In the design of visual simulation equipment for training systems, one key decision is the nature of the image storage medium to be used. One consideration in this complex issue is the adequacy of the depth cues which can be derived from imagery based on two- rather than three-dimensional sources. Although motion parallax is a relatively minor cue, it is the essential difference between imagery derived from two- and three-dimensional sources. This study was designed to investigate the role of motion parallax in the perception of apparent depth on a dynamic television display. Subjects were tested on their ability to perceive dimensionality as a function of altitude. The results showed that motion parallax provides a useful cue to depth only at very close ranges. It was concluded that for training problems which require simulation of television navigation and/or targeting imagery there is little or no advantage in the more expensive three-dimensional image storage devices for altitudes above 750 feet. (Author/JK)