GIT-GVU-94-25

Relevant Cues for the Visual Perception of Depth: Is Where You See it Where it is?

R. Troy Surdick
Elizabeth T. Davis
Robert A. King
Gregory M. Corso
Alexander Shapiro
Larry F. Hodges
Kelly Elliot

We tested seven visual depth cues (relative brightness, relative size, relative height, linear perspective, foreshortening, texture gradient, and stereopsis) at viewing distances of one and two meters to answer two questions. First, which cues provide effective depth information (i.e., only a small change in the depth cue results in a noticeable change in perceived depth). Second, how does the effectiveness of these depth cues change as a function of the viewing distance? Six college-aged subjects were tested with each depth cue at both viewing distances. They were tested using a method of constant stimuli procedure and a modified Wheatstone stereoscopic display. Accuracies for perceptual match settings for all cues were very high (mean constant errors were near zero), and no cues were significantly more or less accurate than any others. Effectiveness of the perspective cues (linear perspective, foreshortening, and texture gradient) was superior to that of other depth cues, while effectiveness of relative brightness was vastly inferior. Moreover, steropsis, among the more effective cues at one meter, was significantly less so at two meters. These results have theoretical implications for models of human spatial perception and practical implications for the design and development of 3D virtual environments.

Visual perception, depth cues, viewing distance, Wheatstone stereoscopic display, 3D virtual environments

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