ACES for Texture Painting


(Mohammad Farjamfard) #1

Hi guys, I’ve read all the current topics about the ACES workflow and as amazed by this system as I am confused about what would be the correct transform type for an input sRGB texture for say an Albedo or Diffuse texture mapping?

I am working in ACEScg.
By setting up Maya to work in ACEScg it applies sRGB input transform to sRGB textures automatically and while viewing the render through RRT v1.0 the result is as expected meaning the texture come through naturally like when working in a Linear workflow (removing 2.2 gamma from textures, viewing the result with an sRGB transform etc).

BUT!

In Mari or Nuke, OCIO uses “Utility sRGB” transform type for input 8-bit sRGB images or textures by default and it gives way darker textures!

The solution though is to use “Output sRGB”. But what is happening here? Why all apps are default to use “Utility sRGB” for input 8-bit sRGB images that gives darker textures…

Even if I feed my shaders with physically accurate Albedo values like 0.56 in sRGB, they will appear darker than this value in rendered result which I think its wrong!!!
So then we need to add more light to the scene, or bring up the texture brightness using say a level adjustment in PS for example?!!!

Am I confused or making a mistake here or what?! :confused:


(Mohammad Farjamfard) #2

Ok I think I’ve found the answer, correct me if I am wrong but as I’ve understood, ACES consists of two parts, a color space (ACES) and an especial transform (RRT) which tone maps the information in ACES gamut to be visible correctly on a monitor. So no matter which input color space we are feeding into ACES, the output would appear darker due to the way RRT works and its a correct way of working… (?!)

And off course we use “Utility - RAW” for things like specular or glossiness maps.

Just for the reference, I am using the Foundry Mari software for texture painting 3D assets using its OCIO color management pipeline.


(Mohammad Farjamfard) #3

Excerpt from Autodesk Maya Documentation which describes the behaviors better than anywhere I’ve seen:

“Output-referred images, such as video and sRGB, should have the gamma removed and an inverse tone map applied.”

I’ve found it so clear and concise, for those who might be interested, please visit:
http://help.autodesk.com/view/MAYAUL/2018/ENU/?guid=GUID-780C50BC-A79D-4F81-96B1-C0BA86BC2D95

http://help.autodesk.com/view/MAYAUL/2018/ENU/?guid=GUID-24E4143D-6FD1-4210-B677-3D5EEF3D3F29

Man, it seems simple in the first place, but this system is really confusing for those new to it at the beginning! :crazy_face:

But indeed it does worth it! :sunglasses: