Motion detection in security applications using tracking and hierarchy
Graeme A. Jones · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1994
In security monitoring, the false alarm rate may be reduced if intelligent reasoning is applied to moving regions identified in each camera. Stable objects of appropriate size, position, and velocity may be allowed to trigger alarm. In the following, moving regions are identified against a stationary background by thresholding accumulated image differences. Tracking allows the frame-to-frame feature correspondences to be established, and the feature motions and covariances to be updated. Regions extracted in this manner are often not stable for more than a few frames. In order to cope with this, a two level hierarchical scheme is introduced in which groups of features of consistent 2D motion are grouped into moving regions of interest (MROI) each attributed with their own 2D motions. A hierarchical matching scheme is then employed to guide the matching of MROIs and regions. Such an approach provides the spatial and temporal stability absent at the moving region level. In addition such high level features are the appropriate level at which to reason about image events in the context of security.