Perception of absolute and relative distances in stereoscopic image

In 3-D movies and virtual reality and augmented reality systems, stereoscopic images are used to improve perceptions of realism and depth. The distance (depth) that we perceive can be classified into absolute distance, which is the distance between the observer and the objects, and relative distance, which is the distance between the objects. It is known that in the real environment these two distances are independent. Previous studies have reported that we underestimate or overestimate the absolute distance in stereoscopic images under some circumstances. We examined perceptions of both absolute and relative distances in stereoscopic images to investigate the depth perception of virtual objects. The results of the experiments showed that (1) the perceived absolute distance from the observer to images in front of the screen was nearly accurate and that to images farther behind the screen was underestimated; (2) this underestimation tendency increased in short viewing distances; and (3) the relative distance from the screen to images in front of the screen was overestimated, whereas that to images farther behind the screen was underestimated.