Assigning Multimatte Object ID to scatter objects

[churp]

Hi all, I have two interior and two exterior scenes to be rendered for a project I’m working on. The colour balance between the trees and grasses in my model is off (trees too blue, grasses to brown) so I had set up cryptomattes for the exterior renderings to have them meet in the middle. This doesn’t work in the interior scenes as the exterior vegetation can’t be selected on cryptomatte through the glass. I was able to set up Multimatte and my glass materials so that the trees can be selected through the glass, but this doesn’t work for the grasses which have been scattered across a few ground surfaces. Since I can’t select scatter guest objects I am unable to assign a V-Ray object ID within the Sketchup viewport. I’ve tried assigning the ID at a few levels and it hasn’t been able to make the grasses show up on the Multimatte render element.

Any advice appreciated, cheers!

[eric-s]

Have you considered two render passes, one with your glass Tag/entities on and one with them off? If the render time is too long for two passes will a render region for just the window area work? If I read your post correctly, you’re just looking for a Material ID for the Scattered objects so you can select and color correct in Post-Processing?

Material Random ID with Glass on:

With Glass off.

[churp]

That thought had crossed my mind…and since I’m not planning on changing the camera view or any of the landscape elements i could render it with a lower quality/high noise threshold for the glass-hidden version just to get the matte so it wouldn’t take much time.

Boss/client want some extreme quality and size on these images so i’d prefer to not do so many versions if I can avoid it.