Looking for an ACES example setup

[vlado]

Hello,


I'm implementing native ACEScg support for V-Ray and some of the V-Ray components (i.e. bitmaps, VRaySun, VRaySky, temperature colors etc) and I need some scenes to verify the correctness of the implementation. Such a set up usually required an abundance of VRayOCIO textures before - if anyone can share such a set up, it will be extremely helpful.

Best regards,
Vlado

[GoodbyeKansas]

Digging this up as we are looking at it again now. Did this make it into VRay Next for Maya? Is the recommended workflow documented somewhere?

* Convert all textures and input materials to correct space
* Use correct ocio config for viewing

But I also read about some setting for changing how VRay works internally with some objects.

-- Erik

[corestudio]

I'd love to hear about this as well

[jasonhuang1115]

bump this up to follow and learn if there is any news in this regard. If this is sorted, can we have an example setup in Vray Next Maya documentation?

[stevejjd]

Hi Vlado,

Is there any news on the ACEScg support for Vray?

Also is there any guide on how to set up the color pipeline for V-Ray

Thanks
Steve

[moshev]

Hello,

We are currently working on support for ACEScg as a rendering colour space and as a texture colour space, so you could set your rendering colour space to ACEScg and get automatic conversions for sRGB, Rec.709, and ACEScg textures. Full support for every colour space is not planned as a native feature at this time, so if you want conversion from/to anything outside sRGB/Rec.709/ACEScg you'll need to use the OCIO node. Currently we do not take into account Maya's colour management settings. So whatever conversion you set on the OCIO node is what will be performed.

If you don't mind the complexity, you can right now pre-convert your textures to ACEScg using e.g. OpenImageIO's oiiotool and then set them to use "ACEScg" colour space in Maya, which will default to linear colour space for V-Ray. Since we won't be doing any colour conversions you'll be effectively rendering in ACEScg colour space. If you also set your rendering colour space to ACEScg from Maya's colour management options, all colour pickers will output ACEScg values and will work correctly.

There is also an undocumented option in vraySettings - vraySettings.rgbColorSpace, which can be 1 (Rec709, default) or 2 (ACEScg). This only affects Sun/Sky and colour controls with "Temperature" setting.

About the OCIO node, if you don't want to pre-convert your textures and instead want to use OCIO, the correct input colour space for sRGB textures is "Utility - sRGB - Texture", and for Rec.709 (aka linear sRGB) it's "Utility - Linear - sRGB".
Pre-converting your textures will result in faster render times than using the OCIO node.

In short, to use ACEScg today:
1. Enable Maya's colour management and set your rendering colour space to ACEScg. You do not need to use ocio config in Maya.
2a. Grab the ACES OCIO config and pass each of your textures through a V-Ray OCIO node using the correct input colour space and "ACEScg" output colour space; or
2b. Pre-convert all your textures to ACEScg (other than normal maps, bump maps, etc. of course) with oiiotool.
3. If you have sun/sky or lamps using temperature colour control, run "setAttr vraySettings.rgbColorSpace 2" from the MEL console. The setting is saved in the scene, so it's a one-time setup per scene.
4. Render in the Maya render view, or use VFB's OCIO colour correction.

Note, ACES does support a much wider colour gamut than sRGB, but if your input data is not already in ACEScg, you won't see much of a difference. There is very slight difference in the saturation of GI resulting from multiple bounces hitting the same material, mostly for the red part of the spectrum. A texture converted from sRGB to ACEScg, then illuminated by a 6500k light, will look exactly the same when converted to display colour space, regardless if it's an sRGB, or a DCI-P3 monitor, or a movie projector, without the intermediate ACEScg step. ACEScg really makes sense if you're working with textures that already have colours outside Rec.709 range.

[TheScope]

Hi,
thanks for the good tutorial.

I have one question:

Currently we do not take into account Maya's colour management settings. So whatever conversion you set on the OCIO node is what will be performed.

Does this mean that the color space attribute of file nodes will be ignored by V-Ray?

Cheers, Florian

[moshev]

The color space attribute is always taken into account - V-Ray tries to match the name to one of our internal available gamma corrections, and if that fails, falls back to linear. Meaning, up to and including V-Ray 4, the following values are supported: "linear" (e.g. "linear sRGB", or "scene-linear Rec.709"), "sRGB", "gamma 2.2", and "gamma 2.4" - corresponding respectively to no gamma correction, sRGB conversion, gamma 2.2, and gamma 2.4. You can also use the extra V-Ray attributes to force a specific correction (extra attributes->vray in the attribute editor).

After linearising the color, no farther conversions are done, so the more correct term for what V-Ray does is "transfer function". In order to perform actual color conversion, you have to connect the texture through an intermediary V-Ray OCIO node - this is only needed if the texture's color space and the renderer's color space do not match.

For V-Ray 5, we want to have full native support of ACEScg for textures and as a rendering color space, with automatic conversion of textures to the rendering color space, so that for the majority of cases you'll just set your preferences in Maya and it will just work. We'll have a guide on how to make use of color conversions once V-Ray 5 is ready.

[TheScope]

Thanks for the explanation. When can we expect Vray 5 nightlies?

[jasonhuang1115]

Wait....did I just read a comment about what's coming in Vray 5?

[vlado]

Thanks for the explanation. When can we expect Vray 5 nightlies?

There's nothing else that we can share right now

Best regards,
Vlado