Author Topic: dubcats secret little hideout  (Read 109884 times)

2018-08-28, 20:58:46
Reply #285

dubcat

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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



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.



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!
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2018-08-28, 21:27:57
Reply #286

romullus

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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.
I'm not Corona Team member. Everything i say, is my personal opinion only.

2018-08-28, 21:35:13
Reply #287

dubcat

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Hey man!

I have an account, downloading right now. Will have a look at it in the coming days together with Mrazkos HDRi question :)
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2018-08-28, 22:40:37
Reply #288

romullus

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Thank you! :]
I'm not Corona Team member. Everything i say, is my personal opinion only.

2018-09-05, 22:10:28
Reply #289

Basshunter

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Hey dubcat,

Is there any chance to have an iPad Air LUT?

I'm needing it for a photomatch. Thanks

2018-09-07, 03:49:02
Reply #290

dubcat

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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.
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2018-09-07, 06:43:04
Reply #291

Basshunter

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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.

2018-09-07, 14:31:02
Reply #292

romullus

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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 :]
I'm not Corona Team member. Everything i say, is my personal opinion only.

2018-09-16, 03:54:44
Reply #293

dubcat

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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.

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2018-09-23, 02:49:39
Reply #294

dubcat

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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.



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.

« Last Edit: 2018-09-23, 03:15:12 by dubcat »
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2018-09-25, 15:01:20
Reply #295

Fluss

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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.
« Last Edit: 2018-09-25, 15:06:04 by Fluss »

2018-09-25, 15:55:19
Reply #296

Fluss

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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.


2018-09-25, 23:23:12
Reply #297

dubcat

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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.



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.



« Last Edit: 2018-09-26, 00:39:06 by dubcat »
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2018-09-26, 00:46:21
Reply #298

Fluss

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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?

2018-09-26, 01:26:52
Reply #299

dubcat

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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.



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!
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