Robust Computation of Optical Flow

This paper presents an algorithm to compute optical flow accurately at motion discontinuities and occlusion regions based on a robust estimator (the Least-Median-Squares estimator). The motion constraint equation and the 2-D affine motion model are used to compute the optical flow in a local neighbourhood. The use of the least-median-squares robust estimator enables points where optical flow cannot be computed to be rejected as outliers rather than assigning erroneous flow to such points. In addition, the use of an overlapping neighbourhood strategy eliminates the blockeffects that are commonly faced in local differential methods for computing optical flow. The algorithm is also able to deal with cases of the local neighbourhood straddling regions of three motions. Results for both synthetic and real image sequences are presented.