ESTIMATING 3-D MOTION FROM RANGE DATA.

Methods are developed for estimating 3-D general motion (rotation and translation) parameters from 3-D range data at two time instances. The problem can be expressed in terms of linear equations consisting of correspondences of either points of unit direction vectors joining these points. Alternatively, no equations need be solved nor nonlinear expressions evaluated, as, for example, in the case of the screw motion method described here. It is shown that the best method (in terms of numerical accuracy) involves first obtaining two unit direction vectors from three correspondences, constructing a third orthogonal direction vector, and solving a three by three linear system to obtain the rotation. The translation then follows trivially once the rotation is determined. Simulation results are included.