Ming Ye Robert M. Haralick Linda G. Shapiro Estimating Piecewise-Smooth Optical Flow with Global Matching and Graduated Optimization. 1625-1630 2003 25 IEEE Trans. Pattern Anal. Mach. Intell. 12 http://doi.ieeecomputersociety.org/10.1109/TPAMI.2003.1251156 db/journals/pami/pami25.html#YeHS03