Rendering characters separately from environment in arnold

[miccetro]

Hi everyone, I seeking workflow tips to render characters separately from the environment but still have all the interactions such as reflections, shadows and so forth in both layers. Any tips and ideas would be much appreciated as I'm working on a project which would benefit greatly from this technique in comp. Thanks in advance.

[Juraj]

Hi,
if you want to do such thing you need to set up separate render layers with different Arnold ROPs. In environment layer set your environment geometry into Force Objects and in Phantom Objects select your character. Then do the opposite thing in character layer - force is character geo and environment in phantom objects. 

Check in Arnold's documentation Phantom and Matte objects.

That way will require you to render the scene two times which migh not be very efficient.

If you just need masks for your character, you can set up custom AOV with masks for objects which you can use in compositing. You can also check Psyop's Cryptomatte which is well implemented in alShaders and in Nuke. I think that this Crypyomatte will give you greatest flexibility.

[miccetro]

Thanks much for the info @Juraj that's very helpful.