Compositing | Disjoint Over
Rendering out your shot in layers with hold-out masks can be very useful, but it can be tricky to re-assemble the image in your compositing application of choice. This video will show you how it is done.
Update:
I case some of you are wondering why there still is some purple/green showing through on the white pieces on the right, that’s because of a less then ideal shader choice on my part. I used a transparent plastic material for the white pieces, so there is some actual transparency on those spots. The good news is the disjoint over preserves transparencies as you can clearly see.