The Neural Control of Vision
L. The Processing of Depth

Interactions between depth cues provided with stereopsis and with shading:

Figures 61A-C (this and next two pages) provide three examples of interaction between stereopsis and shading. Each pair (A, B, C) should first be viewed directly and then, if available, through a stereoscope by fusing the pair. Some viewers may be able to fuse each pair by staring at them without the stereosope. When viewed directly, in A the bottom figure is seen as protruding and the other figures as receding. When the two images are fused the effect is enhanced because the disparity cues provided are in harmony with the shading cues.