dubcats secret little hideout

[dubcat]

[dubcat]

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



My new VFB ACES emulation



Default Corona - Yellow Sun "bug"



Fix



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".

[vemod]

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 :)

[dubcat]

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.



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



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



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!

[romullus]

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?

[dubcat]

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.



Substance Designer Node with default settings.



Quixel dDO with default settings.



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!

[A515]

DUPCAT.. David Copperfield :)thank you

[dubcat]

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



Official Megascans Specular Map converted to IOR



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.

[WAcky]

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

[dubcat]

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.

[Fluss]

Nice stuff Dubcat, as always !

[WAcky]

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.

[dubcat]

The new IOR generator is almost complete, this will be the final rev for today.

No IOR map



Old Specular to IOR map



New IOR Generator

[fabio81]

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!

[dubcat]

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.



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.