and go back to "0-255".

(https://i.imgur.com/RWFKoLJ.png)

Copy the Red value in this case 101.

Go back to our sampled color, and paste 101 into "Value"

(https://i.imgur.com/TItGRYK.png)

We have now converted this preview swatch into real world LRV. But from my understanding this value still contain 4% reflectance from IOR 1.5.
But really, no one will notice this 4%. But I can't sleep well at night, knowing that I apply IOR 1.5 twice. And this is why you are one step ahead og the rest.

This is where I use pure white in "Environment Background", create a plane. Look straight down at the plane in orthographic. Use 1.5 IOR and 1 Glossiness (GGX glossiness will mess this up, if you use anything bellow 1). Then adjust "Value" until the sRGB match the original corona color value.

In our current case, this is what we get in IR with the corrected sampled color.

(https://i.imgur.com/FjVZ6tT.png)

The brightest color is 113 sRGB. Because we have to deal with IOR.

But the brightest color in our sample is 101 sRGB, and these guys have to deal with IOR in real life too.

So we have to adjust our sample down to 87, 64 ,50.

(https://i.imgur.com/6D003uf.png)

Sometimes the darker colors change hue and saturation when you do drastic changed like this, you can manually correct this. But my LUT will take care of all this mess. The LUT is not generated in sRGB space.

TLDR; Just remember to give the devs a little PM that you want the sRGB toggle to affect "Value" in "Corona Color Picker", features like this depend on you!
Title: Re: dubcats secret little hideout
Post by: IsmaeL on 2018-05-22, 14:40:57
This is exactly the stuff I dream about XD

Just made a bathroom furniture catalogue and color is a major issue. The client uses NCS and we had to adjust everything in Post to match print and swatches. Just horribly painful.
So I'm glad to see I'm not the only one annoyed by the Corona Color Picker.

It would be so nice if we could get the Cinema Color Picker, it is very elaborate and useful.

Talking about color, maybe we could ask the devs to automatically load the screen color profile into the Corona Frame Buffer. Because right now calibrating my screen is not very useful in Corona.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-07-06, 02:53:11
I was having a chat earlier this year about HDRi and Corona Sun/Sky. Theres been lots of stuff happening in RL, so I haven't had much time to be active online (both forum and discord). I thought this stuff might be interesting for some people, so lets recap.

I made the switch from Vray to Corona back in 2015, and one of the first things I noticed was that everything felt "orange". I'm talking about VFB 6500K white balance.
I can't express how good it was to drop that damn green vray usb dongle that kept disconnecting every 10 min, sometimes mid render.

Earlier this year, people were going crazy on social media about HDRi, how good HDRi light was. They said stuff like, if you want smooth shadows, you must use a HDRi.

So earlier this year, I wanted to answer two questions. Why do I feel Corona is orange, and why do 90% of the world prefer HDRi skies.

I live in Scandinavia and I know that the strongest sun is at 12:00 6/21/2018. This gives us a latitude of 59.917.
The closest HDRi I could find online was Peter Guthries 1216 Sun Sky which is 58 degree.

Peter has been a good boy and updated his skies with a calibrated sun, but I wanted to keep the original camera sun values. So I will be using the original HDRi which he also provide.

Peters 1216 Sun sky is pretty much perfect, but as with any real world HDRi captures, there will be sun flare. We have to isolate the sun from the sky. And the sky has to be isolated from the sun flare.

We have to base our test on something, or else it would be random values. As usual I will be using 18% grey on my test subjects, this is 117 sRGB. Corona sun will be matching Peters HDRi angle, about 58 degree. Corona sky is a dynamic map, it will change color and gradient based on the sun position. We will change "Horizon blur" to 0 and Ground "color" to black, to match Peters HDRi.

The first thing we have to do is calibrate our "camera" aka VFB. We are using Corona Sun and Sky with default settings.
We know our test subject is 18% grey aka 117 sRGB. We have to lower EV in VFB to -5.24 for our test subject to meet 117 sRGB.
-5.24 EV will be our base for the rest of this test.

(https://i.imgur.com/9u1cvRa.jpg)

Our next step is to isolate the Sun from the HDRi, I will do this inside 3dsmax with this mask.

(https://i.imgur.com/WKcnHaU.jpg)

When we isolate the sun from the sky, this is what we get. Remember that this is the original camera capture. Peter provides a calibrated sun version when you purchase the HDRi. Most companies will only provide the "Photoshoped" perfect version, but Peter is keeping it real. If your monitor is not calibrated, it will show up as black.

(https://i.imgur.com/AGKv62w.jpg)

If we boost the HDRi "RGB Level" to 520, we will match our calibrated Corona Sun value.

(https://i.imgur.com/D7nM27D.jpg)
(https://i.imgur.com/f3uMO7s.jpg)

This calibration phase has to be done with any HDRi. It doesn't matter if its CG-Source, PG Skies or anyone else. No real world commercial camera can capture the real world sun value in a HDRi. Most people use the 0.8 gamma trick, this trick will boost your sun value a tad bit, and mess your sky values up like there is no tomorrow! The best way to handle real world HDRis, is to isolate the sun from the sky and calibrate them separately, because the values are so far apart.

I've been splitting sun/sky on a bunch of real world HDRis and on average the sky is "the sun RGB Level" / 100. In our case that is 520 / 100 RGB = 5.2 RGB.

I had to mask the sun flares on this render to calculate the values.

(https://i.imgur.com/Xz2YF0E.jpg)

We have our Peter Sun/Sky split and calibrated. It's time to match Corona Sun/Sky to our real world captured data.
Lets start with the sun.

Our first goal is to match the "softness of the sun", 2.5 Corona sun size does the trick.
Our next goal is to match the RGB. When we switch to "Direct Input" aka 1.0 White Sun. 1 sun intensity does not give us 1 intensity in the render. So we have to boost the Sun intensity to 1.12 (Corona error?).
To match the sun RGB we have to change Red to 254 and Blue to 252.

(https://i.imgur.com/nHtIfbq.jpg)

This is what we get if we just isolate the sun from the HDRi and do not remove the lens flare. It's kind of crazy how much lens flare affect the render. Since lens flares have much lower value than the sun, it will help generate smoother shadows. So maybe I judged those social media people too soon.

(https://i.imgur.com/SfOZ5UD.jpg)

If we remove the lens flares, we get this from the HDRi. You can see all the direct shadows from the lens flare is gone.
This is what we base our Corona Sky on.

(https://i.imgur.com/d3hMZHG.jpg)

To get a close match we have to use "Turbidity" 1.7 (1.7 does not satisfy the Peter capture, maybe 1.5 would, but we can't try)  and these values inside a "Color Correction". Color Correction is linear so 1 * 2 would result in 2.

(https://i.imgur.com/nLMRwFz.jpg)

This is how Peter Guthries 1216 Sun looks calibrated

(https://i.imgur.com/xXo0T1y.jpg)

With our quick approximated values, Corona Sun/Sky looks like this.

(https://i.imgur.com/dKysxb0.jpg)

So in the end. Even small lens flares from real world captured skies will give you more "detailed" skies. Since you mix the sun with less valued light sources. If you capture a sky with clouds, the clouds will in most cases go above +1 RGB. Resulting in more soft light sources.
Most HDRis will have white balanced suns. But if you use Corona Sun "Realistic" it will give you an "Orange" look.
Title: Re: dubcats secret little hideout
Post by: arqrenderz on 2018-07-06, 03:52:02
Just WOW to the last dubcat post, you know a lot of this.
Where can u normal user start, in order to better understand all this concepts?
Title: Re: dubcats secret little hideout
Post by: piotrus3333 on 2018-07-06, 11:11:55
finally. thx for educating people about flares on hdris.
another thanks for all of you guys chasing fstorms tone mapping. great work. I'm spending more and more time on this forum because of content like that.

quick question about paint color samples: why subtract 4% form 13% LRV when corona's mat does energy conservation for you?
and what about doing it with composite map from max? (attached). 13% gray map and color sample on top in "color" blend mode plus maybe lowering saturation a bit in some cases (oversaturated samples made looking nice on screens)
Title: Re: dubcats secret little hideout
Post by: johan belmans on 2018-07-06, 11:34:41
@Dubcat: Thanks for sharing!
Title: Re: dubcats secret little hideout
Post by: Juraj Talcik on 2018-07-06, 12:36:51
quick question about paint color samples: why subtract 4% form 13% LRV when corona's mat does energy conservation for you?

I have found this to be very arbitrary ad-hoc introduced in Corona shader. It was done long time ago as quick-fix for people over-doing bright albedo.
It's not part of the energy conservation model but additional part on top. Perhaps the devs could show what exactly it does because I haven't found it to correlate with 4perc (the most common base reflectance of insulator).
Title: Re: dubcats secret little hideout
Post by: piotrus3333 on 2018-07-06, 13:12:56
4% or 24% does not matter as long as diffused reflections are dimmed by direct ones. that looks ok to me in Corona but I also never bothered with side-by-sides.
Title: Re: dubcats secret little hideout
Post by: karnak on 2018-07-06, 15:04:08
Let's say that the color was sampled with a spectrophotometer. What you get from that instrument is one reflectance value that contains both diffuse and reflection (with no distinction). So, if you want only the diffuse you have to know the reflection value and subtract it from the value the instrument gave you.

When you read that you have to subtract 4%, it's because they assume the color was sampled from a non-metal surface with the default 1.52 IOR (that at normal incidence equals 4%).
Title: Re: dubcats secret little hideout
Post by: piotrus3333 on 2018-07-06, 15:29:08
correct me if Im wrong but „Diffuse” in corona mat describes total reflectance (diff + direct). when you add „Reflection” on top of that Corona dimms diffuse part to balance the energy.
Title: Re: dubcats secret little hideout
Post by: piotrus3333 on 2018-07-06, 15:40:22
...dimms „Diffuse” part to balance the energy.
Title: Re: dubcats secret little hideout
Post by: Juraj Talcik on 2018-07-06, 17:08:48
correct me if Im wrong but „Diffuse” in corona mat describes total reflectance (diff + direct). when you add „Reflection” on top of that Corona dimms diffuse part to balance the energy.

No, the Diffuse in CoronaMTL is only the diffuse albedo part, not total albedo (Diffuse reflection albedo+ Specular reflection albedo). Second part is correct about Energy Preservation.

But energy preservation in shader doesn't account for scanned F0 values. There is some arbitrary deduction from early version ( two years ago ?) done on diffuse but this is done on top and it's just hack.
It does basically the same thing, reducing the diffuse albedo slightly even before specular is applied. The amount is smaller than 4perc. though.

Same goes for using photometric stereo scanned textures. Energy preservation will only kick afterwards but for the shader to recreate exact albedo you need to feed the diffuse slot only pure 100perc. diffuse albedo.
( additional cross-polarization scan to extract specular scan and then the classic 50perc. negation to get pure diffuse albedo).
Title: Re: dubcats secret little hideout
Post by: piotrus3333 on 2018-07-06, 18:24:00
all clear, thank you.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-07-08, 02:22:05
what about doing it with composite map from max? (attached). 13% gray map and color sample on top in "color" blend mode plus maybe lowering saturation a bit in some cases (oversaturated samples made looking nice on screens)
Hey man!

I've tried to do this procedure in RGB, but it's just not possible. Paint companies just love to boost those dark colors in their previews, and keep the bright colors somewhat correct to the LRV.
My workflow is to calibrate as much as I can to a color checker, and use real world light values. This gives me a dull and boring raw render with bright burning light spots. My post settings give these ugly raw renders the "larger than life" feeling. This is just my workflow though, I'm not hating on people who like to get good results with raw renders.

The reason I use 1 filmic HC in my ACES VFB hack is because filmic make our max white 255 RGB. We exploit this with our standard Corona HC setting, and reduce it bellow 1. This will boost our whites and give us that nice pop.

Juraj and karnak has been nice and answered all the 4% IOR questions :)
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-07-12, 04:51:24
At some point in your archviz career, someone will request a cross fit machine in their render. I had this terrible experience back in 2014.
The elephant in the room is the hybrid metallic paint. How do you deal with it ?

The reason I want to mention this, is because I had to relive my 2014 nightmare a couple of weeks ago. We could counter this problem with metalness workflow. Chaosgroup has already implemented this workflow in Vray Next.

In our current situation you want to make a material like this. This could be done in one map if we had metalness, and we could discard the falloff map.

(https://i.imgur.com/m5zlKuJ.jpg)

(https://i.imgur.com/zEG3vKi.jpg)

edit:

The kind of noise you want to use.

(https://i.imgur.com/tgbrTc7.png)

Red is plastic and green is metallic

(https://i.imgur.com/ojqgLlJ.jpg)
Title: Re: dubcats secret little hideout
Post by: IsmaeL on 2018-07-12, 09:38:40
Interesting material. Looks very nice.
I thought it's just paint with a higher IOR but never had to make this one before so my opinion doesn't count XD

What does  the metalness map look like. I seams just white.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-07-12, 19:48:26
What does  the metalness map look like. I seams just white.

Hey man
Updated the post with noise samples.
Title: Re: dubcats secret little hideout
Post by: maru on 2018-07-13, 14:05:29
You can map Fresnel IOR so wouldn't it be possible to make this with just a single material?
Title: Re: dubcats secret little hideout
Post by: Jpjapers on 2018-07-13, 14:24:15
Could you show an example of the material youre recreating?
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-07-13, 14:29:21
You can map Fresnel IOR so wouldn't it be possible to make this with just a single material?
Yes, I would have done it that way. I don't really like the pure metalness workflow tbh, metallic IOR is not exposed and that's a no-go for me. I just hate the Hardcoded stuff!
Title: Re: dubcats secret little hideout
Post by: Njen on 2018-07-13, 19:47:30
You can map Fresnel IOR so wouldn't it be possible to make this with just a single material?

As long as you are able to treat the dielectric and metallic surfaces differently with the same mask in regards to reflection and diffuse colour it is theoretically possible. But it's just easier to do it with two materials because there would be less nodes to use (less mixes).
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-07-13, 20:23:46
You can map Fresnel IOR so wouldn't it be possible to make this with just a single material?

Hey!

Everything is possible with enough maps.
In this case we have metal flake bits that range from fully covered in paint to not covered at all.
It was easier to control the paint coverage by blending the materials together with random noise values.

Could you show an example of the material youre recreating?

Hey!

It's this type of paint.
If you cross polarize the material, you will notice white spots (metal) in the specular map.
I made the noise size larger in the preview material to make the effect more noticeable.

(https://i.imgur.com/9EizGKy.jpg)


I don't really like the pure metalness workflow

Hey!

I don't like pure metalness workflow either.
Vray has a really nice implementation. Metalness is 0 by default, no one will notice it's there.
But if we need it, we can change it to 1. Win win.

(https://i.imgur.com/vnZx9SL.jpg)

As long as you are able to treat the dielectric and metallic surfaces differently with the same mask in regards to reflection and diffuse colour it is theoretically possible. But it's just easier to do it with two materials because there would be less nodes to use (less mixes).

Right on!
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-07-14, 15:34:34
Here's the first public "Roughness to IOR" LUT test.

Since slate and LUTs are a complete gamma mess, I have embedded all the gamma conversion stuff inside the LUT.

How to:
01. Open the roughness map in Photoshop.
02. Run my high pass action script. This script uses "Apply Image" to generate a perfect 1:1 High pass. It does not use the terrible Photoshop radius based High pass.
03. Load the map inside 3dsMax with "Auto Gamma".
04. Plug the map into "Corona Color Correct" and load the LUT.
05. Plug "Corona Color Correct" into "Fresnel IOR".

(https://i.imgur.com/4ATgg7Y.jpg)

Examples, best enjoyed in a new tab.

(https://i.imgur.com/uJBDBfp.jpg)(https://i.imgur.com/f0LdSK1.jpg)

(https://i.imgur.com/gyFsLr0.jpg)(https://i.imgur.com/7BazNsr.jpg)

I have made a High pass filter inside Corona, when I get around to code the new Bridge scripts, you won't even have to deal with Photoshop. In an ideal situation we would get a high pass Corona map, since it's a must when it comes to scanned textures.
Title: Re: dubcats secret little hideout
Post by: Basshunter on 2018-07-16, 04:03:41
Here's the first public "Roughness to IOR" LUT test.

Hi Dubcat,

will you add this info to the Wiki site? It'd be easier to understand for people who haven't followed this from the beginning (Me included)

Thanks for all your knowledge.
Title: Re: dubcats secret little hideout
Post by: Jpjapers on 2018-07-16, 10:20:31
Quote
Hey!

It's this type of paint.
If you cross polarize the material, you will notice white spots (metal) in the specular map.
I made the noise size larger in the preview material to make the effect more noticeable.

(https://i.imgur.com/9EizGKy.jpg)


Ah right that kind of plastic dipped metal stuff?
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-07-21, 22:31:04
will you add this info to the Wiki site? It'd be easier to understand for people who haven't followed this from the beginning (Me included)
Of course, I will add it to my todo list :)

Ah right that kind of plastic dipped metal stuff?
Yes something like that :)

------------------------------------

I will be dumping Camera Profiles until the sun comes up today.
Here is a dump of Phase One - IQ3 100MP it "only" cost 50 000$.
I would recommend that you use "Filmic Highlights" 1 as a starting point when using Camera Profile dumps. And then season to taste, because "Filmic Highlights" at 1 will remove everything called highlight. So either reduce "Filmic Highlights" OR if you want to boost the highlights a little, reduce "Highlight Compress" bellow 1, but this will also add contrast. Keep that in mind.

OR everyone could request ACES with at least five parameters:
Slope           - Controls the overall curvature strength.
Toe              - Controls the bottom half of the curve.
Shoulder      - Controls the top half of the curve.
Black Clip     - Moves the left anchor point below 0.
White Clip    - Moves the right anchor point above 1.

