14 May 2000
14
ACES ATTACK!
•Often considered the most important cue to depth perception.  Motion parallax refers to the apparent, relative motion of stationary objects as viewed by an observer who is moving across the landscape.  Near objects appear to move past or opposite the path of motion; far objects seem to move in the direction of motion or remain fixed.  The rate of apparent movement depends on the distance the observer is from the objects.  Objects near the aircraft appear to move rapidly, while distant objects appear to be almost stationary.  Thus objects that appear to be moving rapidly are judged to be at a greater distance.  For example, grass along a road goes past very rapidly because it is close…trees a little farther out seem to go by a little slower, and mountains in the far background of your view seem to either sit still or move with you.  From this, the mountains are judged to be at a greater distance from the observer.
Motion Parallax