In 1934, American ophthalmologist Adelbert Ames, Jr. created this optical illusion. Two people with the same height and apparently at the same distance from the observer appear to be out of proportion. You can rotate, translate, and modify the perspective to understand the actual shape of the room.
 Wikipedia. "Ames Room." (Jan 26, 2012) en.wikipedia.org/wiki/Ames_room.