cryptomatte and Image Sampler

[Adam]

Hello All!

As far as I know, the Cryptomatte Render Element requires the Bucket Image Sampler in order to be rendered properly. However, the Bucket Image Sampler is not available for the Arnold Rendering Engine in 3ds max 2018 - thus I consistently fail to render the passes properly; I constantly end up with black images.

Is there a trick in order to make it work, or am I doing something wrong in the first place?

Any ideas are welcome!

Cheers,

Adam.

[jfriedman7W638 · Accepted solution]

Hi @Adamantios Tegkelidis,

"Bucket Image Sampler" is a VRay thing, not an Arnold thing.

Test your Cryptomattes in Nuke or with another Cryptomatte decoder. When the EXR gets written, the "preview channels" are made black on purpose to save space, as they are deprecated and not used by the decoders.

There is an option on the AOV shader to write the preview channels into EXRs, but I don't recommend it.

[Adam]

Hi @Jonah Friedman

thank you very much for the help. As far as the file format is concerned, I thought that it always has to be EXR; no? In that case, should I save AOV's as jpegs or tiffs?

What Cryptomatte decoder do you recommend? I am using Windows 10 and 3ds max 2018 btw.

Best,

Adam.

[jfriedman7W638]

The one for whichever compositing application you are using. A list is here: https://github.com/Psyop/Cryptomatte#implementations. The Nuke one is the most mature.

Yes, it has to be EXR. You can write another format but it won't be a Cryptomatte, and keying the preview channels with a soft key type thing is not the right way to use these.

[Adam]

Link to cryptomatte decoders: https://github.com/Psyop/Cryptomatte#implementations.

and EXR plugin for photoshop.

Cheers,

A.