I FOUND IT!
This is the method used to make those awesome psychedelic bumps on Adult Swim! It's called tilt-shift photography. Apparently it results from misalignment of the front lens of a camera, resulting in a gradient of focus. I'm not sure what that means, exactly, but I think I can see why I made the assumption that the scenes in said bumps were modeled.
Some people think that learning how something was done, getting a behind-the-scenes look at something ruins their perception of it. In this case, not for me. Now I know that anything I take a picture of can be modeled-even if only in a photograph.
A lovely gallery of this sort of work can be found here. Even though it's digital manipulation used on some of these images, I still can't get over how powerful they are, as a total experience. Understand that we're excluding their music from this discussion.