But stuff like this only exist in my dreams and Unreal 4.

edit:
So I have dumped a few cameras now, ranging from expensive mobiles, "cheap" cameras to expensive cameras.
Mobiles and "cheap" cameras have a tendency to crunch blacks and boost saturation. While expensive cameras tend to desaturate a little and keep the black crunch to a minimum.
All the devices boost mid/high, and in most cases the center point of the curve is shifted to the left (What Camera Raw 9.9 2010 has been doing all along). 32bit support has been dismissed by Adobe, so RIP 32bit Camera Raw. GG Adobe!

------------------------------------

Waiting for the 18% grey paint to dry.

(https://i.imgur.com/esW0jFn.jpg)
Title: Re: dubcats secret little hideout
Post by: aldola on 2018-07-23, 21:29:02
great! will test
Title: Re: dubcats secret little hideout
Post by: aldola on 2018-07-23, 21:47:57
give me a canon 5ds :p
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-07-23, 23:44:51
give me a canon 5ds :p

Here is Canon 5DS RGB dump. I'm currently not 100% satisfied with my HSL dumper, will hopefully fix it next weekend.
Title: Re: dubcats secret little hideout
Post by: aldola on 2018-07-24, 00:08:33
thanks! i will try it
Title: Re: dubcats secret little hideout
Post by: aldola on 2018-07-24, 15:41:51
here is a test with the 5ds dump, this is the correct way to use them? may be the higlights are too strong
Title: Re: dubcats secret little hideout
Post by: fabio81 on 2018-07-24, 16:08:47
wow! very beautiful the LUT of the Canon 5dS!
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-07-24, 17:39:14
here is a test with the 5ds dump, this is the correct way to use them? may be the higlights are too strong

I did a quick comparison against default ACES.
You have to use "Highlight Compress" 2.5 and "Filmic Highlights" 1 to match default ACES.
So leave "Filmic Highlights" at 1 and adjust "Highlight Compress" from 2.5 to taste.

edit:

I forgot to say that these settings only count for the Canon 5DS dump.
Title: Re: dubcats secret little hideout
Post by: johnymrazko on 2018-07-25, 14:07:51
Hi dubcat

regarding calibrating hdris - is it neccesary to do even if I use separate light source (Corona Sun) for direct light? - for example noemotion hdris have no shadows from the sun
Title: Re: dubcats secret little hideout
Post by: aldola on 2018-07-25, 15:44:31
Hi, i use this 

https://3dcollective.es/producto/hdri-22pack-pro/


 i think the best quality on the market, no strange tint on the colors and the have very good dinamic range.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-07-25, 19:44:01
regarding calibrating hdris - is it neccesary to do even if I use separate light source (Corona Sun) for direct light? - for example noemotion hdris have no shadows from the sun

Hey!

I would still adjust RGB Level to match Corona Sky values at least. Corona Sun will eat all the sky light from those low exposure HDRis.
And just to be sure, I would remove the low level sun. It will only get stronger if you adjust RGB Level.

If we combine Corona Sun and this NoEmotion HDRi without increasing the RGB Level, we won't even notice the HDRi.

(https://i.imgur.com/dDLZ81n.jpg)

If we do a quick sky calibration like this.

(https://i.imgur.com/UUNiJcm.jpg)
(https://i.imgur.com/i5LP10M.jpg)

We can finally see the HDRi again.

(https://i.imgur.com/sDcXCq5.jpg)
(https://i.imgur.com/D2BM8eb.jpg)


------------------------------------------------------

I had a quick look at the free sample 3DCollective HDRi.

Looks like someone painted the sun with a large soft brush.
The sun value is 1079 times dimmer then Corona Sun.

(https://i.imgur.com/jpxqtjG.jpg)

Here is Corona Sun for size comparison

(https://i.imgur.com/vdNdIf1.jpg)

(https://i.imgur.com/hsWr0iM.jpg)
Title: Re: dubcats secret little hideout
Post by: Njen on 2018-07-25, 20:55:35
A general rule of thumb when processing HDRI's, or using something downloaded from the internet, it is important to know that at the equator, at 12pm noon, the sun is roughly 100,000 brighter than the average area of a large patch of sky. So as the sun gets lower in the horizon, the brightness of the sun decreases just a little because light has to travel through more atmosphere. And if there is any form of high level cirrus cloud, the brightness is decreased a tiny bit more too.
Title: Re: dubcats secret little hideout
Post by: aldola on 2018-07-25, 21:13:22
They are calibrated to use with the camera so 3DCollective_HDRi_022_1722_+8_4K the +8 means that you have to give +8 rgb  output amount to give the correct intensity, this one is a cloudy sky, the sunny ones have a +32 output value.

i dont know if they are correct but they give some nice shadows with the sun.

Adan martin  the creator is on the forum, so i think he can give a more correct explanation
Title: Re: dubcats secret little hideout
Post by: johnymrazko on 2018-07-25, 21:32:51
regarding calibrating hdris - is it neccesary to do even if I use separate light source (Corona Sun) for direct light? - for example noemotion hdris have no shadows from the sun

Hey!

I would still adjust RGB Level to match Corona Sky values at least. Corona Sun will eat all the sky light from those low exposure HDRis.
And just to be sure, I would remove the low level sun. It will only get stronger if you adjust RGB Level.

If we combine Corona Sun and this NoEmotion HDRi without increasing the RGB Level, we won't even notice the HDRi.

(https://i.imgur.com/dDLZ81n.jpg)

If we do a quick sky calibration like this.

(https://i.imgur.com/UUNiJcm.jpg)
(https://i.imgur.com/i5LP10M.jpg)

We can finally see the HDRi again.

(https://i.imgur.com/sDcXCq5.jpg)
(https://i.imgur.com/D2BM8eb.jpg)


------------------------------------------------------

I had a quick look at the free sample 3DCollective HDRi.

Looks like someone painted the sun with a large soft brush.
The sun value is 1079 times dimmer then Corona Sun.

(https://i.imgur.com/jpxqtjG.jpg)

Here is Corona Sun for size comparison

(https://i.imgur.com/vdNdIf1.jpg)

(https://i.imgur.com/hsWr0iM.jpg)

Thanks for the reply. What values did you use for sun and sky ? default size and intensity for both? sun in realistic mode? Framebuffer rule of -5,24 exposure from PG skies calibration probably doesn´t apply here or am I wrong?
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-07-25, 21:52:49
Thanks for the reply. What values did you use for sun and sky ? default size and intensity for both? sun in realistic mode? Framebuffer rule of -5,24 exposure from PG skies calibration probably doesn´t apply here or am I wrong?

I left everything at default settings and just aligned the sun to the HDRi sun. This particular sun angle needed -5.285 EV for true albedo.
Corona Sky is a dynamic map that changes once you add a Corona Sun, and then it changes based on sun angle. I used Light Mix to isolate Corona Sky from the Sun.
Title: Re: dubcats secret little hideout
Post by: johnymrazko on 2018-07-25, 22:41:54
Thanks , one more question - how do you isolate sun from hdri? Output node creates a mask and then Corona mix map with black color where the sun is and sky map for the rest?

Or painting in photoshop?
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-07-25, 23:40:45
Thanks , one more question - how do you isolate sun from hdri? Output node creates a mask and then Corona mix map with black color where the sun is and sky map for the rest?

Or painting in photoshop?

Photoshop does not have 32bit floating point support, so if you open a HDRi in Photoshop and resave, it is basically ruined.

If you only have Photoshop, you can create a white mask where the sun is, and load it in 3dsMax as gamma 1.0
There are different methods you can split and add them together again, here is one example.

(https://i.imgur.com/m2Cp2DN.jpg)

Affinity Photo has 32bit floating point support. So you can remove or isolate the sun inside the program.
Title: Re: dubcats secret little hideout
Post by: johnymrazko on 2018-07-26, 08:16:24
Are you using native 3ds max maps for a reason? would this work with Corona Mix and Corona Bitmap in the same way? when creating mask in photoshop, can I just add a new layer on the hdri and create mask? then is it correct to convert to 8bit and save as jpg? and then load into max with 1.0 gamma? In your last screenshot you showed that it is possible to avoid Corona Sun completely and use only masked sun to create direct light right? that 9999 rgb x 37 rgb is based on Corona Sun + Sky setup? matching 117 RGB value?

Also when using that hdri in real world scenario can I adjust exposure in framebuffer to my liking?

And how do you decide how large should the sun circle be? Do you include flares or only the sun disk?

Sorry for a lot of questions but I am trying to understand this to make it work correctly
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-07-26, 19:28:39
Hey!

Quote from: johnymrazko
Are you using native 3ds max maps for a reason? would this work with Corona Mix and Corona Bitmap in the same way?
You could use CoronaMix and disable "Perform mixing in sRGB space".
I usually drag and drop bitmaps into slate, and then run Corona Converter to convert them to Corona Bitmap.

Quote from: johnymrazko
when creating mask in photoshop, can I just add a new layer on the hdri and create mask? then is it correct to convert to 8bit and save as jpg? and then load into max with 1.0 gamma?
Yes to everything.

Quote from: johnymrazko
In your last screenshot you showed that it is possible to avoid Corona Sun completely and use only masked sun to create direct light right? that 9999 rgb x 37 rgb is based on Corona Sun + Sky setup? matching 117 RGB value?
Yes. I calibrated the HDRi sun to match isolated Corona Sun. Both will produce the exact same result.

Quote from: johnymrazko
Also when using that hdri in real world scenario can I adjust exposure in framebuffer to my liking?
True albedo matching is only necessary when we want to calibrate light and materials to real world values. When it's calibrated, you can use whatever you want to set  the mood.
If online stores could spend 1min extra when shooting HDRis, and just take a few pictures of a Color Checker or a 18% grey sphere. We could calibrate our HDRis to the actual capture.

Quote from: johnymrazko
And how do you decide how large should the sun circle be? Do you include flares or only the sun disk?
In this case I looked up at the NoEmotion sun. Moved a Corona Sun until it was in the middle of the NoEmotion sun, because the NoEmotion sun was huge.
Then I placed a standard camera at 0,0,0 facing south (south is the standard HDRi direction, the sun will show up in the center). Threw on a CoronaCameraMod, and enabled Projection type "Spherical". Then I changed the render resolution to match the HDRi and made a HDRi of Corona Sun. This is my mask.

When it comes to sun size, I guess it depends on what look you are going for. Sun size will not increase the light intensity of the sun, it will only make the shadows softer.
Most HDRi captures have a sun size of 2.
Title: Re: dubcats secret little hideout
Post by: Jpjapers on 2018-07-27, 22:00:42
Honestly, how do you know all this stuff?
Its fascinating to follow this thread. What is your background?
Title: Re: dubcats secret little hideout
Post by: sprayer on 2018-07-27, 23:23:13
Photoshop does not have 32bit floating point support, so if you open a HDRi in Photoshop and resave, it is basically ruined.
from adobe page
Quote
In Photoshop, the luminance values of an HDR image are stored using a floating-point numeric representation that’s 32 bits long (32‑bits-per-channel). The luminance values in an HDR image are directly related to the amount of light in a scene.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-07-28, 00:54:33
What is your background?
Half Life 1 modder turned Archviz / BIM :)
My first introduction to 3dsMax was Autodesk Gmax, because Milkshape 3D was lacking a lot of features.

from adobe page
Quote
In Photoshop, the luminance values of an HDR image are stored using a floating-point numeric representation that’s 32 bits long (32‑bits-per-channel). The luminance values in an HDR image are directly related to the amount of light in a scene.

I've posted examples all over the forums for years, but I guess it's best I recap everything here.

I'm running the latest version.

(https://i.imgur.com/ICyhJtr.jpg)

#1
If you go back a few pages and download my ACES tonemapper script for Photoshop. You will notice that bright lights becomes black pixels. This is because Photoshop does not calculate negative values.
The script will split your render into two images and then divide those images together. Photoshop does not handle negative math well, and will return black pixels.

#2

Corona Sun

(https://i.imgur.com/ysrpjvJ.jpg)

Corona Sun rendered as HDRi and re-saved in Photoshop as EXR.
Goodbye values.

(https://i.imgur.com/Mps9YOw.jpg)

Corona Sun rendered as HDRi and re-saved in Photoshop as HDR.
Better than EXR, still not what we expect.

(https://i.imgur.com/9SYxpai.jpg)

#3

32bit floating point displacement.

Proper 32bit map rendered in Corona

(https://i.imgur.com/BicgHVr.jpg)

Re-saved in Photoshop as EXR.
Since this map does not exceed 20 Photoshop Intensity, it will not clip.
Negative values work as intended also.

(https://i.imgur.com/6kmkmvX.jpg)

Re-saved in Photoshop as HDR.
Since this map does not exceed 20 Photoshop Intensity, it will not clip.
But since it's HDR, it will not have negative values.
It also has some weird ass shadow artifacts.

(https://i.imgur.com/10zUDWO.jpg)

So if you use Photoshop you are left with these choices:

EXR: Clamped bright values and clamped negative values.
HDR: Somewhat proper bright values and no negative values.
Internal: Can't do negative math.

I bugged Adobe back in 2016 about this problem. They said they didn't understand what I meant about clipped values above +20 RGB, and asked me to take a print screen of the problem. (I had provided renders like the ones I posted here, but they wanted a print screen of the HDR image) That is when I gave up.
Title: Re: dubcats secret little hideout
Post by: sprayer on 2018-07-28, 08:42:18
I've made some test,
Indeed Photoshop save EXR and HDR in half point, but value is the same. Not sure about negative value, i've test corona sun.
About 20-Photoshop clipping it's just own maths inside Photoshop, but value is fine if you see in other software. For example if you look at corona VFB sun value it's has own value, if you copy VFB to 3ds max VFB it's will have another, so i've check max VFB for re-saved images from photoshop we can load them via 3ds max image viewer. Also i was check in Affinity Photo it's showing the same value as in max VFB and can save EXR in float point by the way.
Also i have check re-saved PSD in Affinity, PSD store also the same value as in max VFB, so the problem goes from Photoshop export module, but PS can work with float point and store all colors but only in PSD file format.  I find at adobe forums what people advice to use some plugins for saving full EXR, i was used EXR loader from arionFX by the way. Native PS EXR loader can't load layers from 3ds max EXR and it seams can't save too
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-08-02, 01:08:43
I dumped the iPhone 10.6 Telephoto Camera just for luls.
It has pretty soft darks and crunchy brights, not bad at all.
"Filmic Highlights" 1 should give you a nice start compared to ACES.

It's still RGB dump, haven't had time to fix my HSL/HSV dumper.
Title: Re: dubcats secret little hideout
Post by: Dionysios.TS on 2018-08-02, 11:07:28
here is a test with the 5ds dump, this is the correct way to use them? may be the higlights are too strong

I did a quick comparison against default ACES.
You have to use "Highlight Compress" 2.5 and "Filmic Highlights" 1 to match default ACES.
So leave "Filmic Highlights" at 1 and adjust "Highlight Compress" from 2.5 to taste.

edit:

I forgot to say that these settings only count for the Canon 5DS dump.

Thanks for your wonderful efforts here!
For the 5DS dump, "Filmic Highlights" at 1, and what about "Filmic Shadows"? I set t at 1 as well but my images are so contrasted, I needed to low down the contrast at 0.65 at least.

Thanks!

Dionysios -
Title: Re: dubcats secret little hideout
Post by: Basshunter on 2018-08-02, 14:28:35
hi @dubcat

couple of questions here:

1) Do your LUTs (Like Canon 5DS .cube file) work in other render engines like V-Ray and FStorm or just Corona?

2) Would you kindly help me understand what ACES is? No matter how hard I try, I can't make sense of it!

Thanks!
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-08-02, 21:15:45
what about "Filmic Shadows"?

Hey!

We use "Filmic Highlights" 1 because it only affects the highlight.
It does not mess with contrast. Here is a little 0-1 RGB dump, the curve continues like that above 1 float.
I can post some log dump examples of different tone mappers when I get time.

(https://i.imgur.com/aeP3QhG.png)

"Filmic Shadows" on the other hand, will only add some wonky contrast to your render.
The camera dump LUTs already contain contrast from the camera. So I would not recommend that you use "Filmic Shadows" in combination with the camera LUTs.

(https://i.imgur.com/pPkSJXa.png)

1) Do your LUTs (Like Canon 5DS .cube file) work in other render engines like V-Ray and FStorm or just Corona?
Hey!

They work in any engine that applies LUTs as sRGB. Corona and VFB+ are the only programs I know that extrapolate values above 1 float.
If you look at the sun and apply a normal LUT in Corona, the sun values are still correct. If you apply the same LUT in Vray, fStorm or Photoshop, the sun value will become 1 float or 255 RGB.


2) Would you kindly help me understand what ACES is? No matter how hard I try, I can't make sense of it!

ACES stands for "Academy Color Encoding System". ACES help unify different encoded material through a prosses called IDT.

But in this thread I'm only talking about the post production tools.
You can see and play around with the tonemapper here

https://www.desmos.com/calculator/h8rbdpawxj

4  Slope        - Controls the overall curvature strength.
7  Toe           - Controls the bottom half of the curve.
11 Shoulder   - Controls the top half of the curve.
8  Black Clip   - Moves the left anchor point below 0.
12 White Clip  - Moves the right anchor point above 1.

and of course the color space:

(https://i.imgur.com/qce4WzN.jpg)

fStorm is the only engine I know that has ACES color space.
Title: Re: dubcats secret little hideout
Post by: Basshunter on 2018-08-02, 21:40:35
fStorm is the only engine I know that has ACES color space.

