Motion Parallax and Structure from Motion
Published Online: 30 JAN 2010
Copyright © 2010 John Wiley & Sons, Inc. All rights reserved.
Corsini Encyclopedia of Psychology
How to Cite
Braunstein, M. L. 2010. Motion Parallax and Structure from Motion. Corsini Encyclopedia of Psychology. 1–2.
- Published Online: 30 JAN 2010
Motion parallax and structure from motion are two related sources of information for the perception of the shape of 3-D objects and surfaces as well as the layout of objects and surfaces in 3-D scenes. Motion parallax refers to the inverse relation between the speed at which the projection of an object moves across the retina and the distance of the object from the eye. When the head moves horizontally, for example, projections of stationary objects closer than fixation move across the visual field in the direction opposite the head while projections of more distant objects move in the same direction as the head. The same is true for parts of objects or surfaces; the relative speeds with which objects move in the retinal projection provides information about their relative distances in the environment, assuming that the 3-D distances between the objects remain constant. This assumption is known as the rigidity constraint. Stationary objects move rigidly when an observer moves, but the validity of a rigidity constraint is less clear for moving objects. If the moving objects are associated with a continuous surface that is moving relative to the observer, a rigidity constraint may be reasonable.