BUG? Material AND Object Layer need AOV ID for clean mask

[pegot]

Building a composite, I added AOV id’s to my materials but my custom mask pass rendered incorrectly, with all sorts of different values other than straight white. Reflections from lights as well as parts of my material’s label can be seen in the mask.

I then removed the AOV id from the material and attached it to the Object Layer instead. I got the same incorrect mask results. So next I tried adding the AOV id to both the material AND Object Layer. This finally resulted in a clean mask.

Is this expected behavior or a bug?

Behavior occurred in both 2021.1 and 2021.1 XB

MaterialID.png

ObjectLayerID.png

Correct.png

[john_otoy]

Can you attach (or PM me) an orbx scene showing the issue?

[pegot]

Can you attach (or PM me) an orbx scene showing the issue?

Ok I PM'd you the file, along with some additional notes.

Basicaly, it appears as if the issue is being cause by a Volumetric Spotlight.

[abstrax]

This is a limitation: If you have a surface that records a mask in a custom AOV, it can do that only if a path actually reaches that surface. If you place a scattering volume in front of that surface then those samples that scatter in the volume don't reach the surface, effectively hiding the surface, resulting in a mask value less than 1.

If you don't need the scattering effect of the volumetric light, just set the scattering color to black and the mask will 1 again.