ACEScg workflow and EXR maps

Question

Hi everyone,

I have heard that, in VFX, textures are used mostly as 16bit EXRs. I have done some research and understand why this is the case, and this information is very useful to me, especially since I am transitioning to an ACEScg workflow in Substance Painter.

My questions are:

This question is mostly out of curiosity. Substance Painter only exports 32-bit EXRs. I understand that some people convert the exported maps into 16-bit EXRs separately – is this a common thing to do for those working with Substance Painter?

Are all PBR maps supposed to be 16-bit EXRs?

BaseColor/Diffuse (and all other color maps) make sense to have a higher bit-depth, since I am working in ACEScg and I want to export these maps in ACEScg color space.

For Height and Normal maps, I noticed the higher difference in quality when rendering using EXR bitmaps, instead of 16-bit pngs, so that convinced me.

What about the rest of the maps?

Thank you.

sharktacos · Accepted Answer

Substance Painter actually writes EXR files in 16-bit half with PIZ lossless compression. You can see this if you look at the metadata for the EXR in Nuke.

I always save height (bump) maps as EXR from SP as there is a loss in quality if they are saved in 8-bit.

For diffuse maps it depends on the color space. If it's ACEScg then yes it needs to be in EXR since it will be scene-linear. However, if you save it as Utility-sRGB-texture then it can be an 8-bit JPG or PNG. You just need to read it into your rendering program (Maya for example) with the same input transform.

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