Motion Segmenation and Depth Ordering Based on Morphological Segmentation

Abstract

In this paper the motion segmentation and depth ordering problem for monocular image sequences with and without camera motion is addressed. We show how a new multiscale morphological segmentation technique, based on the watershed, can produce a superset of the motion boundaries. Regions with similar motion then have to be merged. The difficulties of motion estimation at object boundaries with occlusion are analyzed and a solution combining segmentation and robust estimation is presented. Region merging is then performed using the obtained motion parameters. We then present a new technique for the depth ordering of the resulting image partition. We show how the modelling error on either side of the motion boundary can be used to indicate the occlusion relationship of the objects. The algorithm is then applied to several synthetic and natural image sequences. The results demonstrate that the technique is robust and that the depth ordering requires only minimal motion to perform correctly. This is due to the fact that, unlike existing techniques for depth ordering, the motion between two frames only has to be analyzed. We then point out possible improvements and indicate how temporal integration of the information can further increase stability.