"Our minds use the principle of perspective to provide the third dimension." Totally agree with the author. Actually our minds use a whole set of cues besides

"Our minds use the principle of perspective to provide the third dimension." Totally agree with the author. Actually our minds use a whole set of cues besides perspective to estimate the third dimension and stereopsis (used in "3d" movies) is just one of them. http://en.wikipedia.org/wiki/Depth_perception http://en.wikipedia.org/wiki/Depth_perception