Lucas-Kanade 跟踪算法，此算法实现了经典Lk跟踪，详细算法参见文章 An Iterative Image Registration Technique with an Application to Stereo Vision (IJCAI), B.D. Lucas and T. Kanade, 7th International Joint Conference on Artificial Intelligence (IJCAI), April, 1981, pp. 674-67