Cryptomatte: Layer selection not working on .exr inside Nuke

[tim.art]

Hello,

This issue references one that has been posted on the Psyop page plugin right there: https://github.com/Psyop/Cryptomatte/issues/110

It seems that Arnold doesn't write the data the right way to be recognizable inside Nuke, the "layer selection" can't be picked or changed, "merge AOVs" is on too and the EXR has been rendered with the render sequence.

For the environment: Maya 2018.6, Nuke 11.3v4 (May 2019), Arnold 3.2.1 (May 2019)

Also, render an EXR through the Arnold Renderview make the cryptomatte impossible to be recognizable as well in Nuke: https://answers.arnoldrenderer.com/questions/1317/cryptomatte-renderview.html

[Stephen.Blair]

Saving from the Arnold Render View is not the same as rendering directly to file with Arnold. That won't work.

You'll need to provide more information (such as what versions you use) and a test scene. The cryptomatte exrs I rendered out all have the required metadata

[hitecom8172]

Lol you never save from the Arnold renderview. Never ever do that it destroys render quality. Always hit render in Maya. That's the most probable cause why cryptomatte won't work ....

[tim.art]

Hello Stephen, thanks for your response

I do have a scene but it's a bit private, do you have a mail or another way I can share my scene?

I guess saving from the Arnold Renderview isn't the same than use the render sequence maya tool, but since it's not indicated properly that cryptomatte won't work with the Arnold Renderview, a lot of users aren't informed and still render through the Arnold Renderview thinking it'll work properly and then struggling with the fact it's actually not working.

We were talking about that in the 3D/CGI group on FB, some users also wondered why it does not work.

For the versions information, as I said in my original post:

Maya 2018.6, Nuke 11.3v4 (May 2019), Arnold 3.2.1 (May 2019) with 5.3.0.1 core

Feel free to ask any other information.

Thanks for your help!

[tim.art]

Hi Stephen,

Any response from your side?

[Stephen.Blair]

Saving from the Arnold RenderView won't work. You have to use an EXR written to disk by the Arnold EXR driver, which means you have to use batch render, render sequence, or render current frame.

I can't reproduce any problems with EXRs written to disk by the Arnold EXR driver.

[claire.chaisnal]

Hello,

I know it has been a long time but as I had the same problem twice, in different versions of Arnold / Nuke, I feel like people could be interested in the solution we found. 

For us, it was just a case to check in arnold : select AOV node (crypto_object) > tab "_aov_crypto" (depends how you name it) > check the "preview in Exr"

and that's it. 

Hope it will help