Working in Aces colorspace

[xteeejx]

Hello,

We've recently begun testing the Aces Colorspace for all of our compositing and finishing. I'm curious, what's the prefered way of dealing with Aces and vray? Is there one?

Simply lighting and rendering scene linear and converting from there? It seems like it would be helpful to convert plates to Aces and light to match those plates. Maybe I'm thinking about it wrong?

Thanks!
-TJ

[vlado]

This depends entirely on you and which color space you want to render in. You have two options. One is to render in linear sRGB - i.e. your inputs like textures and colors will be sRGB (potentially linearized if they are stored in 8-bit) and your output will be linear sRGB. Then you can convert the result to ACES as a post-processing step. Here by "linear sRGB" I mean the sRGB color space without the gamma correction. If you have any inputs that are in ACES color space, you can use the VRayOCIO texture to convert them to linear sRGB for rendering.

The other option is to render in ACEScg color space. Note that ACES itself is not a physical color space and was not specifically designed for rendering. The ACEScg color space on the other hand is designed specifically for rendering (see "ACEScg – A Working Space for CGI Render and Compositing"). Which means that if you have any input to the renderer (textures, colors) given in ACES color space, you will have to transform them to ACEScg. If you have any sRGB inputs, they will need to be transformed to ACEScg. You can either do this in a preprocessing step, or using the VRayOCIO texture map (although this is considerably slower) if you have suitable OpenColorIO configurations. The output of the renderer will also be in ACEScg and will need to be converted to ACES before use. Note that in this case, any spectral values in V-Ray (the sun and sky color, "temperature" modes for lights and textures, dispersion results) will be invalid as they are based on the linear sRGB color space.

I hope this helps - let me know if you have any questions.

Best regards,
Vlado