Author Topic: dubcats secret little hideout  (Read 109723 times)

2019-02-09, 10:34:22
Reply #390

Jpjapers

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@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?

2019-02-09, 10:50:17
Reply #391

romullus

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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).
« Last Edit: 2019-02-09, 10:56:23 by romullus »
I'm not Corona Team member. Everything i say, is my personal opinion only.

2019-02-09, 15:48:40
Reply #392

Jpjapers

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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

2019-02-09, 19:32:21
Reply #393

James Vella

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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

2019-02-09, 22:31:26
Reply #394

dubcat

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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.



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.

             ___
    _] [__|OO|
   (____|___|     https://www.twitch.tv/dubca7 / https://soundcloud.com/dubca7 ( ͡° ͜ʖ ͡°)

2019-02-09, 22:45:13
Reply #395

Jpjapers

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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.

2019-02-09, 23:05:15
Reply #396

James Vella

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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

2019-02-09, 23:06:51
Reply #397

Jpjapers

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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!
« Last Edit: 2019-02-10, 01:25:26 by jpjapers »

2019-02-16, 02:02:38
Reply #398

dubcat

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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.

« Last Edit: 2019-02-16, 03:06:49 by dubcat »
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   (____|___|     https://www.twitch.tv/dubca7 / https://soundcloud.com/dubca7 ( ͡° ͜ʖ ͡°)

2019-02-16, 20:11:19
Reply #399

Jpjapers

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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.



Interesting!
« Last Edit: 2019-05-09, 17:13:08 by jpjapers »

2019-02-19, 18:01:35
Reply #400

Jpjapers

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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/

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?

2019-03-14, 00:45:32
Reply #401

JViz

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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?

2019-03-26, 14:27:32
Reply #402

Fluss

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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/

2019-05-06, 22:45:14
Reply #403

tegokg

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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

2019-05-07, 09:54:34
Reply #404

niljut

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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.