Figure 3.
The geometry of retinal disparity. A subject observes three vertical posts, two of which are at one distance and the third is placed closer to the subject. The situation is represented from an overhead view which shows positions of visual direction from each post for left and right eye views. The images of the posts are represented adjacent to the retina where the distance αR is larger than that of αL. On the right of the figure, various positions in visual space are represented by squares. From the different crossing planes, the visual system has to determine the appropriate coordinates to perceive correct distance.