THE PROBLEM of space perception is an old and important problem in visual physiology. It is assumed that there is some relationship between the world we live in and our visual sensations. But it is known that there is not a one-to-one correspondence between physical stimuli and visual sensation. One unit of physical measurement does not cause one unit of perception. Our sensations do not change directly with the physical change of the stimuli causing them. Many inconsistencies and paradoxes arise when we try to correlate our perceptions with the physical configuration of the stimuli. Until recently it seemed such a correlation was impossible. The essence of Luneburg's "Mathematical Analysis of Binocular Vision"1 is that there exists such a basic correlation limited to the assignment of apparent size to line elements and that if this concept proves true much valuable information regarding our space perceptions may be derived mathematically