If you give a computer a 3d world, and a single photgraph, is it possible for a computer to calculate where the photo was taken from - in the long run to automatically map textures onto the walls of a room? Tim

Yes, but only if you are taking pictures of a highly non-regular landscape. For example, If I took a picture of one of the corners of a plain square room, there wouldn''t be any reference points to differentiate it from any other of the corners of that room.