From: The World In Your Head by Steven Lehar
Fig. 2.1 (A) The perceptual representation of a man walking down a long straight road. The sides of the road are perceived to be parallel and equidistant throughout their length, yet at the same time they are perceived to converge to a point both up ahead and behind, and that point is perceived at a distance that is less than infinite. This peculiar violation of Euclidean geometry is perhaps the strongest evidence for the internal nature of the perceived world, for it shows evidence of the perspective projection due to the optics of the eye, out in the world around us, although in a unique form. (B) A peculiar property of this warped representation is that its two-dimensional projection is identical to the two-dimensional perspective projection of the corresponding Euclidean space that it represents.