Multi-resolution optical flow estimation using adaptive shifting

This paper addresses the problems of high spatial resolution in the estimated optical flow velocity vector map and robustness to large object displacement. We present a novel multi-resolution adaptive shifting method (MRAS), which uses variable image region shifts to refine velocity vectors calculated using the optical flow constraint equation at each level in a multi-resolution Gaussian pyramid. Furthermore an overlapping window technique is presented to overcome the spatial resolution limitations of the multi-point approach. The performance of MRAS is compared to a published multi-resolution clustering (MRC) technique, for two image sequences. Significant improvements in robustness with respect to large displacements is shown for MRAS compared to MRC, with little degradation in velocity vector accuracy as the magnitude of the displacement increases.