Houdini 20 HtoA OCIO/ACES config troubleshooting

[brianswarthout]

Hello,

I'm having trouble getting ACES/OCIO to work properly in Houdini 20 when rending with Arnold. I have followed the workflow outlined in the Autodesk documentation and some of the options available do not align with what I'm seeing in Houdini and when compositing in After Effects.

First, I've gone ahead and pointed by OCIO package to reference the ocio.config that ships with Arnold:
Houdini OCIO Settings

Following along with the ACES workflow documentation, I'm attempting to change the color space settings in the Solaris Render Product Node and the Render Settings Node but oddly enough "ACES" is not an available option for the "Output color family" in the Render Product Node or the "Rendering Color Family" in the Render Settings Node. Instead, I have the option of "Scene-linear" or "Utility." Selecting "Scene-linear" allows me to choose "ACEScg" in the adjacent drop-down on both nodes.

Render Setting Node Properties

Render Product Node Properties

Furthermore, in the Solaris render view, I have different options in the OCIO display and view options than are shown in the ACES workflow documentation.

OCIO Display Options

OCIO view options

Upon rendering, I have those same options in Mplay. Then, when I bring the EXR into After effects for rendering, the colors are over-saturated compared to the soalris render view and the Mplay view. The color settings in After effects are:

Color Engine: OCIO

OCIO Configuration:  Aces 1.3 CG v1.0

Bit Depth: 32 bits per channel (float)

Working color space: scene_linear:ACEScg
Display color space: sRGB - Display/ACES 1.0 - SDR Video

Does anyone know why I'm not seeing the color spaces in the Render Product and Render Settings nodes? Is the saturation shift in After Effects due to a OCIO setting mismatch?

Any help would be greatly appreciated.

Thanks,

- Brian

[Stephen.Blair]

It's a bit strange that the OCIO Editor says you are using the Houdini config.ocio. But everything else looks like the Arnold config.

What ACES workflow documentation? Houdini or Arnold (the Arnold doc is for non-Solaris, and the Arnold ROP > Output screenshot needs to be upated).

The Arnold ocio is 2.0, the After Effects is 1.3

[brianswarthout · Accepted solution]

Thanks for your reply @Stephen.Blair. I was following the Autodesk ACES workflow documentation. Good to know it does not apply to Solaris. Is there ACES workflow documentation that does apply to Solaris available?

I too found it odd that the path to the ocio.config still pointed to the Houdini config although the fie handeling was updated to reflect the Arnold settings.

I ended up achieving ACES color consistency between Solaris/Arnold and After Effects by doing the following:
1. Reset Houdini's OCIO settings to factory default (in Houdini OCIO Editor).

2. Added OCIO file handling settings for .tx to covert to "Raw" (in Houdini OCIO Editor).

3. Changed the .exr OCIO settings to convert to "ACEScg" (in Houdini OCIO Editor).

4. Changed the Render Working Space to "ACEScg" (in Houdini OCIO Editor).

5. Changed View Transform to "ACES 1.0 - SDR Video (in Houdini OCIO Editor).

6. Exported the config from Houdini's ICO Editor and am using that in After Effects.

I'll keep this thread updated if I run into any further issues.

[am_wilkins]

Nice to see some conversations around this!

Have you perhaps noticed the Solaris "Render Gallery" doesn't match what you see in the viewport/scene while rendering with "ACES 1.0 - SDR Video" as the view transform?

By "doesn't match" I mean mainly quite a bit brighter by comparison. Almost seems like the render gallery isn't using the same transform.

-
amwilkins

[brianswarthout]

I have noticed that the "Render Gallery" color does differ from the Solaris viewport along with Mplay. Very odd indeed.

[peterDTE7K]

I have same colors in Solaris viewport, mplay and render gallery. Render gallery thumbnails' colors are off but this is not a big issue. I am using default arnold OCIO config from htoa set up via houdini.env file.

I noticed that the OCIO 2.0 that ships with Arnold is different from custom OCIO config 1.2 which I've been using previously.

V2.0 is slightly darker, there is more contrast and also higher saturation. I think I like the 2.0 a bit more.