Is ACES a color space?
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-08-02, 21:51:37
Is ACES a color space?

When your media has gone through the IDT process, it will be converted to ACES color space.
ACES color space is greater than the gamut of the human eye, so it's future proof.
Title: Re: dubcats secret little hideout
Post by: Dionysios.TS on 2018-08-02, 22:10:56
Thanks for getting back and clarifying everything! :)
Title: Re: dubcats secret little hideout
Post by: aldola on 2018-08-03, 04:10:25
hi Dionysios.TS try the 5ds dump with 2.5 highlight compression, its works great
Title: Re: dubcats secret little hideout
Post by: Dionysios.TS on 2018-08-03, 10:26:45
hi Dionysios.TS try the 5ds dump with 2.5 highlight compression, its works great

Thanks! This is what I did but I had some questions and doubts about the contrast.

Thanks again!

Dionysios -
Title: Re: dubcats secret little hideout
Post by: oddvisionary on 2018-08-03, 17:18:56
Would you kindly help me understand what ACES is? No matter how hard I try, I can't make sense of it!

I have a lot of documentation from entry to med-high level if you want. here's some links :


https://www.slideshare.net/hpduiker/acescg-a-common-color-encoding-for-visual-effects-applications

https://acescentral.com/t/what-are-the-advantages-of-using-aces-for-color-correction/49
Title: Re: dubcats secret little hideout
Post by: Basshunter on 2018-08-07, 20:52:14

I have a lot of documentation from entry to med-high level if you want. here's some links :


I'll check them out. Thanks for your time.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-08-08, 00:20:21
Every now and then I get questions about Reflection Level and IOR. I will use this post as a reference.

I associate Reflection Level with Opacity in Photoshop.
Imagine IOR inside a folder in Photoshop. This folder is Reflection Level. Bellow this folder you have a black layer.
The IOR/Black layer will always be 100% opacity. But you can change the Opacity of the Reflection Level folder.

(https://i.imgur.com/SGCuIHm.png)

When Reflection Level is 1, the folder inside Photoshop is 100% Opacity. We get 100% correct IOR values.

(https://i.imgur.com/Lz5LfHt.png)

When Reflection Level is 0, the folder inside Photoshop is 0%. We only see the black layer. 0% IOR values.

(https://i.imgur.com/edx0BZ3.png)

If we change Reflection Level to 0.5, the folder inside Photoshop is 50%. We get 50% IOR and 50% black.

(https://i.imgur.com/LnMedZK.png)

So what is 50% IOR.
First we need to convert the IOR value to Reflectivity.
Let's say our material is IOR 1.5.

Reflectivity = (((1-IOR)/(1+IOR))^2)*100 = 4%

Then we take 4% and multiply it by 0.5 (50%) = 2%

Let's convert it back to IOR.
IOR = 1/((2/(sqrt((Reflectivity/100))+1))-1) = 1.33

So if we use IOR 1.5 and 0.5 Reflection Level, our F0 point will be IOR 1.33 instead of 1.5.
But this is not the problem. The problem is that we also reduce the Fresnel edge by 50%. This edge should be pure white (1 float aka 255 RGB).
50% of 1 is 0.5, the Fresnel edge will be 127.5 RGB instead of 255 RGB. This is where our material is no longer physically plausible.

But since we have done the math, you can just change the IOR to 1.33 and increase Reflection Level to 1. This will give you the same result as IOR 1.5 and 0.5 Reflection Level. Only the material will be physically plausible.

When you buy models online, they usually come with ridiculous values like IOR 1.8 and Reflection Level 0.5.
These are not physically plausible, since Reflection Level is bellow 1.
Let's do some math and see what the actual IOR value is.
IOR 1.8 is 8.16 Reflectivity.
50% of 8.16% is 4.08%.
4.08% is IOR 1.51.
In this case they could just have used IOR 1.5 and Reflection Level 1, and the material would look the same and be physically plausible.

We can't touch Reflection Level, but there are two methods you can use to add imperfections to your reflections. (If we ignore bump/normal/displacement).
You have to ask yourself these two questions:
* Are these imperfections surface imperfections ? In that case you want to use a glossiness map.
* Are these imperfections caused by micro occlusion, small scale shadowing. In that case you want to use a custom IOR map to fake depth.
  Corona could auto generate this IOR map from a normal map, but that is currently not the case. (I will share a Normal to IOR LUT soon, but you have to do a few steps before applying the LUT).

If you have a cross specular scan of your material, it does not hurt to use my roughness to IOR LUT. Real world scans always include micro occlusion that Corona can not generate with glossiness or normal maps.

In Vray Next they have added this tool tip. Maybe Corona should do this too.

(https://i.imgur.com/9N3UNcH.png)

Here are some examples that show how F0 and the Fresnel edge gets clamped when you reduce Reflection Level.
The right square image is an unwrapped version of the sphere, where each vertical line is a degree. And the right image is a render in Corona.

(https://i.imgur.com/YPgBzXB.png)

(https://i.imgur.com/1mHsm0l.png)

(https://i.imgur.com/8FyDLsc.png)

(https://i.imgur.com/INx64tH.png)

(https://i.imgur.com/6ktxug0.png)

(https://i.imgur.com/pRHLDkT.png)

TLDR;
* Leave Reflection Level at 1 for physically plausible materials.
* Use glossiness for surface imperfections.
* Use IOR maps for micro occlusion, small scale shadowing.
Title: Re: dubcats secret little hideout
Post by: aldola on 2018-08-10, 16:36:56
hi dubcat, do you have more dumps to test? i enjoyed the last ones a lot
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-08-11, 12:15:13
do you have more dumps to test?

Hey!

Do you mean camera luts ?
What cameras would you be interested in ?

edit:
If anyone of you have a camera request, let me know and I'll see what I can do :)
Title: Re: dubcats secret little hideout
Post by: siebe on 2018-08-12, 09:56:21
The Canon 5D Mark I (classic) always had something special in the color rendition.
Title: Re: dubcats secret little hideout
Post by: Basshunter on 2018-08-14, 05:50:04
Hey Dubcat.

Can I ask your opinion on something?

What do you think would be the best approach for recreating (Modeling and texturing) a highly detailed photorealistic reclaimed wood table top like this one?

I have no access to the real thing so scanning isn't possible.
Title: Re: dubcats secret little hideout
Post by: aldola on 2018-08-14, 16:07:43
i love hisao suzuki work, but i dont know the camera he used, may be someone here knows it
Title: Re: dubcats secret little hideout
Post by: oddvisionary on 2018-08-14, 16:32:07
Hey Dubcat.

Can I ask your opinion on something?

What do you think would be the best approach for recreating (Modeling and texturing) a highly detailed photorealistic reclaimed wood table top like this one?

I have no access to the real thing so scanning isn't possible.

Zbrush. Seriously, with some wood brush, this is the most efficient way for sculpting/modeling your reference.
Title: Re: dubcats secret little hideout
Post by: Basshunter on 2018-08-14, 20:19:59
Zbrush. Seriously, with some wood brush, this is the most efficient way for sculpting/modeling your reference.

Thanks for your opinion Oddivisionary. I appreciate it.

Can I ask you something else?

once the sculpting is done, how would you approach texturing process?
Title: Re: dubcats secret little hideout
Post by: oddvisionary on 2018-08-15, 00:41:38
Zbrush. Seriously, with some wood brush, this is the most efficient way for sculpting/modeling your reference.

Thanks for your opinion Oddivisionary. I appreciate it.

Can I ask you something else?

once the sculpting is done, how would you approach texturing process?

Pleasure. I'm not a Zbrush specialist but there is two ways :

- Sculpt a non detailed version of the wood, and add the textures using Mari/Substance Painter (including bump or normal or displacement) : this way you have a bit more freedom in the texturing processs. You can use photo scanned seamless textures as well as a starting point.
- Texture directly from Zbrush as I've seen some incredible texturing done with it.
Title: Re: dubcats secret little hideout
Post by: johnymrazko on 2018-08-21, 07:50:37
Hi dubcat, I got into hdri calibration thanks to your tips thank you! However I would like to somehow calibrate hdri that has partially overcast sun - is that possible in any way? or is it just eyeballing then? for example some of noemotion evening hdris so that the intensity of direct light would be correct
Title: Re: dubcats secret little hideout
Post by: romullus on 2018-08-21, 11:04:41
And one more question about HDRI from me. I remember you mentioned that photoshop damges HDRI files uppon saving them. How would be possible to check if a file was crippled? I took two files, one with unclipped dynamic range in HDR format and another with clipped range in EXR format, made simple offset adjustment in photoshop and resaved both in their respective formats. Both files came out at almost exact same size (difference is within few bytes), both have unchanged dynamic range and renders identical to unmodified files (except for the shadow position, of course). For me it looks like the files weren't damaged at all and are perfectly safe to use. Am i missing something? I would like to adjust transformation of most of my HDRIs, but before doing that i want to be sure that i won't do any irreversible damage.
Title: Re: dubcats secret little hideout
Post by: Dippndots on 2018-08-22, 13:48:27
@romullus regarding EXR, if you save a "32-bit" EXR from photoshop and try to use it in max, the window that pops up after selecting the file will list each channel as 16-bit, if you have ProEXR, I'm under the impression that it saves correctly?
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-08-23, 21:37:51
The Canon 5D Mark I (classic) always had something special in the color rendition.
Hey!

Here is the RGB version of the LUT. It actually brightens 0 RGB, quite interesting.

Hey Dubcat.

Hey man!
I see oddvisionary has been kind enough to answer when I was afk. I would use your sculpting software of choice and Painter.
I would also generate an IOR map from the normal map, since this model would be fictional and not based on specular scans.
You need the IOR map for micro shadowing like here:

(https://i.imgur.com/P3oQX38.jpg)

Hi dubcat, I got into hdri calibration thanks to your tips thank you! However I would like to somehow calibrate hdri that has partially overcast sun - is that possible in any way? or is it just eyeballing then? for example some of noemotion evening hdris so that the intensity of direct light would be correct

Hey!
If the sun is blocked by clouds and the HDRi provider does not include a grey card reference, we just have to guess. If you give me a link to one of the HDRis you have in mind, I can take a look at it.

If you are interested in getting real world values, you can do this:

- Go outside when it's cloudy.
- Place a ColorChecker grey card on the ground.
- Take a photo of the grey card.
- Recreate the grey color material. If you use a ColorChecker Passport, the grey bellow yellow is 19.8% linear (122 sRGB). (A grey sphere would be best, since you can capture F0).
- Create a camera with the same settings you used on the real camera.
- Calibrate your HDRi until the real and digital color checker match in values.

Before doing that i want to be sure that i won't do any irreversible damage.

Hey man!

(https://i.imgur.com/p30Vmcs.jpg)

(https://i.imgur.com/jZ8lR5Y.jpg)

My guess is that the HDRis you tested already had low sun values, that are bellow Photoshops clip value. If you add 7 +20 Exposures in Photoshop above a 255 RGB layer. You will go above the threshold and it turns black.

(https://i.imgur.com/JY60e5H.jpg)

I've attached the Corona Sun/Sky HDRi saved from Corona, if you want to do tests on that one.

edit: fixed typo, i meant specular not spectacular :p
Title: Re: dubcats secret little hideout
Post by: Basshunter on 2018-08-23, 21:48:16
Thanks for your answer @dubcat
Title: Re: dubcats secret little hideout
Post by: pokoy on 2018-08-23, 22:14:16
Quote
You will go above the threshold and it turns black.

You had one job, Photoshop. Someone should tell Adobe it's 2018 already *facepalm*
Title: Re: dubcats secret little hideout
Post by: siebe on 2018-08-24, 07:21:44
Hey!

Here is the RGB version of the LUT. It actually brightens 0 RGB, quite interesting.


Thanks! you are the best :)
Title: Re: dubcats secret little hideout
Post by: johnymrazko on 2018-08-24, 07:44:37
For example 03-29_Sunset from noemotion if you wouldn´t mind :) thanks a lot

Title: Re: dubcats secret little hideout
Post by: romullus on 2018-08-24, 09:29:40
My guess is that the HDRis you tested already had low sun values, that are bellow Photoshops clip value. If you add 7 +20 Exposures in Photoshop above a 255 RGB layer. You will go above the threshold and it turns black.

Ah, that might be the case indeed. Good news that you can't ruin HDRIs that are already ruined :]
Title: Re: dubcats secret little hideout
Post by: Basshunter on 2018-08-24, 14:25:22
Hey dubcat,

Do you think there's any way to guess the albedo color of an object (In this particular case a wood floor) from just reference photos (Low quality) with different light conditions?
Title: Re: dubcats secret little hideout
Post by: romullus on 2018-08-25, 11:14:45
I would also generate an IOR map from the normal map, since this model would be fictional and not based on specular scans.
You need the IOR map for micro shadowing like here:

Hi dubcat! Would it be too much to ask if you have normals to IOR photoshop action and are willing to share it? I know that you already gave us specular to IOR and roughness to IOR actions, but one of them doesn't work for me and the other one doesn't give as good result as i hoped for (likely because i'm doing something wrong). I have a feeling that normals to IOR might be what doctor prescribed :]
Title: Re: dubcats secret little hideout
Post by: romullus on 2018-08-27, 14:46:49
My guess is that the HDRis you tested already had low sun values, that are bellow Photoshops clip value. If you add 7 +20 Exposures in Photoshop above a 255 RGB layer. You will go above the threshold and it turns black.

So what would be solution to editing/saving of full float EXRs? I have some 8K 32 bit displacement maps that i would like to downsize to 4K and resave, but can't figure out how to do that. Photoshop is no go, my beloved small app Picturenaut is as bad if not worse. I even tried to use 3ds max slate editor's option to render map and save to exr, just to find that it clips everything to 8 bits *sigh

Is there some app that can edit and save 32 bit files in a proper manner? Preferably free or low cost one.
Title: Re: dubcats secret little hideout
Post by: Juraj Talcik on 2018-08-27, 14:53:33
Affinity designer has superior 32bit environment capabilities compared to Photoshop. They really outdid Adobe at this.
Title: Re: dubcats secret little hideout
Post by: romullus on 2018-08-27, 15:19:54
Thanks for the info! Downloading trial now.
Title: Re: dubcats secret little hideout
Post by: burnin on 2018-08-27, 17:09:51
Is there some app that can edit and save 32 bit files in a proper manner? Preferably free or low cost one.
PhotoLine (https://www.pl32.com/index.php) (59 €)
GIMP (https://www.gimp.org/) (FOSS)
Picturenaut (http://www.hdrlabs.com/picturenaut/) HDR maker & tone mapper (FOSS)
Title: Re: dubcats secret little hideout
Post by: romullus on 2018-08-27, 19:48:45
I'm getting odd results here. Even though Affinity exports fully retained dynamic range, the results i'm getting from original and resaved EXR's, are quite significant. But strangest thing, that Affinity's exported displacement map is giving better result than original, i.e. comparing low-poly model renders made with original displacement map and with resaved in Affinity one to high-poly render, then latter is much closer to real thing. What the...? Both textures outside of 3ds max looks pretty much identical, but max treats them differently. So much for care free 32bit displacement rendering... :/

@burnin, thanks i'll look at your links, although i can already dismiss Picturenaut, as it's completely unsuitable for work with full float formats and has almost no editing capabilities. However it is still great as a HDR viewer.
Title: Re: dubcats secret little hideout
Post by: Juraj Talcik on 2018-08-27, 19:52:34
That is very strange, could it have done some interpolation perhaps ? Do you get different result even if you simply open and export it, or do you have to resize to produce the differences.
Title: Re: dubcats secret little hideout
Post by: romullus on 2018-08-27, 20:05:03
My initial reaction too was that it might something to do with interpolation, therefore i did remaining tests with unchanged size - just opened image in Affinity and resaved with different name. Somehow i think it's more 3ds max's fault than Affinity's. Original file is single channel and Affinity save it as RGBA. Resaved file is getting slightly bigger in size (not by much). But strangest things happens inside 3ds max. Max's bitmap loader reports original file as 32bit greyscale, but once loaded in slate editor it has populated all 3 channels with data, however when it loads Affinity's file, it reports it as 32bit RGBA, but in slate editor it has only red channel populated!!! I even tried to change max bitmap to Corona bitmap or even another renderer, but results always is the same, i.e. - different displacement.

I can share a link to that particular asset, if someone is interesting to give a try to this mystery.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-08-28, 20:58:46
For example 03-29_Sunset from noemotion if you wouldn´t mind :) thanks a lot

Hey!

I will have a look at it in the coming days :)

Do you think there's any way to guess the albedo color of an object (In this particular case a wood floor) from just reference photos (Low quality) with different light conditions?

Hey man!

You can compare CGI values to Ohms Law Triangle

(https://i.imgur.com/b8UuGFD.png)

When it comes to Ohms Law, you divide volts with amps and ohms. And multiply Amps and Ohms. If you know two of the values, you can calculate the third value.

(https://i.imgur.com/n9kN2Q0.png)

We don't divide or multiply in my CGI triangle. But if you hold your hand over the unknown value, you can see what values you need to have, to calculate the third value.

I can share a link to that particular asset, if someone is interesting to give a try to this mystery.

Hey!

That would be awesome!
Title: Re: dubcats secret little hideout
Post by: romullus on 2018-08-28, 21:27:57
I can share a link to that particular asset, if someone is interesting to give a try to this mystery.

Hey!

That would be awesome!

Hi dubcat! The link is this: https://www.cgtrader.com/free-3d-models/exterior/landscape/8k-mountain-rock-scan-a  If you don't have cgtrader account and don't want to create one, just let me know and i will send you the files privately.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-08-28, 21:35:13
Hey man!

