METHOD AND APPARATUS FOR DETECTING MOTION ACROSS A SURVEILLANCE AREA

摘要

A camera captures, in successive frames, images of an object moving across a surveillance area. Successive frames are correlated to identify moving regions within each frame and to evaluate motion vectors for each region. Each moving region is thus tracked across the surveillance area. If no moving region is found in a frame to correspond to a moving region in a previous frame, a check is made for a corresponding region in a background mask; the background mask is updated frame-by-frame. If no corresponding region is found in the background mask, the moving region is considered lost and a preliminary alarm state is set. A full alarm state is then set if either a moving region is tracked traversing the surveillance area in an illegal direction or a moving region is tracked entering the surveillance area, is lost, and then another moving region (which may, or is expected to, correspond to the same object) is tracked leaving or about to leave the surveillance area in an illegal direction while a preliminary alarm state is set.