A curvature-based approach to contour motion estimation

We present a novel method of velocity field estimation for points on moving contours in an image sequence. The method determines the corresponding point in the next image frame by considering curvature changes at each point on a contour. In previous methods, there are errors in estimation for the points which have low curvature variations since those methods compute the solutions by approximating the normal component of optical flow. The proposed method computes optical flow vectors of contour points by minimizing the curvature changes. As a first step, snakes are used to locate smooth curves in 2D imagery. Then, the extracted curves are tracked continuously. We excluded the rearranging process in snakes and allowed the snaxel distance to vary. Each point on a contour has a unique corresponding point in the nest frame. Experimental results showed that the proposed method computes accurate optical flow vectors for various moving contours