Object ID Mask with errors - why?

Hi everyone,

I made an ID mask for the car but on the tail light where the white colour is presented the mask has these errors (black parts) - why?

This is the render with transparent BKG:

The car (all parts) has the pass index of 1 but here U could see the tail lights on the mask:

…any advices? The material was slightly darker before this happens and to be exact when I change it to something different (tried the orange from the other side of the light) the problem is gone so looks like the colour is a problem but why???

 Sincerely, Jan

Noone knows? Really?

PS: Also tried to use Material ID Mask but the problem persists! (ie the material ID mask also has those black issues)

Hi, my guess is that you accidently duplicated the geometry - sellect the problematic lights and move them somewhere else and see if there is no duplicate in the same place.
My second guess is that you have wrong settings of Alpha Threshold. You can find it in RenderLayers settings - under Passes - Alpha Threshold - try to change in in both directions, it might help.

Hi Mara,

YEP, Alpha Threshold set to 0 solves the problem!!! U R THE MAN!!!

 Sincerely, Jan

I am glad I could help :).
Btw. the model looks really good! :slight_smile: