I am working with an image as the media. So when I create a Quad, I see it large in the output view. I want to be able to map the corners of that quad to a much smaller space, BUT WITHOUT affecting the perspective, scale, or appearance at all of the output view. I would call this TRIMMING. Can you TRIM an output quad--that is, map it without altering the scale or perspective?
For example, let's say that a face closeup quad occupies the entire projection area. Can you trim(map) the quad down to eye without changing the size of the eye, leaving nothing but the eye?