Occlusion event detection using geometric features in spatio-temporal volumes

In video sequences, edges in 2D images (frames) produce 3D surface in the spatio-temporal volume. In this paper, we propose to consider temporal collisions between edges, and thus objects, as 3D ridges in the spatio-temporal volume. Edge collisions (i.e. ridge points) can be located using the maximum principal curvature and the principal curvature direction. Using the detected ridges, we then propose a technique to identify overlapping objects events in an image sequence, by neither computing depth nor optical flow. We present successful experiments on real image sequences.