In this paper ASSET-2, a complete real-time vision system for segmentation and tracking of independently moving objects, has been described. ASSET-2 requires no camera calibration or motion registration, and performs all calculations in the image plane. Information gained from the motion of two dimensional features is integrated with one dimensional boundaries. ASSET-2 achieves automatic instantiation of tracking for each new object detected, and any number of objects can be tracked. Occlusion of one object by another or by a ``static'' part of the scene is correctly handled. The temporal integration of segmentation information in such a robust and flexible way is a step forward in the area of image sequence understanding. The results presented show ASSET-2 performing reliable and accurate object tracking for several image sequences.
In the near future ASSET-2 will be extended to incorporate knowledge of the world so that simple estimates of the three dimensional positions and motions of objects in its field of view can be made (this has already been done for the simple case of motorway traffic monitoring). The ASSET-2 system will be integrated with a structure-from-motion system which recovers world structure in a static environment. ASSET-2 will be used to segment out and track moving vehicles, and the static part of the scene will then be tracked by the structure-from-motion system.