I have an account, downloading right now. Will have a look at it in the coming days together with Mrazkos HDRi question :)
Title: Re: dubcats secret little hideout
Post by: romullus on 2018-08-28, 22:40:37
Thank you! :]
Title: Re: dubcats secret little hideout
Post by: Basshunter on 2018-09-05, 22:10:28
Hey dubcat,

Is there any chance to have an iPad Air LUT?

I'm needing it for a photomatch. Thanks
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-09-07, 03:49:02
For example 03-29_Sunset from noemotion if you wouldn´t mind :) thanks a lot

Hey!

It's really hard to calibrate these HDRis when you don't have a real world reference. Archviz is really lacking behind when it comes to greycard and chrome sphere "light direction" reference, but one day there will be a store that provide these maps publicly. And it will change everything.

The best thing you can calibrate against is Corona Sun 64 Size at the sun angle, this size will not cover the shadow diffusion. And we know that shadow diffusion is not the same as EV. Since the HDRi source have not given us any real world reference, it is just a guessing game at this point.

Hi dubcat! The link is this: https://www.cgtrader.com/free-3d-models/exterior/landscape/8k-mountain-rock-scan-a

Hey!

I have done a few tests, and it all comes down to bad displacement map.
You can generate a proper map inside zBrush like this:
Go into the "Preferences" tab, and select "Transpose Units". Make sure it's calibrated to 1 scale cm.
Load the low res unwrapped mesh in zBrush, and then load the high res mesh as a sub tool.
Divide the low-res mesh as much as you can for good measure. Select the low res mesh in "Subtool", but deactivate the eye. Activate the eye on the high res mesh, if it's not already activated.
Click on "Project" and increase "Dist" to 1, hit ProjectAll.
Go down to "Displacement Map" and activate 32 bit.
Export the map.

Is there any chance to have an iPad Air LUT?

Hey!

The closet physical thing I can get my hands on is Apple iPad 7.4. I have limited knowledge of Apple, as I'm an Android user. Maybe they have kept the same curve on all their devices. If you are the person capturing the photos on iPhone, I would do a google search on "ipad capture raw" and capture the photos as raw. Most modern phones/pads have raw support, but not officially.
Title: Re: dubcats secret little hideout
Post by: Basshunter on 2018-09-07, 06:43:04
The closet physical thing I can get my hands on is Apple iPad 7.4. I have limited knowledge of Apple, as I'm an Android user. Maybe they have kept the same curve on all their devices. If you are the person capturing the photos on iPhone, I would do a google search on "ipad capture raw" and capture the photos as raw. Most modern phones/pads have raw support, but not officially.

Thank you Dubcat for providing this LUT. What do you mean by iPad "7.4"?

Is it sRGB by the way?

I have and iPad Air 1, so I've been trying to find some information on how to create the LUTs by my self, but haven't found anything useful. I would be very grateful if you could teach me the process.

Once again, thanks for your invaluable help.
Title: Re: dubcats secret little hideout
Post by: romullus on 2018-09-07, 14:31:02
I have done a few tests, and it all comes down to bad displacement map.

That's interesting. I will try to rebake maps with xNormal and see if that helps. Thanks for the help and sorry for bothering you with the issue that i shoud've be able to solve by myself :]
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-09-16, 03:54:44
Thank you Dubcat for providing this LUT. What do you mean by iPad "7.4"?

Is it sRGB by the way?

Hey!

Apple iPad Pro 10.5-Inch from 2017. All the current dumps are sRGB (not log) made to work inside Corona VFB.

sorry for bothering you with the issue that i shoud've be able to solve by myself :]

Hey man, any time. I was curious myself.

---------------------------

I finally have all the materials for my calibrated test room. I will use this scene as a real world example to push Corona features further.

(https://i.imgur.com/owVJPBE.jpg)
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-09-23, 02:49:39
Here's the first puzzle, it's 14 cm in diameter.

edit with some facts:
This is an Ikea ARÖD lamp with a 60W bulb (Keep tuned for a 3D model, and scanned scene).
The HDR is calibrated to real world values.
This 60W lamp is almost 33+, makes you second guess those 16+ HDRIs with a sun.
This HDR dump has never touched Photoshop.

This initial scan already give us a lot of camera bloom information.

This is how the original capture look at 22 fstop, 30 sec exposure, 100 ISO.

(https://i.imgur.com/bEazcpL.jpg)

Hit 8 in 3dsMax "Environment and Effects", drag the HDR into "Environment Map", change "Environ Map" inside the bitmap to Screen. Change your Render size to 5184x3456. Go into "Scene" and change your "Pass Limit" to 1. Change your exposure settings to 22 fstop, 30 sec exposure, 100 ISO. Hit render. Go crazy and try to match the real world bloom. The background is black in real life.

(https://i.imgur.com/35bqpnh.png)
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-09-25, 15:01:20
Well I guess that has to be expected as the actual bloom and glare implementations are 2D effects based on pixel intensities. You won't be able to come even close to the ground truth without modeling the lenses and simulating light through it. That said, that's actually a good starting point to modify the effects behaviors in order to fake it better.
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-09-25, 15:55:19
Here is my attempt, adjusted visually in less than 60s. It did come way better than I expected actually. No pixel peeping here, just really quick test. No glare, bloom to 0.6, everything else to default.

(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=91115;image)
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-09-25, 23:23:12
Here is my attempt.

Hey Fluss, thanks for the tests. Really appreciate it!

---------------------------------------------------------------

I've been drained for energy all month, but I really want to get this analysis scene up and running as fast as possible.

A few days ago I generated a custom Linear Camera Profile for Lightroom. Camera Profiles contain 3 main settings, I kept Adobes raw sensor color conversion, but removed the contrast curve.
I wanted to compare my new Lightroom camera profile against DcRaw and Capture One.

I've read a lot of great things about Capture One, so if anyone know why Capture One is so off compared to the others, let me know. Because I would love to use Capture One as my tethering program. Capture One is using the Linear Response Curve setting.

(https://i.imgur.com/Xkb8c7x.jpg)

I loaded my Ikea 60W light dump into Corona, changed to orthographic view, and matched a Corona Light to the actual captured light bulb dimensions.
I matched the Corona Light intensity against the HDR values using "Default: W/(sr.m^2)".
When I changed the light settings to "Lumen (lm)", the intensity was 760 Lumen.
A 60W bulb is rated around 800 Lumen, the bulb I was using has some kind of coating. So these test results are pretty sport on.

(https://i.imgur.com/Hy4xMts.png)

(https://i.imgur.com/H2O6ExE.png)
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-09-26, 00:46:21
I suppose you made a custom DCP profile from lightroom's one by removing the embedded curve with 3D Lut creator. But I guess you were keeping the HSV correction tho. Did you try to make a profile without that HSV inheritance to see how it compares to the capture one pro linear response?
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-09-26, 01:26:52
Did you try to make a profile without that HSV inheritance to see how it compares to the capture one pro linear response?

Hey!

If we disable HSV in Fusion/3D LUT Creator it looks like this, it matches Capture One closer.

(https://i.imgur.com/rWsFQy1.jpg)

Even though the current tests are spot on intensity wise, maybe Capture One or no HSV are more spot on when it comes to colors. I've noticed that the current light temperature looks really greenish. Even though both are loaded as 6500k. Thanks for the head up, will try both on my 18% sphere!
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-09-26, 01:57:13
In your 3 previous tests, luminance seems pretty consistent tho, this one looks a bit off luminance wise. Would be great to see how they compare on that point, in CIE LAB , with proper luminance metric (no RGB, HSL/HSV etc..). If it's consistent across the dumps, i'd bet for tint shifting or white balance.

What command did you use for the dcraw dump (Especially for the color option)?
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-09-28, 01:58:27
What command did you use for the dcraw dump (Especially for the color option)?

Hey!

-v -H 0 -o 1 -q 3 -4 -T

In this specific case, since I shoot all the lights at 6500 (since our CG life is depending on this setting), the exif is already 6500.
So these settings give me the same result

-v -w -H 0 -o 1 -q 3 -4 -T

I haven't had any spare time since last time.
The next thing on my schedule is to 3D scan the analysis scene, and replace the rough scan geo with proper 3D models.
After that I will material scan the rough black fabric that my analysis scene is covered with.
When those two variables are finally taken care off, we can nail the raw image variables.
Everything will be open source as always :)
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-09-28, 02:42:27
Bertrand Benoit aka BBB3viz released an awesome set of images lately, you can check them out at https://bertrand-benoit.com/blog/classical.
People have asked him what wall paint value he used, and he responded 180 RGB.
This answer has then turned into another questing. What does he mean about 180 RGB, does it mean sRGB or does it actually mean RGB.

180 sRGB is 46.5% reflectance and 180 RGB is 70.6%.
So he is talking about real linear RGB values. 70.6% is still dark for white values, but this is the common average value for white paint.

In Scandinavia we have a standard white color for doors, windows etc. And that color is called Eggwhite, you can find it here https://www.e-paint.co.uk/Lab_values.asp?cRange=RAL%20Classic&cRef=RAL%209010&cDescription=Pure%20white (https://www.e-paint.co.uk/Lab_values.asp?cRange=RAL%20Classic&cRef=RAL%209010&cDescription=Pure%20white). This paint is 84%. If we remove 1.5 IOR from the scanned value, we get this albedo value.

(https://i.imgur.com/sz1iDsl.png)

edit:
Made the image 500px wide.
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-09-28, 15:15:55
People have asked him what wall paint value he used, and he responded 180 RGB.
This answer has then turned into another questing. What does he mean about 180 RGB, does it mean sRGB or does it actually mean RGB.

180 sRGB is 46.5% reflectance and 180 RGB is 70.6%.
So he is talking about real linear RGB values. 70.6% is still dark for white values, but this is the common average value for white paint.

Well despite his amazing renders, BB is more of an eyeballing kind of guy (and he has an insane eye), he can can pretty much nail any materials just by looking at them. That leaves me speechless every time! But after reviewing some of his scenes (some older ones, don't know is it still the case), I just noticed he is not using "strict PBR rules". So I guess that's just the expression of his artistic vision. That said, his approach is not devoid of foundation and we can clearly identify some technical background behind all of this. Overall reflectance values of the scene are indeed extremely important as it will greatly influence how light propagates through it and thus affect the dynamic range of the final render. That's just a pain in the ass to get it right for every single material in the scene (for me at least).

I've been lurking around on different forums and articles in that regard. Without a "state of the art" material scanner, it's hard to guess these values. Anyway, Some studios are relying on this sensor: https://www.nixsensor.com/. For sure, it is not as smart as being able to split it into diffuse and spec or anything nice like that but you'll get an accurate overall brightness and hue for your material for cheap. What's more, it can give you ACEScg values (the pro one), so linear data. I'm considering buying one of them atm.

And here we come, talking ACES workflow. I had some time to kill so I decided to give ACES a spin. I used Vray and OCIO config to see what it gets.

lin sRGB + 2.2 gama curve
(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=91266;image)

lin ACEScg + sRGB viewtransform
(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=91268;image)

lin sRGB +5EV + 2.2 gama curve
(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=91270;image)

lin ACEScg +5EV + sRGB viewtransform
(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=91272;image)

We can clearly see the advantages of the ACES tone mapping. The way blown highlights are handled is way closer to what a real camera would produce. We can feel the "Fstorm look" there uh? The only drawback is that "ACES bug" with bright saturated values professor Dubcat was referring earlier this topic. At this point, I'm not that sure it is a bug rather than a "workflow issue".

That color 'bug" literally freaked me out! Why the fuck is this happening? So I tried to figure out what was the issue and here what I found :

To understand that we need to be pragmatical.

The issue: I'm increasing EVs and my primaries are not fading to white in sRGB. It does in ACES but colors seem shifted. Why?

According to the definition of EV (Wikipedia), the Exposure value is used to indicate an interval on the photographic exposure scale, with a difference of 1 EV corresponding to a standard power-of-2 exposure step, commonly referred to as a stop. So basically, it's a multiply operation. The colors used for the lights are pure sRGB primaries (1,0,0 ; 0,1,0 ; 0,0,1). I guess you understand what's happening at this point. Let's sample our blue: At current exposure value we have (0,0,3.391 float 32). So multiply that by whatever you want to, you'll always see a blue primary (the blue being clipped to be displayed and the other two components being 0 -> REMINDER: 0*x=0 😉).

Now let's change that blue color to (0.1,0.1,1)

sRGB - start to see fading even at current exposure
(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=91274;image)

sRGB +5EV - totally faded to white while the other two primaries remain the same.
(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=91276;image)

OK, that's just math so shouldn't ACES behave the same way as we were using the same pure primaries? In fact, it does...

What's defining a color ? Well it's a balance between R, G and B values (thanks captain obvious). What I mean here is that your color won't be more blue by increasing the blue component (that's actually luminance), it will be more blue by removing more red and green.

ACEScg gamut is wider than sRGB gamut which means colors can be more saturated.
(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=91278;image)

So when we are using ACEScg to grade, we are converting from lin sRGB to lin ACEScg. Since the gamut is expanded, my sRGB(0,0,1) is not translated to ACEScg(0,0,1) as it's less saturated. Less saturation brings back a bit of red green to my color in ACEScg colorspace ! and that's why colors fade out! If you try to grade a pure blue primary in ACEScg, it will behave the same way as in sRGB, 100% saturation is reached, 0 red and 0 green, blue is clipped -> no fade out.

But we are actually converting to ACEScg after rendering which introduce some bias in the solution and it is especially visible near extreme values. To avoid that it's better to convert anything that contributes to the color information in the final rendering. So basically all lights and textures that are not supposed to be shades of gray.

(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=91280;image)

(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=91282;image)

Title: Re: dubcats secret little hideout
Post by: Juraj Talcik on 2018-09-28, 15:27:55
Never heard of the NIX scanner, that is cool nifty toy :- ). I knew I could somehow use xRite sond to do this but never bothered.

I wonder how far are these from "diffuse albedo" to be used in our generic shader. Aren't these still perceptive colors ?

Now only which one to buy..
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-09-28, 16:27:58
Never heard of the NIX scanner, that is cool nifty toy :- ). I knew I could somehow use xRite sond to do this but never bothered.

I wonder how far are these from "diffuse albedo" to be used in our generic shader. Aren't these still perceptive colors ?

Now only which one to buy..

I wonder too... That's why I'm considering buying one but haven't done yet.  What do you mean by perceptive color?

All I know is that it seems pretty accurate (lots of people use that for print matches). I also like the fact that you get control over the illuminant.
(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=91307;image)
Title: Re: dubcats secret little hideout
Post by: karnak on 2018-09-28, 16:32:22
I don't know much about these Nix products (first time I hear of them), but I have been using an X-Rite ColorMunki Photo to get diffuse values.

The ColorMunki Photo is a spectrophotometer that can sample the light spectrum from 380 to 730 nm every 10 nm (or every 3.33 nm in high-resolution mode).
In very simple terms, with the spectral data, you can get RGB values in a color space of your choosing (with appropriate illuminant, primaries and so on).

In my opinion, the data you get from this instrument is good enough, especially considering the price and the size of the device.
I say 'good enough' because the light spectrum is infinite, and with this tool, perhaps we are sampling the bare minimum visible range (380-730 nm) at the bare minimum interval (every 10 nm). I have read a lot of o literature on the subject, and this might lead to slightly inaccurate values in some cases. I feel I have already gone overboard with unrequested details, sorry. :)
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-09-28, 16:41:00
reading some amazon reviews :

"Accuracy and correlation tested with macbeth chart and X-Rite spectroreflectometer.
Very accurate inside sRGB gamut, could be improved a bit in very blue colors.
But it's acceptable for this price and such small trichrometer sensor.
Lovely product. Looking for next product already!"

Good enough for me.
Title: Re: dubcats secret little hideout
Post by: Juraj Talcik on 2018-09-28, 16:50:29
Yeah sounds great, esp. since it comes with simple mobile app.

By perceptive I mean the results (and same goes for all the RAL, NCS, Pantone, etc.. libraries) are supposed to mimic how we perceive these materials by eye under regular daylight.
It was setup fully independent of the concept of diffuse albedo. I am not even sure if they can be considered to be full albedo so that we could just take away some brightness and add some saturation.

These colors always feel like they are too bright to be used in CGI shader.
Title: Re: dubcats secret little hideout
Post by: karnak on 2018-09-28, 18:52:24
I'm not sure about the libraries, but in my previous example what I get from the instrument is the energy that the surface reflects, without distinction between diffuse reflection and specular reflection. Therefore to get only the diffuse you need to subtract the specular reflection and you can do this easily if you know the IOR of the surface (and if you don't care that much about it, you can just remove 4% which is equal to the energy that the default IOR adds).

I think a good way to remove 4% from RGB colors might be to use Lab mode and only work with the L component.
Title: Re: dubcats secret little hideout
Post by: Juraj Talcik on 2018-09-28, 19:15:38
I know about the 0° specular removal, I mentioned that idea multiple times over many years here. But I still have hitch for it to be more complex than just that and my issue is with how the shader uses this data. I know that it is energy conserving and nada,nada.. but it still doesn't end up looking fully right to me.

I've been overthinking this for way too long though..  but I would still like to have physical sample of something that was also scanned by actual BSDF scanner like xRite TAC7 or the ChaosGroup's scanner.
Title: Re: dubcats secret little hideout
Post by: karnak on 2018-09-28, 19:41:55
That would be extremely cool to have.
What X-Rite device you have? I can help you on the software side if you want to read some surfaces.
I know it's not the same as BSDF scanners, but at least it's something.

edit.

I forgot to say that I get the same values with calibrated polarised photography and with spectrophotometer with manual removed specular.

