Objects as masks
by Brett Thayer on Oct 6, 2008 at 6:40:42 pm
I have a rather complex animation scene and I need to render it in different layers so I can edit them in photoshop from by frame.
In the good old days I'd make a matte texture that was the same as my background then assign that to the objects I didn't want rendered but wanted to use as masks. I'm wondering if there is an easier way to do this will allow me to render just the objects I need visible while using the other object to work as masks?
I only need alpha channels for the visible objects but want the invisible objects to still crop the rendered data..
Re: Objects as masks by Brian Murphy on Oct 6, 2008 at 9:50:06 pm
It sounds like you'd want to render out multipass files. You basically assign a "compositing tag" to each of your objects and give them each a different buffer number in the "Object Buffer" tab. Then in your render settings under "multipass" you will click the "Channels" arrow and click on "Object buffer", referencing as many objects as you have assigned with different buffer numbers. Then set up the way you want them rendered out (Quicktime, bitmap sequence, etc).
I use this for heavy scenes to control the color, brightness and contrast of each object. It will render out an alpha channel for each object to which you have assigned a buffer. You could also use these alpha mattes to "mask out" other things in your scenes as well - hopefully, this is what you're looking for.