ACES workflow with MtoA 2020 - Setup & sRGB Textures - Lots of questions.

[kyanetemadi]

Hey everybody.

ACES still is a big questionmark for me and the more I read about it, the more questions come into my mind. This is how I made my setup, based on @Arvid Schneiders recent Youtube Stream (https://www.youtube.com/watch?v=kReV9sUFe6E ). I hope someone can confirm that I am doing it right.

For testing, I am starting with an old scene, with a few sRGB textures, Maya color swatches, utilities like aiNoise and standard, out of the box settings in Maya.

1. I downloaded the color configurations from https://github.com/imageworks/OpenColorIO-Configs and put the aces_1.0.3/config.ocio file into the OCIO Config Path in Mayas Color Management.

2. A warning message appears "All color spaces used in the scene are not defined in the selected transform collection. If you proceed, affected color spaces will not be applied." and I click on "Proceed"

3. In Mayas Color Management Preferences the rendering space switches automatically to "ACES - ACEScg". The view transform switches to "sRGB (ACES)".

4. Under Input Color Space Rules, is set the Input Color Space to "ACES - ACEScg"

6. I set the View Transform of Arnold Render View to "sRGB (ACES)"

7. All my file texture nodes show a red warning "sRGB" color space not found. No color transformation will be applied.

8. I hit render, the image is darker than rendering with the standard settings but I get a broader range, all sRGB textures are washed out. The objects where I only used color swatches and utility nodes are looking more natural and as they should, highlights look sexy now and not blown out anymore. I have the feeling that the overall quality improved a lot but I know that textures need another color space.

9. Thats the point where I started to experiment with the color space settings in the file texture nodes: I chose "Output -sRGB". Probably wrong, but it was one of the few profiles in the dropdown menu that had sRGB in it and I chose to test. The textures in the rendering look right, I also set bump- and roughness maps to "Output - sRGB" and bump and roughness become way, way more stronger. Overall It looks good, but I know something is wrong with the color space settings.

So here are a bunch of questions I have:

- Is the setup from 1-8 right?

- Arvid says in his stream, that all textures need to be converted from sRGB to ACES. I don't have Nuke at hand and don't know how to convert the textures without it. Can I also convert them in Photoshop?

- Can I somehow use the sRGB textures I already have in Maya and use them as they are by choosing a specific color space in the file texture node without conversion to ACES? Maybe there is an Arnold node I can use to do the conversion in Maya without any third party program?

- I had my bump- and roughness maps set to RAW in the old color space settings of the file node. Do I also need to convert those maps to ACES (in Nuke or Photoshop) or is there an equivalent to RAW when working with ACES in MtoA? Can I just use "raw" from the dropdown menu in the file texture node? Do I need RAW anyway in my old scenes?

- Is there a way of switching all color spaces in all the file texure nodes at once? Without touching the nodes, having everything red and not defined in my old scenes, it would be cool to change everything at once.. like with the attribute spreadsheet editor in Maya for example, without changing everything by hand, one by one.

- After Batch Rendering, what is the right setting in Photoshop? I went through two ACES Proof Setups in Photoshop, where "ACEScg ACES Working Space AMPAS S-2014-004" looked very close to the still image in Arnold Render View. Is that a Proof setup I can work with on still image compositing in Photoshop?

Its a longer post and I am a technical noob when it comes to questions like this color space topic. Now that I know that ACEScg exists and that renders instantly look way more "natural" and better than before, I really want to use this right and hope that someone can give me answers to my questions.

Best Regards,
Kyan

[maxtarpini]

TL;DR 🙂 but this may help ...

https://cgrenderdna.blogspot.com/2019/06/updated-acescg-workflow.html

[Anonymous]

Yes I agree with you
Arvid says in his stream, that all textures need to be converted from sRGB to ACES!
1- What if you don't have Nuke or Houdini or fusion for conversion?
2- He did not say how to convert displacement map, normal map, bump map, environment map.. etc..
3- 8bit and 16-32bit has different rules conversion!
4- even in pdf: https://drive.google.com/file/d/1wRjizA0nmL7GE84WaZouthn2s-3bcutN/view
Rule priority default to Utility -sRGB - texture ! witch must be set to ACES-ACEScg

Here are some rules you can use
no need other packages to do conversion

[kyanetemadi]

Hey Rachid. Thats a nice overview and looks very promising! It corresponds with the .pdf from Slava Sych. I never really used the Color Management Preferences window but its a very good hint to create rules for textures. I'll try that out tonight and hope that everything works.

For the Photoshop workflow afterwards: do I get it right that I can use the .icc file that comes with the files provided at GitHub? OpenColorIO-Configs-master\OpenColorIO-Configs-master\aces_1.0.3\baked\photoshop

Would I just load the sRGB for ACEScc as a Color Profile and choose it?

[Anonymous]

You have to download OCIO for Photoshop and exr-io
more about Aces-Photoshop here:
https://acescentral.com/t/aces-photoshop-friendly-workflows/1369

[dave.cookL6ZQU]

I would suggest reimporting the 8 bit textures and see which conversion your OCIO rules apply when you do. Then you will know what to apply to any other legacy textures you have.

The 'sRGB' colour space does not exist by that name in ACES, (so it will always error when you open a scene that contains textures with that transform selected). But you can still access an appropriate transform within Maya: you do not have to explicitly convert every single file to ACES before loading into Maya.

[kyanetemadi]

I think I managed to get it working. I changed all the texture nodes by hand with the aces-rules that @Rachid sent the other day. The renders look very good now, roughness and bump look as I would expect them to look.

RGB textures to Utility-sRGB-texture

Bump & Roughness to Utility-RAW

exr to Utility-Linear-sRGB

I'm unsure about black and white alpha masks though. I would set them to Utility-sRGB-texture, is that right?

[lee_griggs]

More information about ACES can be found here.

[Anonymous]

simple rules:
any texture acting as DATA like bump, displacement, gray scale...ie: no color, must be set to Utility-RAW
Other textures are case dependent

[froszu]

Is it possible to convert to acesCG with maketx from command line ?

[kyanetemadi]

Thank you Lee! I'll have a look.

[kyanetemadi]

Allright, I got you. Thanks for your help!