Ming Ye Robert M. Haralick Local Gradient, Global Matching, Piecewise-Smooth Optical Flow. 712-717 2001 conf/cvpr/2001 CVPR (2) http://doi.ieeecomputersociety.org/10.1109/CVPR.2001.991034 db/conf/cvpr/cvpr2001-2.html#YeH01