How to create roughness map in photoshop?

JordanN

I wanted to make a new thread because I though this question was technical (and I tried checking polycount wiki for an answer).



I'm looking at this person's physically based workflow and I need to know which colors represent roughness/smoothness and how can I create it in photoshop.

AndyLittleton

I think you'll need to invert your roughness map. Game engines read black as smooth and white as rough.

Artist tend to work roughness maps similar to a spec map. White being the bright smooth parts. This is fine as long as you invert your roughness map after your done.

Bek

Roughness is the inverse of glossiness. White values in roughness indicate a rough surface, while darker tones indicate smoother (shinier) surfaces.

As for "how" to make them, you would need to have an accurate idea of what value corresponds to the surface you're trying to re-create.

Two good links:
http://www.marmoset.co/toolbag/learn/pbr-theory
http://www.marmoset.co/toolbag/learn/pbr-practice

Additionally if you examine the scanned materials available in the Quite Suite (dDo) you can get a good idea of some common material types and their corresponding values for gloss, spec, albedo.

JordanN

Ok, so say for example I had a brick. Could I take the base color texture, and in photoshop, play with the hue/saturation modifier till the texture appears very white (because brick has a very rough surface), and that would be my roughness map?

Could this method also be used on all textures?

Kurt Russell Fan Club

No, absolutely not.

Imagine a black and white chessboard that's covered in lacquer to make the whole thing smooth and glossy. Diffuse values for the checkers will be drastically different. Roughness for the checkers will be nearly constant, and shouldn't show any of the chequered pattern at all.

Roughness for lots of materials tends be lower wherever an object gets beaten up. So make it lower on edges and higher in crevices. You can use edge detection bakes and AO/cavity bakes to add some detail to roughness.

Think about what roughness means and what kinds of details need to be added to your texture - oil, fingerprints, dirt, how do they add to basic material roughness? Paint them in and/or use some texture overlays if you like to adjust a base roughness value.

JordanN

Ah man, this sounds more confusing than I thought.

So everything about the roughness texture will have to be created from scratch? I understand not to reuse different roughness values for different materials that don't match up.

Edit: Ok, I'm starting to get it now. The roughness can't be an exact copy of the base color with modified values.

kaptainkernals

I suggest you read both the below link, as well as the encyclopedia 3py0n created (it's taken feedback from many people to get it to where it is)

http://www.polycount.com/forum/showthread.php?t=136390&highlight=pbr

Also, the marmoset ones are some of the best you'll find.

Also linked in 3pyon's thread: http://www.polycount.com/forum/showthread.php?t=135431, an example assest using correct PBR.

This is also all available on the wiki, along with videos and other great tutorials / pages of information

http://wiki.polycount.com/wiki/PBR

grimsonfart

Oh, i think i have missed something here. I thought gloss was practically the same as roughness. As i use CryEngine, there is no specific roughness slow. Does anyone know how to use it in the engine??

Farfarer

They're related, but opposite. Gloss is the inverse of roughness.

In a gloss texture, more white = more glossy (less rough), more black = less glossy (more rough).
In a roughness texture, more white = more rough (less glossy), more black = less rough (more glossy).

JordanN

It was mentioned earlier in this thread that the roughness/microsurface maps needs to take into account scratches, wear and tear, oil, fingerprints etc. Is there a reference guide out there for those values or can I use my own artistic judgement?

I'm use to Unreal Engine 4's workflow so I know, based on 0 to 1, a buff could either look mirror like smooth, very rough, or somewhere inbetween the two.

Farfarer

It's up to you - just remember you're trying to show how rough or smooth it is at a microsurface level.

There are "standard" values for various surface materials, although their accuracy depends on the particular implementation of the PBR system (like http://seblagarde.wordpress.com/2012/04/30/dontnod-specular-and-glossiness-chart/).

It's probably wise to keep those relatively close, but there's a ton of stuff that can change the roughness of a surface that wouldn't match up to the "correct" values. So you've got some leeway to fudge things in, I reckon.