Multipart EXR2 layers / EXR compression

Development Rendering
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Hello,

In multipart EXR that is available in the render graph in 5.6, it states that it supports having different image types and resolutions for each layer. Thing is, as the output resolution, type, sampling and compression settings are all global nodes, we could not find any proper way how to achieve that behaviour. Does the “Multipart” checkbox mean only using EXR2 for now with those layer specific node settings TBD?

Being able to use EXR2 would be significant gain for our pipeline in all areas, be it storage size, load times, transfer speed etc.

One of the things we hoped to have access to was ability to set different compression for each layer. Current UE implementation of DWAA/DWAB compression in EXR does not fall back to ZIP/RLE when storing cryptomatte/Object ID layer as it should by OpenEXR standard in offline renderers.

Using separate files is sometimes an option to some degree, but multilayer/multipart EXR are generally more preferable between our compositors and in our workflow.

Do you think there could be some fix for the compression fallback for crypto, if the per layer settings would be too far off in the future?

Thank you very much!

Tom

2

Steps to Reproduce
Set compression to DWAA on the EXR in MRQ or MRG

Cryptomatter/Object ID layer will be broken by compression instead of falling back to ZIP/RLE

[Image Removed]

3

Hi, this is a known issue with the current implementation of multipart EXRs. If you use lossless compression for the EXRs, multipart should work just fine. (Cryptomatte needs exact values in the data in order to work correctly, so it breaks when compression is introduced). Beyond that, we don’t have additional workarounds or fixes for this at the moment. I hope that helps, though.

4

Thank you for your response.

And would you have at least some rough timeline, when multipart EXR might get the MRG support for multi resolution layer outputs?

Thank you very much!

Tom

5

Hi -- unfortunately, we don’t have an estimate to pass along at the moment.