Roughness maps

[Avan]

Hello! I use a pack of textures for recreating some ground effects like this. (http://real-displacement-textures.com/info.html) But i do not know where i should put Roughness map and what can i do with IOR value. Could anyone give me the advice? I've read some information about PBR materials but it is kinda hard for me to understand all about it. I want to see the right result on material and not to use many hardware power for calculating. Texture pack hasn't got any IOR maps for converting like this way (http://polycount.com/discussion/155524/pbr-basecolor-metallic-to-vray-3-2-corona-redshift-arnold-converter). Must i choose IOR from my previous experience or use special technics for such textures pack (ground recreate)?

[dubcat]

Normally the roughness map should be an inverted version of the glossiness map, in this case it is not. My guess would be that this is for the "old" roughness that v-ray has for Blinn/Ward BRDF.

Take a look at my Substance Painter 2 Profile and Starter Guide thread for IOR / Glossiness guidelines.
You basically need to plug the glossiness map into a "GGX Output" and leave IOR at 1.5.

[Avan]

Thank you dubcat ! I've seen all of your articles at our forum already :) Great explanation. Simply i did not know all features of that type materials and corona restrictions for it.
I would like know all of this features in near future :) It is rather interesting for me and my work.

[Juraj]

My guess would be that this is for the "old" roughness that v-ray has for Blinn/Ward BRDF.

Not in this case. I don't think anyone, at any time provided such texture :- ) It is, a roughness in PRB terms.

It's his "Gloss" that throws it off, because that really is just specular texture for 1.52 IOR workflow. The incorrect way ;- )
He just combined his old workflow (clamping specularity) to PBR and kept zombie version of it.

So the correct way imho is to invert his 'roughness' map and then plug it into your setup.

[dubcat]

Juraj_Talcik is correct.
After zooming in on one of the overview pictures I see that "Gloss" is the same as "Reflection Color" and "Roughness" is the standard inverted Glossiness map.
What a mess !

I'm downloading one of the demo packs right now, need to see how these look.

[Avan]

This all look messy) If you will be able to explain how to use  this maps in a right way i'll be very thankful you. Bumps, normals and depth (displacement) working perfect. Only misunderstanding with correct IOR settings.

[dubcat]

Here is my quick little test with the demo texture.

I had to lower IOR down to 1.33, since Corona does not dim the IOR. (Maybe 1.43 or something like that would be better)



The maps should be linear, but I'm not sure if they are. I loaded them with gamma 1.0

Not flipped normal                                                                                                                                              flipped normal



EDIT: Added 1.4 IOR just for comparison.

[Juraj]

Most often with micro detail, I can't tell when normal map is incorrect.

Should we take it for granted, that every time we use modern normal map, we have to Flip Green channel (Y) by default inside Corona ?

[Ondra]

I can make the checkbox on by default, would that be OK?

[dubcat]

I can make the checkbox on by default, would that be OK?

That would be great!

[Avan]

Thanks again Dubcat ! Is there any curve tweak at your "output/ggx fix" map?

[dubcat]

Thanks again Dubcat ! Is there any curve tweak at your "output/ggx fix" map?

It's the default "GGX Output" from Corona Converter. It's also included in the .mat in the Substance thread.

[dubcat]

I've made a LUT that you can apply to any glossiness map that is using IOR 1.5. This will simulate the proper IOR dimming behavior that Coronas GGX is missing.
If your material is using Roughness, remember to invert it before you apply the LUT in Photoshop.
Load the IOR map with gamma 1.0.

This is how the cobble stone should look like with 1.5 IOR. The dirt is very rough even though it has IOR 1.5.



This is how the cobble stone look like with 1.5 IOR in Corona. The dirt is washed out and glossy.



This is how the cobble stone will look like in Corona when you use my "IOR Fix LUT". The dirt is behaving as it should, yey!



HOW TO

Apply the LUT above the Glossines map in Photoshop (Change to 16 bit for best result)



Magic



Load the IOR Fix Map with Gamma 1.0



Open in a new tab to see the difference.

[romullus]

Let's hope that Ondra and his team will bring us glossiness fix as promised soon and will make your workaround redundant :]
Excellent stuff nonetheless!

[Juraj]

That would be great.

Honestly I think this is needlessly complicated workaround (also destructive), that requires creation of new map individually for each material.

I actually remade my material library with your IOR lowering technique. So rough materials of 1.52 go to +/- 1.3 on scale of their roughness. Now the materials actually look as they should.

Still, one day I'll have to remake them again....