Detection and characterization of multiple motion points

The computation of optical flow is a well studied topic in biological and computational vision. However, the existence of multiple motions in dynamic imagery due to occlusion or even transparency still raises challenging questions. In this paper, we propose an approach for the detection and characterization of occlusion and transparency. We propose a theoretical framework for both types of multiple motions which explicitly shows the difference between occlusion and transparency in the frequency domain. Then, we employ an EM-algorithm for the computation of one or two image velocities and a simple test for the detection of occlusion. Our approach differs from other EM-approaches which blindly assume the superposition of two models in the spatial domain without providing with a separate formal model for occlusion. We test and compare the characterization performance on synthetic and real data