Achieving near-correct focus cues in a 3D display using multiple image planes

Focus cues specify inappropriate 3-D scene parameters in conventional displays because the light comes from a single surface, independent of the depth relations in the portrayed scene. This can lead to distortions in perceived depth, as well as discomfort and fatigue due to the differing demands on accommodation and vergence. Here we examine the efficacy of a stereo-display prototype designed to minimize these problems by using multiple image planes to present near-correct focus cues. Each eye's view is the sum of several images presented at different focal distances. Image intensities are assigned based on the dioptric distance of each image plane from the portrayed object, determined along visual lines. The stimulus to accommodation is more consistent with the portrayed depth than with conventional displays, but it still differs from the stimulus in equivalent real scenes. Compared to a normal, fixed-distance display, observers showed improved stereoscopic performance in different psychophysical tasks including speed of fusing stereoscopic images, precision of depth discrimination, and accuracy of perceived depth estimates. The multiple image-planes approach provides a practical solution for some shortcomings of conventional displays.