What happens outside F0 is a totally different matter though and depends on other factors, some of them are well approximated by the BRDF models used inside the shader, others are not.
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-10-01, 13:16:46
I forgot to say that I get the same values with calibrated polarised photography and with spectrophotometer with manual removed specular.

What happens outside F0 is a totally different matter though and depends on other factors, some of them are well approximated by the BRDF models used inside the shader, others are not.

Absolutely. Following the energy conservation law, the close relationship between the diffuse and the specular part is what defines the object appearance. When the specularity increases, the diffuse component drops, and vice versa. And that has to be correlated to the micro surface topology itself. These tiny details are what really defines how a surface looks at a defined angle. I guess BSDFs provided by high-end material scanners sort of translate that surface topology information into a fresnel curve across the whole range of angles (sampled x steps, interpolated in between) for both diffuse and specular components. Microfacets models we are using are way too generic in that regards and have a hard time simulating materials with complex microsurface details (wood, fabric etc) but anyway, good enough to achieve pretty decent results most of the time. That said, I'm always wondering why we're stuck with that good old Lambertian diffuse model in corona while almost any other renderers on the market are offering more advanced one.

I miss a macro lens... I'd really like to see how far we can go by scanning small patches of geometry and then making them tillable in order to use them as source pattern in Fstorm Geopattern.
Title: Re: dubcats secret little hideout
Post by: Juraj Talcik on 2018-10-01, 13:50:19
That said, I'm always wondering why we're stuck with that good old Lambertian diffuse model in corona while almost any other renderers on the market are offering more advanced one.

I keep asking Corona devs about this every three months for past three years. If we could at least get option for some existing alternative to soften up look I would be super grateful but Corona shader is super limited and not evolving in any way.

It desperately needs better diffuse shading, Coating, Sheen, etc..

Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-10-01, 16:55:09
Some samples coming from the mura scanner are available at the bottom of the home page :

https://www.muravision.com/
Title: Re: dubcats secret little hideout
Post by: Juraj Talcik on 2018-10-01, 17:27:07
So who asked them for quote :- ) ? I wonder where it stands compered to much more advanced Tac7.

I really need to finish my own, it's sitting sadly half-finished against the wall for past year and half...
Title: Re: dubcats secret little hideout
Post by: Jpjapers on 2018-10-01, 21:07:57
That said, I'm always wondering why we're stuck with that good old Lambertian diffuse model in corona while almost any other renderers on the market are offering more advanced one.

I keep asking Corona devs about this every three months for past three years. If we could at least get option for some existing alternative to soften up look I would be super grateful but Corona shader is super limited and not evolving in any way.

It desperately needs better diffuse shading, Coating, Sheen, etc..

It would be great to have a much more powerful shader I agree completely.

Also has there ever been a thread explaining ACES and why its better?
Title: Re: dubcats secret little hideout
Post by: HVB on 2018-10-02, 09:02:00
So who asked them for quote :- ) ? I wonder where it stands compered to much more advanced Tac7.

I really need to finish my own, it's sitting sadly half-finished against the wall for past year and half...

I asked them a while ago what a Mura desktop scanner cost. And they go for $75k. So not really something for most of us.
Title: Re: dubcats secret little hideout
Post by: piotrus3333 on 2018-10-02, 11:03:55
Also has there ever been a thread explaining ACES and why its better?
aces’ purpose is to help film industry to manage their color input. imagine the number of image capture hardware used, all with different ways of representing captured scenes. than try matching footage from 5d, iphone, red dragon and vfx on top of it. aces makes it easy.
we have it easy from start - most renderers that we use output basicaly the same stuff: hdr color defined by rgb primaries, usualy in a form of half float exr.
long time ago Vlado posted on chaos group forums regarding rendering in aces colorspace. and if I remember correctly you should be able to switch to aces in VRayNext. not sure if it’s there yet though.
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-10-02, 14:06:29
aces’ purpose is to help film industry to manage their color input. imagine the number of image capture hardware used, all with different ways of representing captured scenes. than try matching footage from 5d, iphone, red dragon and vfx on top of it. aces makes it easy.

That's true but only one side of the coin. As it's a scene referred workflow, it also allows you to preserve the whole dynamic range of your data all along the pipeline. What's more, the way RRT/ODT handles colorspace conversion gives results way closer to a film response. That's what really matters for us. You should watch this video which shows convincing results :

we have it easy from start - most renderers that we use output basicaly the same stuff: hdr color defined by rgb sRGB primaries, usualy in a form of half float exr.
long time ago Vlado posted on chaos group forums regarding rendering in aces colorspace. and if I remember correctly you should be able to switch to aces in VRayNext. not sure if it’s there yet though.

For a proper ACEScg workflow, you need to pre-convert your color textures and lights to ACEScg colorspace(D60 illuminant). The only issue is that most renderers rely on the 3D software color management which is, most of the time, based on sRGB color space (D65 illuminant). As far as I know, only maya is color managed atm.

Vray next allows you to convert your textures and colors on the fly with an OCIO node. From what I understand, it does not needs any internal changes for the renderer to handle ACEScg data. Indeed, ACES is a linear-encoded color space and as far as you feed the renderer (performing linear operations) with linear data and as far as you're outputting these linear data in a linear file format (exr), everything should work as intended and you should be able to work in ACEScg in your comp software. Renderers should be color space agnostic in that way. But we are not able to convert anything related to color temperatures  (sun, skies, lights set by illuminant etc..). That's the only blocker I can see. So if we avoid using these components, I guess we should be able to work in ACEScg with corona (assuming we pre-converted all the color textures to ACEScg). Vlado said he is actually working on native ACEScg support in Vray but I have not seen anything out for now.

Disclaimer: Everything discussed here is based on MY interpretation/comprehension of the phenomenon involved and might present some inaccuracies or wrong statements.
Title: Re: dubcats secret little hideout
Post by: piotrus3333 on 2018-10-02, 15:07:04
What's more, the way RRT/ODT handles colorspace conversion gives results way closer to a film response.

aces will not tonemap scene referred image. you will still need to transform it for the display device.
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-10-02, 15:50:48
aces will not tonemap scene referred image.

That's what RRT is meant for.

you will still need to transform it for the display device.

That's what ODT is meant for.

What do you mean?
Title: Re: dubcats secret little hideout
Post by: piotrus3333 on 2018-10-02, 16:06:03
I just dont see aces space as something better for rendering purpose. I was expressing my opinion as an answer to “why is it better?” question few posts ago.
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-10-02, 16:29:34
I just dont see aces space as something better for rendering purpose. I was expressing my opinion as an answer to “why is it better?” question few posts ago.

No problem with that, everybody has is own opinion :-). But I'd be glad to hear some arguments then!
Title: Re: dubcats secret little hideout
Post by: piotrus3333 on 2018-10-02, 17:30:49
assumption1: we put our textures and lights through aces transform. all that goes to non spectral renderer that sees just different numbers (aces primaries). math of light transport is the same in both cases. output is another bunch of numbers that describe scene referred color data. transform it again so it looks good an 8 bit display. since all that started with data described by limits of rgb representation nothing new will appear here.

assumption2: since aces is wide gamut color space it can do more than any rgb space. so you can provide the rendering engine with more data if you can somehow capture it.

thats just my take on the thing. input data limit the output no matter how crazy the math in between.
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-10-02, 19:51:27
assumption 1: Even if it does not make a huge difference, it has been proven that rendering in ACEScg (which is more or less similar to REC.2020) will be closer to a ground truth full spectral rendering. Anders Langland discuss the subject in this article: https://www.colour-science.org/anders-langlands/

assumption 2: just to clarify, ACES color spaces are based on the RGB color-additive model (i.e colors are encoded with R,G and B chromaticities). RGB is a color model like XYZ, HSV, LaB etc.. By RGB, you mean sRGB which is a color space. Btw, you're absolutely not limiting the output by inputting converted data from a smaller gamut color space. As the gamut is smaller, you'll have a smaller subset of possible colors, resulting in a loss of color accuracy for representing the real world data. But you're not limiting anything here.
Title: Re: dubcats secret little hideout
Post by: IsmaeL on 2018-10-03, 12:19:37
Interesting stuff here as always.

About the howl ACES debate, is there any significant advantage we would get from using ACES. This all sounds very complicated and yet I don't really se a big change.

To be honest, I would much rather prefer a wider color space inside of Max. Getting a color managed 3d application like Maya or Blender, I think even Cinema is color managed (not sure).
This would help when inputting real life colors and if we are talking about REC 2020, we could use that color space directly to work in and output images.

The second question is about the ACES compression dubcat uses, I know I read an article years ago about it. Is it somehow related to the ACEScg workflow?? Can we use it independent?? And why should we use it at all?

Finally, what is up with Lambert model for diffuse?? What is Vray using? And how would a different model be better??

BTW. Love that Canon EOS LUT
Title: Re: dubcats secret little hideout
Post by: Juraj Talcik on 2018-10-03, 13:03:45
One idea behind asking for ACES was that it would be one fly swatted together to get both color management and some VFX utility. (And easy way to use their nice filmic tonemapper in correct way).

Corona is already using wide-gamut for internal computation but both input and output are limited to sRGB and yet unmanaged.
3dsMax is not getting color management any soon it seems (unlike Maya), so at least Corona should step up.

Vray uses Lambert by default but gives you option to mix it with Oren-Nayar (it's hidden behind the "diffuse roughness" setting). Issue with lambert is that nothing really looks like it and it's not flexible to adjust in any way (unlike other models).
Simulating rough paint for example with CoronaMTL is currently done by the fresnel mixing GGX specular over Lambert diffuse. It doesn't mesh, it's not giving correct life-like result.
Title: Re: dubcats secret little hideout
Post by: IsmaeL on 2018-10-03, 15:54:20
Thanks Juraj, that clears things up.

So most of this could be resolved by getting a new VFB inside Corona.
One that does correct Filmic tonemapping and where you could preview an image in a certain color space.

Basically what you can already do in Vray when you load the ICC profile of your monitor.

As for Max, you have to request the color management and maybe we get lucky. Here is the link https://forums.autodesk.com/t5/3ds-max-ideas/implement-color-management-in-3ds-max-support-for-icc-luts-etc/idi-p/6790724

As for Lambert, I guess you should just stick to shiny surfaces XD
Title: Re: dubcats secret little hideout
Post by: Basshunter on 2018-10-03, 16:33:05
As it's a scene referred workflow, it also allows you to preserve the whole dynamic range of your data all along the pipeline.

Would you mind to further explain the sentences "it's scene referred workflow" and "it allows to preserve the whole dynamic range of your data all along the pipeline"?
I have troubles understanding some technical expressions in English.
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-10-03, 17:14:34
As it's a scene referred workflow, it also allows you to preserve the whole dynamic range of your data all along the pipeline.

Would you mind to further explain the sentences "it's scene referred workflow" and "it allows to preserve the whole dynamic range of your data all along the pipeline"?
I have troubles understanding some technical expressions in English.

You should look at this article which explains the core fundamentals of the ACES workflow in a quick and efficient way: http://shootdatapost.com/blog/2014/5/16/aces-in-10-minutes
Title: Re: dubcats secret little hideout
Post by: Basshunter on 2018-10-03, 17:16:39
@Fluss. I'll check it out. Thanks
Title: Re: dubcats secret little hideout
Post by: aldola on 2018-10-17, 19:52:21
Hi Dubcat, do you know some way to convert srgb images to LOG32?, i need to use some lut´s in this format
Title: Re: dubcats secret little hideout
Post by: dubcat on 2018-10-28, 05:53:08
Hey!

I've blocked a few web sites this month so I don't have an excuse to procrastinate. I haven't read through the pages since my last post. I see the last post has a question for me. I just want you guys to know that I'm not ignoring you. I will respond when my "official" block is over. I just had to make this post on my phone.

I've been pushing for linear display value for "Value" since Corona Color Picker got introduced. Every time I talk to the Corona team, it seems that this request gets confused with something else, and I honestly don't understand what they confuse it for. I see the RC is almost ready and it results in me clenching to my pillow at night, crying inside.

Every studio/person out there that deal with real world reflectance values, knows that we need linear display for "Value".

This long time "bug" / feature request has now turned into a meme

(https://i.imgur.com/qELyIru.png)

This is the best way I can describe the current problem.

(https://i.imgur.com/oFRWnFB.png)

If you have to deal with real world paint values and scanned values, please let your voice be heard so we can get this quality of life feature implemented.
Title: Re: dubcats secret little hideout
Post by: romullus on 2018-10-28, 08:48:02
I don't work with real world paint and scanned values, but i never understand why CCP shows value in sRGB only. I think it should respect sRGB switcher and show its values accordingly, just like red, green and blue channels does.
Title: Re: dubcats secret little hideout
Post by: Juraj Talcik on 2018-10-28, 13:34:47
Yup, this should be super easy and obvious fix. It's already working on RGB channels, so why not the value ? It absolutely needs to be consistent.
Title: Re: dubcats secret little hideout
Post by: IsmaeL on 2018-10-29, 09:32:26
Definitely annoying. Seams kind of silly that this hasn't been fixed yet.

So where should we post about this, is it a bug or should we go to the feature request??
So many threads around here.
Title: Re: dubcats secret little hideout
Post by: Juraj Talcik on 2018-10-29, 11:26:12
I don't know myself, there isn't clear feedback anywhere. Ideally both.
Title: Re: dubcats secret little hideout
Post by: Jpjapers on 2018-10-29, 12:56:38
I don't know myself, there isn't clear feedback anywhere. Ideally both.

Perhapt there should be a stickied SAT Thread (Small annoying things)
Title: Re: dubcats secret little hideout
Post by: IsmaeL on 2018-10-30, 09:36:56
Perhapt there should be a stickied SAT Thread (Small annoying things)

That is a very good idea
Title: Re: dubcats secret little hideout
Post by: maru on 2018-11-02, 12:35:06
It seems that there is a kind of communication problem between the users requesting this feature, and the developers. We'll be sure to sort this out.
On the other hand, there are some strong arguments why this should not be implemented (or at least not in a way users seem to be expecting it). I do not want to sound too mysterious, but we will have to come up with a clear explanation, and only then share it.
Sorry that this is taking so long.
Title: Re: dubcats secret little hideout
Post by: oddvisionary on 2018-11-02, 17:21:25
Now I know why I got confused by this what seems to be a bug? sRGB/Linear RGB values not showing the correct value. Make sense.
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-11-02, 19:14:16
It seems that there is a kind of communication problem between the users requesting this feature, and the developers. We'll be sure to sort this out.
On the other hand, there are some strong arguments why this should not be implemented (or at least not in a way users seem to be expecting it). I do not want to sound too mysterious, but we will have to come up with a clear explanation, and only then share it.
Sorry that this is taking so long.

Half off-topic : would be nice to have a way to export true RAW linear renders with Corona. Bypassing the internal Corona tonemapping. It seems impossible to have a pure RAW Render. Not bad actually, it will always look more photo real, but it's nice to have something as neutral as possible to sometimes do it all in post for VFX workflow (as it is with Arnold for exemple, which has no tonemapping at all but has OCIO/Lut support).

Octane has a beautiful tonemapping, but there is a checkbox to render without it for neutral linear raw EXR.

Actually, you can. Just leave parameters to default and save it as exr 16 or 32 bits float.
Title: Re: dubcats secret little hideout
Post by: oddvisionary on 2018-11-02, 20:25:58
nevermind
Title: Re: dubcats secret little hideout
Post by: PROH on 2018-11-02, 21:27:25
1 - There is a checkbox in VFB
2 - There is a Beaty RE with a checkbox

Do you need more checkboxes?
Title: Re: dubcats secret little hideout
Post by: oddvisionary on 2018-11-03, 00:23:43
1 - There is a checkbox in VFB
2 - There is a Beaty RE with a checkbox

Do you need more checkboxes?

I just saw tonemapping will be reworked (roadmap). I did not explained myself correctly. IMO UI can be simpler, more organized, less spread. And more transparency regarding the tonemapping would be nice.
Title: Re: dubcats secret little hideout
Post by: Juraj Talcik on 2018-11-04, 14:37:18
I'm as confused as dubcat sometimes...

Dubcat for sure as hell isn't confused lol, what are you on about with the past five or so posts :- D.

Tonemapping will be reworked by offering more advanced algorithm behind it. The UI is already as transparent as it will get, the checkboxes for everything are there.

Title: Re: dubcats secret little hideout
Post by: oddvisionary on 2018-11-04, 16:44:14
I meant : dubcat doesn't have all the answers yet. He is still figurring some stuff out as I am myself. Maybe confused wasn't the correct term here.

There is hidden informations that he has no access to as well. Anyway. 
Title: Re: dubcats secret little hideout
Post by: mh on 2018-11-12, 04:41:53
Here's the first public "Roughness to IOR" LUT test.

Since slate and LUTs are a complete gamma mess, I have embedded all the gamma conversion stuff inside the LUT.


Hi dubcat

This is great! I've been playing with this for the past couple of days and the IOR map works flawlessly! The added detail is astounding

I just want to clarify what the LUT actually does, and what IOR it produces, ie is it true that the high pass filter + LUT results in about 1.52 IOR? This seems fine for most materials but I tend to go a bit lower for plants, is there a nice way how to get the IOR down to say 1.4 and be somewhat precise about it? I could artificially color correct the node to bring the brightness down a bit but it seems contradictory to the whole setup

thanks!
Title: Re: dubcats secret little hideout
Post by: nkilar on 2018-11-15, 08:09:16
Here is a pretty good example of the ACES inspired tonemapping that I think Dubcat was talking about a few pages ago when he compared how F-Storm does things and how Corona does things ->


Maybe its helpful for someone in order to understand the differences :)

I was always under the impression that Octane / F-Storm use spectral rendering (basically converting RGB values to wavelengths internally) and that is what causes the colors to shift when they are bright / have high exposure. @Dubcat Do you have any idea whether those engines still do something differently internally or is it just a tonemapping technique?
Title: Re: dubcats secret little hideout
Post by: oddvisionary on 2018-11-15, 11:15:50
Here is a pretty good example of the ACES

I even requested OCIO in Corona just after I tested it in Arnold. https://corona-renderer.com/forum/index.php?topic=18169
Title: Re: dubcats secret little hideout
Post by: Fluss on 2018-11-15, 12:32:16
I was always under the impression that Octane / F-Storm use spectral rendering (basically converting RGB values to wavelengths internally) and that is what causes the colors to shift when they are bright / have high exposure. @Dubcat Do you have any idea whether those engines still do something differently internally or is it just a tonemapping technique?

