What is the best CryptoMatte workflow?

[elivnA]

Hello,

We're getting onboard the whole OpenEXR/CryptoMatte workflow to streamline everything, but I still have some questions.

What is the best way to store the EXR file so that Photoshop can open all the CM elements? So far I've not been able to recover the stored CM elements from either the default 3dsmax file output, or the "save separate channels" function in the V-Ray > Frame buffer tab.
The only way I managed to do it is either manually from the VFB itself using the "save to single file" function, or storing to VRIMG and converting to EXR. Are these the only ways to get to the CM elements?

[hermit.crab]

Cryptomatte requires the Bucket image sampler and output as multi-channel EXR to work. You can save from either the "V-Ray raw image file" output or from the VFB with the "Save to single file" option. You can read more about the element in the technical documentation.

[Buck]

As far as general work flow, what I generally do for animated sequences (comping in Nuke) is render out a separate "utility" pass, with all my embedded mattes, cryptos, and whatever else. I keep them separate from the main beauty render mostly because having cryptos and all the other passes can make the file sizes a good bit larger. So if all I'm doing is updating lighting or shaders, I don't need to re-render all those other passes. Only re-render them when any geometry changes or animation changes happen.

Cryptomattes need to be 32 bit in order to work, it's possible that exporting them from the frame buffer is not keeping them 32 bit.

[hermit.crab]

Cryptomattes need to be 32 bit in order to work, it's possible that exporting them from the frame buffer is not keeping them 32 bit.

The Cryptomatte layers are saved as forced 32-bit color depth, both through the Frame buffer options and the VFB.

[elivnA]

Alright, thanks for the replies. I knew that the bucket image sampler is required for CM, only I couldn't find a way (other than VRIMG or save directly from VFB) to store them.I will use VRIMG from now on, it's a small step after all, I suppose.

[Buck]

As far as general work flow, what I generally do for animated sequences (comping in Nuke) is render out a separate "utility" pass, with all my embedded mattes, cryptos, and whatever else. I keep them separate from the main beauty render mostly because having cryptos and all the other passes can make the file sizes a good bit larger. So if all I'm doing is updating lighting or shaders, I don't need to re-render all those other passes. Only re-render them when any geometry changes or animation changes happen.

Cryptomattes need to be 32 bit in order to work, it's possible that exporting them from the frame buffer is not keeping them 32 bit.

Good to know, thanks! I wasn't sure, as I rarely save out of the framebuffer while working

[Jonish]

EDIT: Sorry, posted in a wrong category, not related to 3ds max.