Collision and event detection using geometric features in spatio-temporal volumes

In video sequences, edges in 2D images (frames) produces 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. Collisions (i.e. ridge points) can be located using the maximum principal curvature and the principal curvature direction. Using the detected collisions, we then propose a technique to detect overlapping objects events in an image sequence, by neither computing depth or optical flow. We present successful experiments on real image sequences.