I am trying to render a scene and need it to clip out my characters in the alpha channel when they walk behind objects in the scene. I have been told this is what I need to do but cannot work it out.

"You will need to Turn the church model into a black
hole matte object so it correctly clips the characters out in the alpha channel and I will also need a
separate shadow pass for your people as well."

Any help with this is much appreciated.

Thanks,

Leon