THE PERCEPTION OF DISTANCE IN SIMULATED VISUAL-DISPLAYS - A COMPARISON OF THE EFFECTIVENESS AND ACCURACY OF MULTIPLE DEPTH CUES ACROSS VIEWING DISTANCES

The ability effectively and accurately to simulate distance in virtual and augmented reality systems is a challenge currently facing R&D. To examine this issue, we separately tested each of seven visual depth c ues (relative brightness, relative size, relative height, linear persp ective, foreshortening, texture gradient, and stereopsis) as well as t he condition in which all seven of these cues were present and simulta neously providing distance information in a simulated display. The vie wing distances were 1 and 2 m, In developing simulated displays to con vey distance and depth there are three questions that arise. First, wh ich cues provide effective depth information (so that only a small cha nge in the depth cue results in a perceived change in depth)? Second, which cues provide accurate depth information (so that the perceived d istance of two equidistant objects perceptually matches)? Finally, how does the effectiveness and accuracy of these depth cues change as a f unction of the viewing distance? Ten college-aged subjects were tested with each depth-cue condition at both viewing distances. They were te sted using a method of constant stimuli procedure and a modified Wheat stone stereoscopic display, The perspective cues (linear perspective, foreshortening, and texture gradient) were found to be more effective than other depth cues, while effectiveness of relative brightness was vastly inferior. Moreover, relative brightness, relative height, and r elative size all significantly decreased in effectiveness with an incr ease in viewing distance. The depth cues did not differ in terms of ac curacy at either viewing distance. Finally, some subjects experienced difficulty in rapidly perceiving distance information provided by ster eopsis, but no subjects had difficulty in effectively and accurately p erceiving distance with the perspective information used in our experi ment, A second experiment demonstrated that a previously stereo-anomal ous subject could be trained to perceive stereoscopic depth in a binoc ular display. We conclude that the use of perspective cues in simulate d displays may be more important than the other depth cues tested beca use these cues are the most effective and accurate cues at both viewin g distances, can be easily perceived by all subjects, and can be readi ly incorporated into simpler, less complex displays (e.g., biocular HM Ds) or more complex ones (e.g., binocular or see-through HMDs).