(Resolved) [HOU-3957] Using Aces 1.3 with OCIO v2.1 profile in V-ray for Houdini.

[ad_rietvelt]

Hi,

We are using the studio-config-v1.0.0_aces-v1.3_ocio-v2.1 configuration inside Nuke. We want to set this up for Houdini (V-ray) as well to have the same version in all our software. But we can't get it working:

• When pointing the OCIO env. variable to this configuration, the 'in' and 'out' colorspace drop down menus in the Vray imagefile node are empty. See attachment.
• When using the OCIO-transform node (no V-ray node), I do see all the colorspaces from the config. See attachment.
• When using the original OCIO ACES 1.2 config (https://github.com/colour-science/Op...aster/aces_1.2), it is working how I would expect it.

Does V-ray not support OCIO v2.1 or am I missing something here?

Looking forward to some help in the right direction. Thnx.

[Gosho.Genchev]

Hey ad_rietvelt ,

This is the first time I see this being brought up. We'll investigate and I'll get back to you ASAP.

Best regards!

[flat]

I also pointed out the same documentation issue.
Chaos looking at forums?

https://forums.chaos.com/forum/docum...rial-confusion

[Gosho.Genchev]

Hey flat ,

My apologies, I've missed that somehow, apparently other colleagues as well. We're looking into this!

Best regards!

[ad_rietvelt]

Hey ad_rietvelt ,

This is the first time I see this being brought up. We'll investigate and I'll get back to you ASAP.

Best regards!

Thanks Gosho.Genchev. If you need any more info from my side, please let me know.
In this version of OCIO they do not rely on LUT's anymore. The ACES Studio Config leverages the high quality ACES implementation built into OCIO itself and so requires no external LUT files. Maybe V-ray is still expecting those? Just a quick wild guess.

[Jim Meston]

I was going to get round to bringing this up. OCIO v2 and up are computed analytically so the V-Ray texOCIO node would need to be able to read the matrix transforms from the ocio.config text file.

Also I don't know if this has been mentioned but the vray image file node ignores the config file in favour of the environment variable. This doesn't really matter because 99.9% of people will never be trying to hotswap OCIO configs.

I think (and correct me if I am wrong) we should be able to bypass the old method of using explicit OCIO transform nodes and the OCIO tab in the image file node, with the newer Transfer Function and RGB primaries settings. But it looks like the RGB primaries on the image file node isn't working as expected.

[Jim Meston]

So these should be equivalent... Or am I misunderstanding something here?

[ad_rietvelt]

I was going to get round to bringing this up. OCIO v2 and up are computed analytically so the V-Ray texOCIO node would need to be able to read the matrix transforms from the ocio.config text file.

The V-Ray textOCIO node is also empty when loading the studio-config-v1.0.0_aces-v1.3_ocio-v2.1 configuration (see screenshot).

We load the OCIO config with an env. var called OCIO, that is pointing to the location of the studio-config-v1.0.0_aces-v1.3_ocio-v2.1.ocio file. That should just work right?

[Jim Meston]

[edit] some text removed as potentially confusing.

...........................

Also to add, even if you want to run and ENV var you can do a floating environment variable by instancing it in a batch file or cmd file and running it as a shortcut.

For example this script in a text file, renamed to *.bat and then run will set up the ROP the VFB and the OCIO environment variables.
I have 3 houdini shortcuts to quickly run with and without OCIO and versions etc for testing this kind of thing.

SET VFH_RGB_COLOR_SPACE=1
SET VRAY_VFB_OCIO=1
SET VRAY_VFB_OCIO_INPUT_COLORSPACE=ACEScg
SET VRAY_VFB_OCIO_DISPLAY_DEVICE=sRGB
SET VRAY_VFB_OCIO_VIEW_TRANSFORM="ACES 1.0 - SDR Video"
SET OCIO=C:\OpenColorIO\aces_1.3_CG\config.ocio
START "" "C:\Program Files\Side Effects Software\Houdini 19.5.673\bin\houdini.exe"

[tsvetomira.girginova]

Dear all, hello.

Thank you for the interesting topic.
Some details should be implemented to provide full support for aces-v1.3_ocio-v2.1 - that's why you are not seeing the options in the dropdown (compared to aces-v1.2).
In the current moment we are not able to provide particular time for fulfilling this.

Best regards,
TS

[Jim Meston]

Dear all, hello.

Thank you for the interesting topic.
Some details should be implemented to provide full support for aces-v1.3_ocio-v2.1 - that's why you are not seeing the options in the dropdown (compared to aces-v1.2).
In the current moment we are not able to provide particular time for fulfilling this.

Best regards,
TS

Thank you for the update.

It is worth noting that the vops and vex functions in Houdini work with the inbuilt ocio config for colorspace transforms based of OCIO2 packaged config.
Moving forward Houdini will continue to have a version of the cg or studio config as standard without the need for external config files.
So... not sure how V-Ray devs work aligned to other DCC's but using the inbuilt Houdini functions which directly access either the environment OCIO config or the fallback config you can just use functions like this ...
Cd = ocio_transform("Input - Generic - sRGB - Texture", "ACEScg", vec);
Just a thought...

Anyone else wanting or needing to be on v1.3 (not sure why it would be urgent) can still use COPs vop filter to do image color transforms and just reference that in the V-Ray file image node.
In this way we are using whatever config we want, even just the inbuilt one in Houdini... (we could run Vray without an environment OCIO and still render faithfully in ACES 1.3).







............

Also don't get caught out with ACES/OCIO version changes giving different names.
For example...

Input - Generic - sRGB - Texture
sRGB - Texture
Utility - sRGB - Texture

All of these are the same thing, but just named differently in different ACES versions.
In my experience they all work regardless of the dropdown name.

[tsvetomira.girginova]

Dear all, hello.

When using the mentioned config, the Color Space Parameters In / Out drop-down options in V-Ray TexOCIO and in V-Ray MetaImageFile (OCIO tab) are now visible with our latest nightly builds: https://nightlies.chaos.com/main#/vray6houdini/nightly
Feel free to install and test on your side too.

[Jim Meston]

Dear all, hello.

When using the mentioned config, the Color Space Parameters In / Out drop-down options in V-Ray TexOCIO and in V-Ray MetaImageFile (OCIO tab) are now visible with our latest nightly builds: https://nightlies.chaos.com/main#/vray6houdini/nightly
Feel free to install and test on your side too.

This is not working for aces 1.3 configs.

The ocio config file/environment parms are not working correctly. Under no circumstances can you load a config through the file parm.

The only thing that works is aces1.2 environment.

I am on holiday now so won't reply for a while. But I don't think this situation is urgent as....

"ACES 1.3 is a “minor” system release. This means the update does not change the Reference Rendering Transform (RRT) or modify the existing core transforms beyond addressing reported bugs and/or inconsequential formatting/whitespace changes."