The purpose of our experiments was to investigate the effect of interaxial camera separation on the perceived shape and
viewing comfort of 3D images. Horizontal Image Translation (HIT) and interaxial distance were altered together.
Following Banks et al (2009), our stimuli were simple stereoscopic hinges and we measured the perceived angle as a
function of camera separation. We compared the predictions based on ray tracing with the perceived 3D shape obtained
psychophysically. 40 participants were asked to judge the angles of 250 hinges at different camera separations
(interaxial and HIT linked a 20-100mm; angle range: 50°-130°). Comfort data was obtained using a five point Likert
scale. Stimuli were presented in orthoscopic conditions with screen and observer Field of View (FOVO) matched at 45°.
Our main results are: (1) For the 60mm camera separation, observers perceived a right angle correctly, but at other
camera separations right angles were perceived as larger than 90° (camera separations > 60mm) or smaller than 90°
(camera separations < 60 mm). (2) The observed perceptual deviations from a right angle were smaller than predicted
based on disparity information (ray tracing model) alone. (3) We found an interaction between comfort and camera
separation: only at the 60mm camera separation (e.g. at typical human eye separation) do we find a significant negative
correlation between angle and comfort. All other camera separations, the disparity (angle) has no systematic effect on
comfort. This research is set out to provide a foundation for tolerance limits for comfort and perceptual distortions
brought about by various virtual camera separations.