I'm pretty convinced that Fstorm/Octane does not use spectral rendering except for specific tasks like dispersion (which is the same for Corona I guess). Spectral rendering tend to produce colored noise which is not the case. I might be wrong tho.

Anyway, the highlight color shift is not related to light transport. It's just a tonemapping technique. Basically, standard sRGB display transform clip colors above 1 resulting in white color. ACES compress values by applying a curve before display adaptation. That's all it takes. I've made some test in Vray via OCIO and it works as intended.
Title: Re: dubcats secret little hideout
Post by: IsmaeL on 2018-11-16, 09:51:48
The only problem I see with OCIO is that it is only a view transform, so you can't save the image from the VFB with transform applied. This is the annoying way Vray has of doing things.
I guess in Corona you could just save the image as is shown in the VFB or make the OCIO apply internally in some advanced option, so people don't mess with it.

What is clear to me, is that we want ACES tone mapping applied as a standard, just like in UE
Title: Re: dubcats secret little hideout
Post by: nkilar on 2018-11-16, 15:52:19
The only problem I see with OCIO is that it is only a view transform, so you can't save the image from the VFB with transform applied. This is the annoying way Vray has of doing things.
I guess in Corona you could just save the image as is shown in the VFB or make the OCIO apply internally in some advanced option, so people don't mess with it.

What is clear to me, is that we want ACES tone mapping applied as a standard, just like in UE

Pretty much +1 on everything you said. The way V-Ray does things is still beyond my understanding. They offer "basic" VFB settings yet you can't even get a LUT saved out of the VFB (at least in certain cases). Why, oh why :)

@Fluss
Yeah, well I was under the impression that because they do some sort of spectral / hybrid rendering that the RGB values get converted to wavelenghts internally and so it gets that ACES OCIO effect going. I hear what you are saying though, would be interesting to dive deeper into it...
Title: Re: dubcats secret little hideout
Post by: DanNissn on 2018-12-28, 05:58:55
@dubcat

Hey I saw your post on the importance of keeping reflection color pure white and understand the importance for keeping the Fresnel edge to pure white. Instead of using IOR maps to add this detail could you still use maps in the reflection slot remapped with a falloff map to upkeep the pure white edge?? Sorry if its a dumb question have been keeping up with all your posts for a while, love all the information and theories/ideas you provide, keep it up
Title: Re: dubcats secret little hideout
Post by: Jpjapers on 2019-01-08, 13:59:34
Im trying to move my workplace onto an ACES workflow and i was wondering if anyone can explain if theres anything that im supposed to be doing with textures?

Also @Dubcat are you still working on the paint LRV LUT? Id be interested to see a step by step tutorial!
Title: Re: dubcats secret little hideout
Post by: dubcat on 2019-01-13, 01:01:45
Hey!
I will be backtracking every post.

is it true that the high pass filter + LUT results in about 1.52 IOR?

Quixel cross specular scan real world materials and generate a roughness map based on their internal system. This result in a less contrasted version of the real specular scan with arbitrary values.
When we high pass a texture, we remove all the arbitrary values and are only left with the contrasting values. These values are universal and will work with any megascans scans. My LUT is calibrated to give you 1.5 IOR when a high passed roughness map should give you 1.5 IOR. If you apply the LUT to an asphalt scan, the base asphalt will give you 1.5 IOR. If there are any gem stones, they will get more IOR, and all the micro shadow areas will get less IOR.
In the future, I hope that render engines will fuse "PBR" and "scanned cross specular" into glossiness. Right now PBR glossiness reduce IOR at lower glossiness values, but it's global and ignore micro shadowing.
My ultimate wish right now would be to get Diffuse Roughness in Corona, and then get some kind of futuristic PBR + scanned cross specular interaction into glossiness for micro shadowing. This would not break the current PBR workflow and/or maps, but only improve them.

I could artificially color correct the node to bring the brightness down a bit but it seems contradictory to the whole setup

This would be 1000 times easier if only Corona had specular support like Unreal 4 and fStorm. We don't have to settle on IOR or Specular, we can have both. I can generate a LUT that has 1.4 IOR as base. But let's cross our fingers that Corona will get a dual setup in the future!

The only problem I see with OCIO is that it is only a view transform, so you can't save the image from the VFB with transform applied. This is the annoying way Vray has of doing things.

THIS! I beta tested this stuff last summer and everything was VFB only, everything got ignored when you saved the image. And the ACES profiles did't have the Epic Unreal 4 blue fixes, so blue turned pink.

Instead of using IOR maps to add this detail could you still use maps in the reflection slot remapped with a falloff map to upkeep the pure white edge?? Sorry if its a dumb question have been keeping up with all your posts for a while, love all the information and theories/ideas you provide, keep it up

I've never though about this situation after PBR glossiness got introduced. But when you think about it, this is something that PBR glossiness should handle. Reflection level reduces everything as Photoshop opacity, so it would reduce everything at the same %. While IOR tell the shader how much reflectivity the material should have if you are facing straight on. Corona glossiness is not linear, when you go bellow 0.6. The glossiness values are pretty much exponential from my tests.
Let's hope that I foresee the future and that glossiness and IOR will be one single map that respect micro shadowing.

This test use 0.5 Glossiness.

(https://i.imgur.com/c1w4zb8.jpg)

Im trying to move my workplace onto an ACES workflow and i was wondering if anyone can explain if theres anything that im supposed to be doing with textures?

ACES is something that is applied after the fact. That's the whole points of ACES. You can take a photo with a shity camera, render a linear CGI scene, record some video on your phone. It doesn't matter what color space or format you use, everything is converted into ACES, and everything will work in harmony when you composite.

Also @Dubcat are you still working on the paint LRV LUT? Id be interested to see a step by step tutorial!

I have a whole page dedicated to factory paints on my new site (still in beta), all the values already have IOR 1.5 factored into the value. You only have to sample the value with Corona Picker. If only I had this page 15 years ago!

edit: fixed 3 typos, I bet there are more!
Title: Re: dubcats secret little hideout
Post by: Jpjapers on 2019-01-13, 02:09:56
Thanks for the insightful answers as always! I noted after i posted about the ACES texture workflow that the textures id been having issues with had incorrect gamma rather than being a grading issue!. Do you have a link to your site perhaps?
Title: Re: dubcats secret little hideout
Post by: bluebox on 2019-01-13, 12:02:57
Hey Dubcat! I saw on trello, that the Corona Team wants to build new PBR shader. With all your immense knowledge of this stuff I think it would be great if you could participate in that proces to at least some degree. Not sure if anyone from the team follows this thread. Maybe you could reach out to the team ?
Title: Re: dubcats secret little hideout
Post by: Fluss on 2019-01-13, 13:02:30
In the future, I hope that render engines will fuse "PBR" and "scanned cross specular" into glossiness. Right now PBR glossiness reduce IOR at lower glossiness values, but it's global and ignore micro shadowing.
My ultimate wish right now would be to get Diffuse Roughness in Corona, and then get some kind of futuristic PBR + scanned cross specular interaction into glossiness for micro shadowing. This would not break the current PBR workflow and/or maps, but only improve them.

Hey Dubcat, can you elaborate about this? I'm not sure I get it.

edit : Here is what I understand : Basically you're asking a slot to input cross polarized specular scan in order to modify the microfacets distribution, is that right?
Title: Re: dubcats secret little hideout
Post by: Fluss on 2019-01-13, 15:48:42
I also want to add that to transpose real-world scene referred data to render scene referred data, you'll at least need to thoroughly stick to energy conservation AND preservation principles. And in that way, Corona is really far from producing accurate results.
Indeed, as roughness increase, we're losing an insane amount of energy. I've made a quick furnace test to check that out we're losing close to 50% 60% energy at high roughness values (well we cannot completely disable fresnel, but that's close enough to see the issue). Even if it still not perfect, Fstorm did a way better job on that side (It actually produce more energy than what it received but the gap is smaller tho).
Title: Re: dubcats secret little hideout
Post by: bluebox on 2019-01-13, 15:55:40
I'm not that much of a tech guy, but I really appreciate super much and respect you guys for sharing all that knowledge here and moreover developing your studies.

Once more I think you should reach out with your findings to the team so the shader that (I hope) is being developed will be as good as it can be.

A question Fluss - lets say we have a very long and narrow room with a window on one end. Does what you imply - that Corona does a poor job at maintaining the energy conservation rule - mean that it will be darker at the other side of the room than let's say in Fstorm (of course with the same camera exposure etc.) ?
Title: Re: dubcats secret little hideout
Post by: Fluss on 2019-01-14, 13:40:40
A question Fluss - lets say we have a very long and narrow room with a window on one end. Does what you imply mean that it will be darker at the other side of the room than let's say in Fstorm (of course with the same camera exposure etc.) ?

I guess it shouldn't affect light propagation that much but rougher materials will appear brighter so overall you should have the feeling that light goes a bit further yes.

what you imply - that Corona does a poor job at maintaining the energy conservation rule

To clarify, Corona team does it the right way and that's totally expected for a single scattering BRDF. That's one of the drawbacks of this kind of implementation. It looks like they've implemented some energy compensation tech for the transmission part already as it doesn't seem to darken when the roughness increase (have to be checked tho, I've made some quick tests a loooooong time ago). And I guess they tried to solve the issue on the specular part and that it was the reason why the glossiness range got fucked up before v1.5, as disabling the PBR checkbox in the shader produces a near perfect furnace test (except edge darkening/brightening).
So basically, it would be really nice to get energy preservation for both specular and diffuse lobes.

You can look at this video to see the phenomenon involved (a lot of the examples are on the transmission lobe, but it's the same for specular and diffuse lobes):


I've already submitted the idea a long time ago and devs checked it and told that this would introduce a massive overhead. But it looks like Sony Imageworks did a pretty decent job to solve that issue and I think that's worth considering. Notice that I've made the distinction between energy conservation and energy preservation. Even if it seems a bit cumbersome, that's how they've described it in their presentation and it's finally a pretty way to focus the incriminated phenomenon.

Have a look at their presentation for more info: https://blog.selfshadow.com/publications/s2017-shading-course/imageworks/s2017_pbs_imageworks_slides_v2.pdf

Also, Stephen Hill made interesting Blog posts on the subject :

Title: Re: dubcats secret little hideout
Post by: Fluss on 2019-01-14, 14:25:36
Here is an example :

0.9 glossiness :

(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=96578;image)

0.1 glossiness :

(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=96580;image)

As you can see, we're losing an incredible amount of energy here. I'll let you guess the impact of such behavior on an interior render.
Title: Re: dubcats secret little hideout
Post by: pokoy on 2019-01-14, 15:37:14
Wait, so this happens not only for refraction but reflection, too? Heck, it almost hurts physically. I wish we could settle the BRDF shortcomings for good rather sooner than later.
Title: Re: dubcats secret little hideout
Post by: Fluss on 2019-01-14, 15:53:07
Basically, every micro-faceted BRDF so diffuse, specular and transmission (including clear coat, thin surface etc etc..). We know new shader is gonna come soon so maybe this will be addressed at some point. That would make Corona an absolute killer TBH.
Title: Re: dubcats secret little hideout
Post by: Fluss on 2019-01-15, 16:25:47
Here is a more practical example demonstrating the difference between GGX and multiscatter GGX implementation of the blender's Disney principled BRDF

(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=96710;image)
Title: Re: dubcats secret little hideout
Post by: arqrenderz on 2019-01-15, 23:47:52
Dubcat has a website??? where??!

"I have a whole page dedicated to factory paints on my new site (still in beta),"
Title: Re: dubcats secret little hideout
Post by: dubcat on 2019-01-16, 00:25:27
Do you have a link to your site perhaps?

Hey!

There are still a couple of pages I need to write before the site goes public.

Here is a little preview of the calibrated paint page.

(https://i.imgur.com/BgVP5uQ.jpg)

It's one thing to calibrate swatches to real world LRV, but the most important step is to remove IOR.
IOR really de-saturates colors (If they are middle dark++). Everyone will notice this the first time they cross specular scan something.

LRV = Value in Corona Color Picker and this value is linear. It's just plain stupid that the "sRGB" check box does not affect Value in "Corona Color Picker" yet.

(https://i.imgur.com/7TleguI.png)

Maybe you could reach out to the team ?

Hey!

Ondra and the dev team have direct contact to me, so if they ever need anything they know I'll be there.

Hey Dubcat, can you elaborate about this? I'm not sure I get it.

Basically you're asking a slot to input cross polarized specular scan in order to modify the microfacets distribution, is that right?

Hey man!

I want to merge Glossiness/Roughness and IOR/Specular into one map (aka Roughness/Glossiness, it will not degrade the current real world scanned material PBR system in anyway, only improve it). Because we are already 50% there. The lower pbr glossiness value we use, the lower the IOR gets, but this is a global change. The glossiness IOR change does not go above or bellow the initial value (If we use asphalt as an example, it does not respect gem stones in the scan, or micro shadows. Micro shadowing is the #1 error that has to be fixed in CGI imho beside Coronas diffuse roughness ( ͡° ͜ʖ ͡°) ), but kinda act like reflection level did before pbr. Like when you change the opacity of a layer in Photoshop.

I made a quick and dirty proof of concept material for you guys, to show what I mean.

(https://i.imgur.com/QyIMToI.jpg)

I don't know if the Corona Curve settings get saved with the material preset, I guess so. But just in case, here is the curve.
We really need X/Y value inputs in Corona Curve!

(https://i.imgur.com/dOedAiz.jpg)

edit: Fixed a mistake in the material.

I also want to mention that the super blurred texture in the "High Pass" section has to be Corona Bitmap with 9999999442119689768320106496 Blur value. 3dsmax bitmap can't blur this much.
We really need a "gaussian blur" function in one of the Corona maps, I made a request on mantis a year or so ago. This feature is the only thing that is halting my mask generator, because we have to gaussian blur procedural maps.
Title: Re: dubcats secret little hideout
Post by: Fluss on 2019-01-16, 14:32:31
OK dubcat, got it, thanks!

I have a few questions :

From my test, corona seems to map the value as 1/IOR only when the input is below 1 (so in the sRGB range). Every value above 1 seems to be treated as a proper IOR value. So if you're inputting 1.5 linear value in the Fresnel IOR slot, you should end up with the right result. That's actually quite smart as the lowest IOR value of 1 (linear) is the highest value in sRGB range (255=1.0). So 1.0, the only common value of the two range( [0,1] ; [1,999] ) give the same result (1/1=1). It works with a corona color plugged right into the fresnel slot but as far as I try to mix two linear values together, the IOR is completely messed up, despite the fact that the "perform mixing in sRGB space" checkbox is unticked. Do you have any insight about that? That's totally freaking me out! It would be so much easier to work with linear data directly..

Also, don't you think the glossiness darkening induced by single scattering GGX is kind of a blocker here? I mean, when I look at a linear RAW DSLR picture, it's really flat. We are loosing up to 60% energy on low glossiness values, which bring a lot of contrast (not to mention that it's physically nonsense). If we're aiming at photorealism, especially using real scan data, this phenomenon should have a pretty big impact here.

Finally, as you said, Micro shadowing most of the time overlooked. If it's not that much an issue on close up shots like in your examples but as soon as we move away, filtering comes to action and we're loosing all the micro détails when using bump/normal and micro-displacement maps, resulting in a flat/plasticy render. So translating bump/micro-disp/normal map to microfacets is a must have too. It can also be declined to solve some artifacts introduced with normal mapping with BDPT algorithm (Bump/normal mapping is not reciprocal). And that's what bump to roughness does with no negative impact on render time. These examples speak by themselves :

Bump to roughness :

(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=96858;image)

Normal to roughness :

(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=96860;image)

Regular bump :

(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=96862;image)

Bump to roughness :

(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=96864;image)



Quote from: PIXAR link=https://renderman.pixar.com/stories/cars-3

"We noticed a significant improvement on environment detail, especially surfaces such as concrete and marble,"


Quote from: PIXAR link=https://renderman.pixar.com/stories/cars-3

"Typically with Marble, we try to avoid a glassy look, where the marble is too shiny. With Bump-Roughness we were able to capture all the subtle imperfections that give marble its most distinctive properties,"


Quote from: PIXAR link=https://renderman.pixar.com/stories/cars-3

"The benefits don't stop there, as previously mentioned, Cars 3 saw huge improvements in render times. Bump-Roughness is over 35% faster than bump alone"

Title: Re: dubcats secret little hideout
Post by: Fluss on 2019-01-16, 14:42:25
Also, have you tried to change the exposure between renders with the node graph you provided plugged in the IOR slot? Render->Lower exposure by let's say 2 stops->re-render. I have some weird inconsistent results under different exposures here. Everything is fine when you generated IOR map is unplugged. Let me know if you observe any issue or if it is on my side.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2019-01-24, 00:55:43
Hey Fluss!

"perform mixing in sRGB space" checkbox is unticked. Do you have any insight about that?

