Perception of terrain drop-offs as a function of L-R viewpoint separation in stereoscopic video

Military missions often require drivers to maneuver across hazardous, off-road terrain using visual displays rather than direct vision. When soldiers use 2D displays, significantly more mobility errors occur than when soldiers use 3D displays that provide a stereoscopic view of the terrain. The purposes of the present experiment were to quantify the visual forewarning of a drop-off provided by a stereoscopic 3D display compared to a 2D display, and to measure the potential of increased camera separation (i.e., hyperstereo) for enhancing the benefit of 3D for the detection of terrain drop-offs. This experiment consisted of four viewing conditions: OX (the 2D condition), 1X (stereo with the normal interpupillary distance [IPD] between the viewpoints provided to the two eyes), 2X (stereo with twice the normal MID), and 3X (stereo with three times the normal IPD). Thirty-two participants viewed 80 video clips, each clip depicting an approach to a terrain drop-off as would be seen in a daytime driving situation. As soon as the drop-off became apparent, he or she pressed a brake pedal. As expected, the average detection time for drop-offs viewed with 1X (stereo display) was significantly better than when drop-offs were viewed with the 0X (2D) display. The failure to observe further improvements in task performance with 2X and 3X 1PD suggests follow-on research to determine whether these unexpected hyperstereo results may be attributable to adverse side effects of hyperstereo: increased mismatch between accommodation and convergence, the minification effect, and increased stereoscopic "frame violation."