Three-dimensional motion analysis by direct matching

We describe a direct-matching approach to determining motion of a rigid body from two time-sequential perspective views. The method does not require finding feature correspondences. It is valid under the following assumptions: (1) Brightness constancy—the brightness of an image point corresponding to a fixed object point does not change after motion. (2) The mathematical form of the object surface is known to within a finite number of parameters. We also show how the computation can be simplified in the case of small motion.