I tried 2 multiplied with 0.75 and 1 pluss 0.5 and they seemed to give me 4% IOR. I used the latest Daily Build.
I use the 1/IOR method in my Substance Designer generator since my maps will work in multiple render engines. This proof of concept was based on that generator. For people who are reading this later, feel free to simplify the material with pure float values as Fluss mentioned.

single scattering GGX is kind of a blocker here

When I generate my IOR maps with my Substance Designer generator, it takes into account the global PBR IOR reduction (glossines value). So it only enhances the micro shadows or gem stones in the material. If a 4% flat material has 3% because of the PBR glossiness, it will still be 3% when you use the IOR map. This is something Corona could do behind the scenes, since they know what IOR and Glossiness value we are using in the material.

Finally, as you said, Micro shadowing most of the time overlooked.

For sure!

Bump/Normal to IOR is kind of inferior to "Cross Polarizing" to IOR. Since it is only height based and not specular, (while Cross Polarizing also takes height into account, if we use scanned data), but I would not say no to a height based feature in our current state.

Megascans official specular maps are generated from normal maps, and they kinda have this flat plastic feel that you are talking about (I always associate this feel with Elder Scrolls Oblivion). The next major Quixel Bridge update will include my Roughness to IOR LUT + my latest script for Corona (Metal and Fabric support). Corona is the only engine that support all this stuff, because we have devs that actually listen to user requests.

Here is an example from my generator with roughness and normal map as input, you can see the plastic feeling you get from normal maps (height to IOR).

(https://i.imgur.com/Ng5Ir52.jpg)

Also, have you tried to change the exposure between renders with the node graph you provided plugged in the IOR slot? Render->Lower exposure by let's say 2 stops->re-render. I have some weird inconsistent results under different exposures here. Everything is fine when you generated IOR map is unplugged. Let me know if you observe any issue or if it is on my side.

I generate all my maps in Substance Designer, this was only a quick port to 3dsMax as a proof of concept. Maybe Corona Curve map has the same issues as the LUT map had before ? I hope not :( I can do some tests later this week, if you don't want to.

EDIT:
I've added a Photoshop action script that convert normal maps to height info. You can then plug this into the highpass chain in my proof of concept material.
Title: Re: dubcats secret little hideout
Post by: Jpjapers on 2019-01-24, 14:15:34
How do you have such knowledge of the technical aspects of lighting and shading? Id like to have a deeper understanding of it and wondered if you could recommend any resources?
Im warming to the idea of being a Lighting/Shading TD at some point in my career as i really enjoy the technical side of the industry. Any recommendations would be very much appreciated!
Title: Re: dubcats secret little hideout
Post by: Fluss on 2019-01-24, 16:25:30
For people who are reading this later, feel free to simplify the material with pure float values as Fluss mentioned.

There is a really strange behavior I cannot explain. After further testing, it looks like it's the 1/IOR part that not working here. On the render result at least as the material preview and the rendered material do not follow the same behavior. Here are some examples demonstrating the issue :

No IOR map plugged (IOR 1.5 in the material) :

(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=97352;image)

1.5 IOR linear float corona color plugged in, work as intended :

(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=97354;image)

Mixing 1.1 to 1.8 linear float using your node graph, the material preview is fucked up but render looks fine to me :

(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=97356;image)

Mixing using the 1/IOR method, the material preview looks fine but render does not :

(https://corona-renderer.com/forum/index.php?action=dlattach;topic=13398.0;attach=97358;image)


I have the feeling that there is some weird gamma related stuff behind that.


For the glossiness darkening and for the plasticy bump feeling, I'm not sure we are talking about the same stuff (see my previous posts).
Title: Re: dubcats secret little hideout
Post by: Fluss on 2019-01-25, 02:02:26
Hey dubcat,

Looks like the exposure inconsistency is related to the gamma 2.2 part in the IOR mask generation. Why did you choose to perform those operations in gamma 2.2 to put it back into gamma 1.0 afterward? To my knowledge, playing with gamma while performing arithmetic in a node tree that is supposed to be plugged in a linear input always end-up in a bad way, especially with data as sensitive as IOR.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2019-01-31, 02:45:12
There is a really strange behavior I cannot explain. After further testing, it looks like it's the 1/IOR part that not working here. On the render result at least as the material preview and the rendered material do not follow the same behavior.

Weird stuff.

This is how it is supposed to look like when you use my setup

(https://i.imgur.com/W3HqwRc.jpg)

And this is how a normal Corona material looks like without the IOR combo. A reflection pass that only a mother can love.

(https://i.imgur.com/BErKWW0.jpg)

Looks like the exposure inconsistency is related to the gamma 2.2 part in the IOR mask generation.

From the screenshots it looks like you didn't plug the highpassed linear roughness map into the mask slot ? Hard to tell since the screenshot is clipped off.


This material is a perfect example on why we should use cross specular maps as IOR maps https://quixel.com/assets/tbxkajlk

edit:
I overlooked the first response, sorry!

How do you have such knowledge of the technical aspects of lighting and shading?

It all began with Half Life 1 and Sims 1. The first thing I noticed when making textures for these games, was that I could have a static camera and move a light around (at the same distance). Then I could blend multiple photos together with "Lighten", this blending mode will only lighten dark pixels (shadows) and make an "albedo". Back then I didn't know what an albedo was, but it was good enough to import into Wally and make a .wad. I used to hang my cloths up, take a picture and then use the transform tool to turn them into the Sims 1 skin format, good times.

Half Life 2, Doom 3 and Oblivion opened my eyes when it comes to normal map and parallaxing effect. fStrorm still does volume displacement, and it's
 fuc***g awesome. https://fstormrender.ru/manual/displacement. Ever wondered why fStorm users can use displacement on every single plant in their interior, and why the displacement only take like 400mb instead of 200 gazillion terabytes ? This is why.

When Quixel began posting beta versions of roughness, I understood that the next step was to get my hands on some polarizing filter. You can get good quality sheets from https://www.polarization.com/polarshop. I still use sheets from these guys, even though I have to pay almost double the prize in tax, only to import it.

Since then I've been doing SSS, IOR and albedo tests on my own.
When it comes to SSS. Shorter wavelengths (blue) gets scattered more easily than red light. This is why skin looks red when you shine a light thought it, not because of the red blood. Scatter color in render engines should only be monochrome or blue to be physical correct.

You already know my view on glossiness/ior integration. Again, download https://quixel.com/assets/tbxkajlk and have a look at the glossiness map. This is not possible with normal maps.
Title: Re: dubcats secret little hideout
Post by: Jpjapers on 2019-01-31, 10:26:33
Fstorm has so many useful features like that and I wish they were higher on the agenda for corona.
Title: Re: dubcats secret little hideout
Post by: Fluss on 2019-01-31, 15:42:13
From the screenshots it looks like you didn't plug the highpassed linear roughness map into the mask slot ? Hard to tell since the screenshot is clipped off.

It was plugged in, that's a gamma issue for sure, I'll prepare you an explanation of what's going on.

FStrorm still does volume displacement, and it's fuc***g awesome. https://fstormrender.ru/manual/displacement. Ever wondered why fStorm users can use displacement on every single plant in their interior, and why the displacement only take like 400mb instead of 200 gazillion terabytes ? This is why.

Yep, Fstorm displacement is great (the only drawback is that it does not handle procedurals)! we discussed that in this thread: https://corona-renderer.com/forum/index.php?topic=22625.0
Title: Re: dubcats secret little hideout
Post by: noldo on 2019-02-02, 10:20:48
Hi Dubcat!
I am an octane render user, but this post is very interesting!!!
I think your "Specular To Ior v.2" LUT is a bit broken (sorry for my english)
If i convert a sRGB 59 grayscale image (1.5 IOR), the lut give me a value of 167.
I think the correct value is 170 (1/IOR = 1/1.5 = 0.6666666666 => 0.666666666x255=170).
Seems your LUT multiply the value x 250 instead of 255.
Thanks for your work!

P.s. Maybe my fault, wrong monitor color profile?

P.p.s. After some more investigation, i found a way to convert specular to IOR map in octane, but i think corona treat the IOR map the same way (a grayscale value that represent 1/IOR value)
I connected in nuke an expressioni to the specular map with the following formula "1/((r+2*sqrt(r)+1)/(1-r))", then connect the output to a writer image.

P.p.p.s. Your LUT is correct, my fault, i don't understand why 167 instead 170... Bah!
Title: Re: dubcats secret little hideout
Post by: dubcat on 2019-02-03, 04:42:46
Fstorm has so many useful features like that and I wish they were higher on the agenda for corona.

For sure!

It was plugged in, that's a gamma issue for sure, I'll prepare you an explanation of what's going on.

Me and Fluss will be having some direct messaging. Just letting you guys know, so you don't think I'm an asshole that ignore all his posts :P

P.p.p.s. Your LUT is correct, my fault, i don't understand why 167 instead 170... Bah!

Hehe, I feel you! 3dsmax slate and linear/srgb is a real pain in the ass. Software that compile LUTs are also a pain in the ass, there is no standard.
I will be supporting Corona/Vray/fStorm/Octane/Renderman and Blender 2.8 on my site in the end. (Corona is always first priority)
I have high hopes for Blender 2.8, finally I can click on that damn default cube with my left mouse button and delete it. Can't wait to code my procedural mask generator!
Title: Re: dubcats secret little hideout
Post by: Jpjapers on 2019-02-04, 21:00:25
I remember you did a thread on virtual colour checkers.
How would that work with ACES Emulation?
Would you apply aces settings and your LUT and then use the output in lightroom to calibrate?
Colour management is all very new to me but its infinitely fascinating to get into the process of making sure my work output is accurate.
Title: Re: dubcats secret little hideout
Post by: dubcat on 2019-02-08, 04:08:15
I remember you did a thread on virtual colour checkers.
How would that work with ACES Emulation?
Would you apply aces settings and your LUT and then use the output in lightroom to calibrate?
Colour management is all very new to me but its infinitely fascinating to get into the process of making sure my work output is accurate.

Hey!

I would capture a color checker passport at your current light intensity. Generate a camera profile. If your profile has a contrast curve, open it in 3DLUTCreator and remove it. This should give you a calibrated color and linear camera profile.
When you have a calibrated profile. The only thing you should care about is linear values. When it comes to real world albedos, we talk in linear %. If I tell you the brightest common paint is 94%, you should be able to input that value into "Value" in Corona Picker. But that is not how Corona Picker is working right now. So you have to convert 94% to sRGB. If you are thinking, why the hell do we have to gamma correct a linear value only to get a linear value, ask the Corona devs, it blows my mind every day. 94% is 97.2% sRGB, so this is the max real world scanned common paint value.

Another problem we have with the current Corona Picker is that the darkest common paint is "Jet Black" and it's 14,14,16 sRGB. Try to input these values into Corona Picker. You end up with 0,0,24 sRGB. This is a common problem when we try to sample real world values for products, the sRGB values might jump 10 sRGB. I'm using Vrays color map to fix this, because it let me adjust values separately with float values.


-----------------------------------------------------------------------------------------------------------------------
edit:

I haven't had much time to complete the last few guides on my site. But I want to share paint values with you guys as soon as possible, so I have remove all the unfinished stuff from the site.
I've only had time to add the 2019 Color Chart paints to the page, but have about 1 gazillion paints ready.
If you have a paint value, and are wondering how it would look with LRV and - IOR. Just post the values here, and I'll add them to the page when I get time.

https://dubcatshideout.com/ (https://dubcatshideout.com)
Title: Re: dubcats secret little hideout
Post by: IsmaeL on 2019-02-08, 09:51:50
The site looks amazing, specially the Home Page XD
I have one concern tough, what is with the minimum Black value. Corona Color Picker tells me it's 0. From what I was taught you should never use 0 as Black. Am I wrong or did I miss the point??

As for colors, I have a bunch of RAL and NSC colors I use for my clientes. They are all in the furnishing business, so for industrial purposes RAL and NSC is used a lot.

Reading about the color checker reminds me, I have to shoot images of marble textures. I am a bit scared since I'm not sure I'm doing this right.
So I have a full-frame camera with 36 MP, unfortunately that is the max I could get. Would have loved to have a medium size CMOS, but that is to expensive.
Everything is set up, have a color passport, 5 mm lense and remote control for the camera.

What would you suggest I do with the images I get from this. Do I need a camera profile? or will the RAW files be enough to work with?
Would love to here some input form you. Thanks
Title: Re: dubcats secret little hideout
Post by: romullus on 2019-02-08, 10:48:12
Another problem we have with the current Corona Picker is that the darkest common paint is "Jet Black" and it's 14,14,16 sRGB. Try to input these values into Corona Picker. You end up with 0,0,24 sRGB. This is a common problem when we try to sample real world values for products, the sRGB values might jump 10 sRGB. I'm using Vrays color map to fix this, because it let me adjust values separately with float values.

But you can do that with CoronaColor texmap too, why use Vray's map?
Title: Re: dubcats secret little hideout
Post by: Nate101 on 2019-02-08, 20:05:47
Nothing to add to discussion but wanted to say thanks to dubcat for creating the site and for all the incredible information in this thread.  90% goes over my head but fascinating read nonetheless.

PS, dubcat I tried to PM you but said message blocked?
Title: Re: dubcats secret little hideout
Post by: James Vella on 2019-02-09, 08:34:47
Another problem we have with the current Corona Picker is that the darkest common paint is "Jet Black" and it's 14,14,16 sRGB. Try to input these values into Corona Picker. You end up with 0,0,24 sRGB. This is a common problem when we try to sample real world values for products, the sRGB values might jump 10 sRGB.

Why not just use the hex color code if you want to match the paint in the corona color picker? Still a workaround but none the less it gives accurate results correct?

Title: Re: dubcats secret little hideout
Post by: Jpjapers on 2019-02-09, 08:56:01
Another problem we have with the current Corona Picker is that the darkest common paint is "Jet Black" and it's 14,14,16 sRGB. Try to input these values into Corona Picker. You end up with 0,0,24 sRGB. This is a common problem when we try to sample real world values for products, the sRGB values might jump 10 sRGB.

Why not just use the hex color code if you want to match the paint in the corona color picker? Still a workaround but none the less it gives accurate results correct?

I think the issue here is you dont know the hex code until you convert your paint colour and LRV properly if my understanding is correct?

Also FYI Dubcat when i picker jet black from the site I get 14,14,14 not 14,14,16
Title: Re: dubcats secret little hideout
Post by: James Vella on 2019-02-09, 09:38:33
you can just download the paint swatch, open it in photoshop and it gives you the hex code. You can then plug this into corona color map. If your scene is already calibrated it will come out 1:1
Title: Re: dubcats secret little hideout
Post by: Jpjapers on 2019-02-09, 09:56:19
you can just download the paint swatch, open it in photoshop and it gives you the hex code. You can then plug this into corona color map. If your scene is already calibrated it will come out 1:1

Ah see this is the issue. The paint swatches online already have simulated LRV alot of the time. Dubcat did a post about it https://corona-renderer.com/forum/index.php?topic=13398.msg124782#msg124782 (https://corona-renderer.com/forum/index.php?topic=13398.msg124782#msg124782)
Title: Re: dubcats secret little hideout
Post by: romullus on 2019-02-09, 10:13:09
@jpjapers, me and James Vella are pointing to dubcat's statement that Corona picker does not let to pick very low sRGB values without rounding them to nearest RGB values. This issue can be overcome with Corona Color node either through solid HDR colour, or through HEX colour. What you're talking about, is completely different thing.
Title: Re: dubcats secret little hideout
Post by: Jpjapers on 2019-02-09, 10:34:22
@jpjapers, me and James Vella are pointing to dubcat's statement that Corona picker does not let to pick very low sRGB values without rounding them to nearest RGB values. This issue can be overcome with Corona Color node either through solid HDR colour, or through HEX colour. What you're talking about, is completely different thing.

I get it but he mentioned downloading the paint swatch and opening in photoshop but as i understand theres a reason you dont do that? Or have i misunderstood?
Title: Re: dubcats secret little hideout
Post by: romullus on 2019-02-09, 10:50:17
You can't sample that swatch with Corona picker because of afforementioned rounding issue, so you have to download it to photoshop and read sRGB values there. Swatches with higher values, can be picked with Corona picker directly.

Edit: i think it would be best if dubcat would write sRGB values next to each slot, so it could be useful even for people who doesn't use Corona picker, or doesn't have second monitor or are too confused in which mode to sample colours (sRGB or RGB).
Title: Re: dubcats secret little hideout
Post by: Jpjapers on 2019-02-09, 15:48:40
You can't sample that swatch with Corona picker because of afforementioned rounding issue, so you have to download it to photoshop and read sRGB values there. Swatches with higher values, can be picked with Corona picker directly.

Edit: i think it would be best if dubcat would write sRGB values next to each slot, so it could be useful even for people who doesn't use Corona picker, or doesn't have second monitor or are too confused in which mode to sample colours (sRGB or RGB).

Oh my bad i was talking about swatches from manufacturers not from his site
Title: Re: dubcats secret little hideout
Post by: James Vella on 2019-02-09, 19:32:21
It makes no difference where you get the swatch from as long as the RGB values correlate. I just used windows snipping tool, saved the jpg to the desktop and open it in photoshop.

You can see here the swatch from the Dulux website for "Scotts Pine"
https://www.dulux.com.au/specifier/colour/colour-atlas#!/colour/dulux_dulux_21849

RGB = R: 96, G: 101, B: 58
HEX: #60653a

Attached is the photoshop color picker, the dulux website screenshot, and corona vfb render & corona color node
Title: Re: dubcats secret little hideout
Post by: dubcat on 2019-02-09, 22:31:26
Why not just use the hex color code if you want to match the paint in the corona color picker? Still a workaround but none the less it gives accurate results correct?

