Perception of stereo at different vergence distances: Implications for realism

Stereoscopic 3-Dimensional (S3D) technology has recently received new considerations for two main reasons: the growing attractiveness in rendering depth for media entertainment, and the advance in 3D display technologies which now broadly dominates the use of anaglyphs. The counterpart of this interest is the list of to-be-solved problems that interfere with the spectators´ quality of experience. One aspect that has received little attention is the deterioration of 3D perception with changing vergence. Two recent studies have shown that changing the vergence distance through binocular disparities affected the perception of 3D shape in such a way that objects displayed behind the screen (with uncrossed disparities) appeared flattened while objects displayed in front of the screen plane (with crossed disparities) were perceived elongated in depth [1][2]. In this study, we investigate the perception of 3D shape of random-dot stereograms at several vergence distances displayed with crossed disparities and then discuss our results according to a model of focus and vergence signals combination for scaling distance in 3D estimation. The implications of our results are discussed in the context of rendering correct S3D content.