Determining object motion in a sequence of stereo images

The motion of a three-dimensional object is determined from a sequence of stereo images by extracting three-dimensional features, establishing correspondences between these features, and finally, computing the rigid motion parameters. Three-dimensional features are extracted from the depth map of a scene. A two-pass relaxation method is developed for matching features extracted from successive depth maps. In each iteration, geometrical relationships between a feature and its neighbors in one map are compared to those between a candidate in the other map and its neighbors to update the matching probability of the candidate. The comparison of the geometrical relationship is based on the principle of conservation of distance and angle between features during rigid motion. The use of three-dimensional features allows one to find the rotation and translation components of motion separately via solving linear equations. Experimental results using several sets of real data are presented to illustrate results and difficulties.