If you already have the paint value with correct LRV and - IOR, this solution works fine. The paint swatches that most companies use in Norway do not factor LRV/IOR.

You can see here the swatch from the Dulux website for "Scotts Pine"

Looks like Dulux take LRV and IOR into account on their online swatches, if only all paint manufactures did this.

(https://i.imgur.com/QqYaofC.png)

But you can do that with CoronaColor texmap too, why use Vray's map?

The thing with CoronaColor is that if you switch to "Solid HDR color", it overwrites the color you have sampled. While VrayColor does not force any workflow, you can sample the color and still have linear float.

(https://i.imgur.com/OGWGQrQ.png)
Title: Re: dubcats secret little hideout
Post by: Jpjapers on 2019-02-09, 22:45:13
It makes no difference where you get the swatch from as long as the RGB values correlate. I just used windows snipping tool, saved the jpg to the desktop and open it in photoshop.

You can see here the swatch from the Dulux website for "Scotts Pine"
https://www.dulux.com.au/specifier/colour/colour-atlas#!/colour/dulux_dulux_21849

RGB = R: 96, G: 101, B: 58
HEX: #60653a

Attached is the photoshop color picker, the dulux website screenshot, and corona vfb render & corona color node

Well that's good news baing in the Uk myself. I didn't realise they provided a hex code.
Title: Re: dubcats secret little hideout
Post by: James Vella on 2019-02-09, 23:05:15

Well that's good news baing in the Uk myself. I didn't realise they provided a hex code.

They don't provide the hex code, i got it from photoshop, u sample it from the swatch as u can see in the screenshots i posted above
Title: Re: dubcats secret little hideout
Post by: Jpjapers on 2019-02-09, 23:06:51

Well that's good news baing in the Uk myself. I didn't realise they provided a hex code.


They don't provide the hex code, i got it from photoshop, u sample it from the swatch as u can see in the screenshots i posted above


Sorry I meant RGB values. Brainfart!
Title: Re: dubcats secret little hideout
Post by: dubcat on 2019-02-16, 02:02:38
I've been analyzing a bunch of professional Scandinavian interior photos (that still contained lightroom exif data, we can extract this data, and remake the original photo. It won't be 1:1 to the original, but it will get us in the ballpark), and this is the average color matrix they all use.
I was wondering how close we could get to this color matrix using Corona VFB Saturation. -0.075 seem to get us pretty close.
I found it interesting that Coronas VFB Saturation is not "linear" in the way that all the colors get reduced (You can see that blue gets reduced more). I'm not complaining (since this is how the photos are behaving), just found it interesting.

(https://i.imgur.com/jiG8wNJ.png)
Title: Re: dubcats secret little hideout
Post by: Jpjapers on 2019-02-16, 20:11:19
I've been analyzing a bunch of professional Scandinavian interior photos (that still contained lightroom exif data, we can extract this data, and remake the original photo. It won't be 1:1 to the original, but it will get us in the ballpark), and this is the average color matrix they all use.
I was wondering how close we could get to this color matrix using Corona VFB Saturation. -0.075 seem to get us pretty close.
I found it interesting that Coronas VFB Saturation is not "linear" in the way that all the colors get reduced (You can see that blue gets reduced more). I'm not complaining (since this is how the photos are behaving), just found it interesting.

(https://i.imgur.com/jiG8wNJ.png)

Interesting!
Title: Re: dubcats secret little hideout
Post by: Jpjapers on 2019-02-19, 18:01:35
I remember you did a thread on virtual colour checkers.
How would that work with ACES Emulation?
Would you apply aces settings and your LUT and then use the output in lightroom to calibrate?
Colour management is all very new to me but its infinitely fascinating to get into the process of making sure my work output is accurate.

Hey!

I would capture a color checker passport at your current light intensity. Generate a camera profile. If your profile has a contrast curve, open it in 3DLUTCreator and remove it. This should give you a calibrated color and linear camera profile.
When you have a calibrated profile. The only thing you should care about is linear values. When it comes to real world albedos, we talk in linear %. If I tell you the brightest common paint is 94%, you should be able to input that value into "Value" in Corona Picker. But that is not how Corona Picker is working right now. So you have to convert 94% to sRGB. If you are thinking, why the hell do we have to gamma correct a linear value only to get a linear value, ask the Corona devs, it blows my mind every day. 94% is 97.2% sRGB, so this is the max real world scanned common paint value.

Another problem we have with the current Corona Picker is that the darkest common paint is "Jet Black" and it's 14,14,16 sRGB. Try to input these values into Corona Picker. You end up with 0,0,24 sRGB. This is a common problem when we try to sample real world values for products, the sRGB values might jump 10 sRGB. I'm using Vrays color map to fix this, because it let me adjust values separately with float values.


-----------------------------------------------------------------------------------------------------------------------
edit:

I haven't had much time to complete the last few guides on my site. But I want to share paint values with you guys as soon as possible, so I have remove all the unfinished stuff from the site.
I've only had time to add the 2019 Color Chart paints to the page, but have about 1 gazillion paints ready.
If you have a paint value, and are wondering how it would look with LRV and - IOR. Just post the values here, and I'll add them to the page when I get time.

https://dubcatshideout.com/ (https://dubcatshideout.com)

How do you generate your profile?
Ive tried lightroom but it wont open exr and colour passport wont run on non raw formats.
3DLUT creator gives some really horrible results with the passport.

Is there any way you could give a slightly more in depth explanation of using it?
In terms of VFB setup, export format, and process to generate your DNT/LUT?
Title: Re: dubcats secret little hideout
Post by: JViz on 2019-03-14, 00:45:32
very interesting so far. I'm at page 17 of this enormous very informative post. do you discuss how to remove lighting and reflection from a texture -taken by a camera- to get the Albedo?
Title: Re: dubcats secret little hideout
Post by: Fluss on 2019-03-26, 14:27:32
I think it's the best place for this. This is one of the best synthesis of what should characterize an uber shader I've seen so far. Enjoy !

https://autodesk.github.io/standard-surface/
Title: Re: dubcats secret little hideout
Post by: tegokg on 2019-05-06, 22:45:14
Yoo guys, I'm kinda new here, and have some question [I belive its right place to ask it here]. On this thread in this post https://corona-renderer.com/forum/index.php?topic=13398.msg95061#msg95061, Dubcat talked about "Angle Affect" feature. And to me is not completly clear how this shader three works, and what values i should use [i'm most interested in output node, and the color node with 1.8 value]. Sorry if i jack yours current conversation.

Best regards JT
Title: Re: dubcats secret little hideout
Post by: niljut on 2019-05-07, 09:54:34
Yoo guys, I'm kinda new here, and have some question [I belive its right place to ask it here]. On this thread in this post https://corona-renderer.com/forum/index.php?topic=13398.msg95061#msg95061, Dubcat talked about "Angle Affect" feature. And to me is not completly clear how this shader three works, and what values i should use [i'm most interested in output node, and the color node with 1.8 value]. Sorry if i jack yours current conversation.

Best regards JT

I am fairly certain the CoronaColor is set to Solid HDR Color with 1.8 in R, G, and B, making the CoronaMix multiply your original glossiness values by 1.8x. This would make values above 141 go beyond 255, so the output has clamp enabled to bring those values down to 255.
Title: Re: dubcats secret little hideout
Post by: tegokg on 2019-05-08, 21:04:36
Thank you very much Sir.

Best regards JT
Title: Re: dubcats secret little hideout
Post by: Jpjapers on 2019-05-09, 17:01:36


(http://i.imgur.com/YgEYeZ0.png)

and this is how you can emulate fStorms "Angle Affect" option in Corona

(http://i.imgur.com/8XXcYi9.png)



Can anyone explain this shader tree?
There seems to be no detail in this thread about what the corona colour node marked 1.8 is.
Ive tried to recreate this and that colour seems to do absolutely nothing.

Title: Re: dubcats secret little hideout
Post by: niljut on 2019-05-10, 11:44:09


(http://i.imgur.com/YgEYeZ0.png)

and this is how you can emulate fStorms "Angle Affect" option in Corona

(http://i.imgur.com/8XXcYi9.png)



Can anyone explain this shader tree?
There seems to be no detail in this thread about what the corona colour node marked 1.8 is.
Ive tried to recreate this and that colour seems to do absolutely nothing.
To quote myself two posts ago:
I am fairly certain the CoronaColor is set to Solid HDR Color with 1.8 in R, G, and B, making the CoronaMix multiply your original glossiness values by 1.8x. This would make values above 141 go beyond 255, so the output has clamp enabled to bring those values down to 255.

The shader amplifies the glossiness at gracing angles, and yes it's subtle (most of the time).
Title: Re: dubcats secret little hideout
Post by: Jpjapers on 2019-05-10, 12:39:09


(http://i.imgur.com/YgEYeZ0.png)

and this is how you can emulate fStorms "Angle Affect" option in Corona

(http://i.imgur.com/8XXcYi9.png)



Can anyone explain this shader tree?
There seems to be no detail in this thread about what the corona colour node marked 1.8 is.
Ive tried to recreate this and that colour seems to do absolutely nothing.
To quote myself two posts ago:
I am fairly certain the CoronaColor is set to Solid HDR Color with 1.8 in R, G, and B, making the CoronaMix multiply your original glossiness values by 1.8x. This would make values above 141 go beyond 255, so the output has clamp enabled to bring those values down to 255.

The shader amplifies the glossiness at gracing angles, and yes it's subtle (most of the time).

Makes perfect sense i was missing the HDR colour bit.
Thank you!
Title: Re: dubcats secret little hideout
Post by: JViz on 2019-05-11, 05:41:33
hi dubcat! how do we get correct IOR values when we do not have a scanned glossiness texture to use it with a LUT? can we use the normal texture with a LUT?
Title: Re: dubcats secret little hideout
Post by: romullus on 2019-05-22, 12:01:50
dubcat, man, you'll have a lot of questions to answer next time you login. Here's one more from me :]

Lately there's a lot CC0 PBR textures floating around. Some are better, some are worse and some are rubbish, but almost all of them has height/displacement maps with arbitrary set midpoint grey (usually much darker). I found that pretty inconvenient, so i decided to fix them for myself. After few quick tests, i found that best results is achieved in photoshop by placing solid colour filter on top height texture and setting its blending mode to linear light or linear burn to lighten or to darken map respectively. Does that sounds correct to you? Do you also correct height maps or just adjust min/max displacement levels in Corona?
Title: Re: dubcats secret little hideout
Post by: Basshunter on 2019-06-20, 20:09:16
Hey dubcat!

It's been a long time without your presence. We miss you man.

I was wondering if you could share your opinion about what's going on with a couple of raw pictures I tried to developed using DCRAW. They were taken with my phone. I'm doing this as an experiment to help me better assimilate how a linear rendering in the VFB (without any post) should look like. The thing is that these images look horrible, almost black and white. Not even what one would expect from a linear rendering to look like.

Maybe I'm doing something wrong in the developing process. Or perhaps, I've misunderstood some concepts and this assumption of mine that linear renderings and raw photos are equivalent is wrong.

I'd highly appreciate hearing your opinion on this regard.

This is the line I've used in DCRAW to develop the pictures: -v -w -H 0 -o 1 -q 3 -4 -T
It was taken from one of your photographic LUT posts.

These are the pictures:

(https://i.imgur.com/tFuB2JD.jpg)

(https://i.imgur.com/8XWhSG4.jpg)

Original RAW files: https://we.tl/t-GHDb35EDbK


Title: Re: dubcats secret little hideout
Post by: dubcat on 2019-06-22, 04:38:54
hi dubcat! how do we get correct IOR values when we do not have a scanned glossiness texture to use it with a LUT? can we use the normal texture with a LUT?
Hey!
I have a LUT that converts old reflection maps to IOR and a Corona map setup that converts normal maps to IOR. I thought I shared it a while back, maybe I never got that far. I will compile them as soon as possible!


Do you also correct height maps or just adjust min/max displacement levels in Corona?
Hey!
I've never tried the CC0 maps. If I only have a shity 8/16bit displacement map. I usually project them in Zbrush on a plane with a height value that looks reasonable. That way I can clean the nasty artifact if there are any, and export them as a proper 32bit map. When it comes to Megascans, you can get the proper height value inside the .json file, just search for "height". I don't know if Quixel have included my latest Corona exporter in Bridge 2 yet, the script takes care of all that stuff and more.


Not even what one would expect from a linear rendering to look like.

Hey!

DCRAW is really good at everything except color profiles and noise reduction. Because of this I changed my workflow a while back. My current workflow is to generate a linear profile for my camera and load the photos in Lightroom with that custom profile. I can generate a profile for you when I get time, just tell me the manufacturer and model. I'll also compile a camera curve that you can load in Coronas VFB curve editor.



I have a lot of pages to read through!
Title: Re: dubcats secret little hideout
Post by: Basshunter on 2019-06-22, 20:14:03
I can generate a profile for you when I get time, just tell me the manufacturer and model. I'll also compile a camera curve that you can load in Coronas VFB curve editor.

Sounds great! I appreciate that. It's a Moto G6 by Motorola.

However, I'd be more interested in learning how to get the camera profile and do all the process by my self. Would you be willing to share this info?

Thanks Dubcat for this thread. I really enjoy learning through it.
Title: Re: dubcats secret little hideout
Post by: JViz on 2019-06-25, 10:54:37
hi dubcat! how do we get correct IOR values when we do not have a scanned glossiness texture to use it with a LUT? can we use the normal texture with a LUT?
Hey!
I have a LUT that converts old reflection maps to IOR and a Corona map setup that converts normal maps to IOR. I thought I shared it a while back, maybe I never got that far. I will compile them as soon as possible!


in the case of non-scan textures where a reflection or a glossiness map is eyeballed generated, is it more correct to use the normal map to generate the IOR with a LUT? I think it is, but if IOR is attached to the reflection/glossiness value and a normal map is also auto generated from photoshop or any other normal map generator, then .... (sorry for the long prelude) .... what is the correct way to getting the accurate IOR values?

thank you!
Title: Re: dubcats secret little hideout
Post by: dubcat on 2019-06-28, 04:07:28
Moto G6 by Motorola.

This is one of those rare cases where I don't have a camera profile. You can either capture a raw photo with a mobile app and we can extract the camera profile from the raw image. Or you can generate an optimal camera profile with an Xrite, and then we can linearize the generated profile.
I hope to be more active online soon, proper linear profile guide is one of my top priories.

what is the correct way to getting the accurate IOR values?

My generator is based on IOR 1.5 and will high pass all input maps. I will port my code to 3dsMax and post it here, that way you guys can make adjustments if you want. Instead of having a static LUT.
I rarely use LUTs nowadays. Most stuff can be done with Coronas Curve editor in combination with hacky stuff between the two VFB tonemappers.

Best result would be:
#1 Specular Scan (Photo real result). (Look at your TV plastic controller, when you rotate it, it will give you micro spectacular results. But when you view it direct on, it will look diffuse. This effect can not be captured with a normal map.)
#2 Normal Map (Height Based, better than nothing.)
#3 Old Reflection custom fantasy maps (Nothing to do with real world values. 99% of online stores)

I began porting the code, and where the hell has the Corona Bitmap Blur property gone ? It was the only reason for me to use Corona Bitmap, as it behaved as a super blur for highpass.
We need a corona map that has gaussian blur, this missing feature is killing a lot of dynamic and procedural map generation ideas.

edit: typo = port -> post
Title: Re: dubcats secret little hideout
Post by: Basshunter on 2019-06-29, 15:49:19
You can either capture a raw photo with a mobile app and we can extract the camera profile from the raw image.
Nice. There's a link to the RAW images in the original post.

proper linear profile guide is one of my top priories.
That would be fantastic. While this wonderful tutorial comes, would you mind to share some quick lines about how to get this linear profile and compile the camera curve into a LUT for Corona? I'd really appreciate it.
Title: Re: dubcats secret little hideout
Post by: dj_buckley on 2019-07-03, 22:43:45
It makes no difference where you get the swatch from as long as the RGB values correlate. I just used windows snipping tool, saved the jpg to the desktop and open it in photoshop.

You can see here the swatch from the Dulux website for "Scotts Pine"
https://www.dulux.com.au/specifier/colour/colour-atlas#!/colour/dulux_dulux_21849

RGB = R: 96, G: 101, B: 58
HEX: #60653a

Attached is the photoshop color picker, the dulux website screenshot, and corona vfb render & corona color node

quick tip for you mate, if you're using Chrome browser, get the extension called Eye Dropper - you can sample the colours directly within your browser and it gives RGB and Hex etc, just checked it on the Scotts Pine one and it matches the values you got from sampling in PS
Title: Re: dubcats secret little hideout
Post by: Frood on 2019-07-04, 08:46:55
get the extension called Eye Dropper

Just in case you don't know about it: you can use Corona improved Picker inside Max to sample values directly from anywhere on the screen (drag the eyedropper icon).


Good Luck




Title: Re: dubcats secret little hideout
Post by: dj_buckley on 2019-07-04, 18:27:15
get the extension called Eye Dropper

Just in case you don't know about it: you can use Corona improved Picker inside Max to sample values directly from anywhere on the screen (drag the eyedropper icon).


Good Luck

every day is a school day :)
Title: Re: dubcats secret little hideout
Post by: dj_buckley on 2019-07-04, 18:31:44
+1 on the learning of how to extract and make usable LUTS from specific camera profiles, I have a D810 and I'd love to being to extract the response curves of the various picture modes (Standard, Neutral, Flat, Landscape etc) and use them as LUTS or Curves in VFB.  It would make camera matching lighting and colours an absolute dream