A basic task in the construction and use of a stereoscopic camera and display system is the alignment of the left and right images appropriately–a task generally referred to as camera convergence. Convergence of the real or virtual stereoscopic cameras can shift the range of portrayed depth to improve visual comfort, can adjust the disparity of targets to bring them nearer to the screen and reduce accommodation-vergence conflict, or can bring objects of interest into the binocular field of view. Although camera convergence is acknowledged as a useful function, there has been considerable debate over the transformation required. It is well known that rotational camera convergence or "toe-in" distorts the images in the two cameras producing patterns of horizontal and vertical disparities that can cause problems with fusion of the stereoscopic imagery. Behaviorally, similar retinal vertical disparity patterns are known to correlate with viewing distance and strongly affect perception of stereoscopic shape and depth. There has been little analysis of the implications of recent findings on vertical disparity processing for the design of stereoscopic camera and display systems. I ask how such distortions caused by camera convergence affect the ability to fuse and perceive stereoscopic images.
Robert Allison, "Analysis of the Influence of Vertical Disparities Arising in Toed-in Stereoscopic Cameras" in Journal of Imaging Science and Technology, 2007, pp 317 - 327, https://doi.org/10.2352/J.ImagingSci.Technol.(2007)51:4(317)