Ambient occlusion interior

[mwheeler]

how would you go about making an ambient occlusion pass with the camera inside a cube? I am doing an interior rendering of a room without any windows and my attempts at AO passes have been black. I could cut a whole in the wall behind the camera to let the environment light in but was curious if there was another way to pull this off.

[rspierenburg]

You could make a double sided material that is Transparent on the back-face and opaque on the front-face. This will allow light to pass through without being to see out. I've done something similar (actually the reverse) for the ceilings of units so that I could get a sense of lighting by windows by look at the unit from above.