Virtual object distortions in 3D displays with only horizontal parallax

An imaging system that can convey a full 3D light field provides viewers with parallax in both the horizontal and vertical directions. However, displays that provide horizontal parallax only (HPO) are commonly preferred because they can greatly reduce cost and complexity, while still providing a good amount of 3D realism. Here we consider one side effect of HPO: the aspect ratio of displayed virtual objects will be observed to change as a viewer moves toward and away from the display. This results in object shape deformations that can only be corrected for viewing positions on a single line. We present an analysis of what happens outside these ideal positions, and how it is related to the range of object depths in the displayed scene. Several numerical examples and simulations of display views are presented to illustrate the effects, and show how they limit the acceptable range of scene depths and viewing positions of HPO 3D displays.