Further Discussion and Summary on 2-D Motion Estimation
This chapter presents a general characterization of two-dimensional (2-D) motion estimation. It explores different classifications of various methods for 2-D motion analysis. The chapter is concerned with a performance comparison among the major techniques. It introduces more advanced techniques and new trends in motion analysis and motion compensation. There are two types of motion: rigid motion and nonrigid motion. Rigid motion refers to motion of rigid objects. Because of the ill-posed nature of 2-D motion estimation, a unified point of view regarding various optical flow algorithms is also applicable for block matching and pel recursive techniques. That is, all three major techniques involve extracting conservation information and extracting neighborhood information. Neighborhood information manifests itself in that all pixels within a block share the same displacement. Neighborhood information manifests itself as recursively propagating displacement estimates to neighboring pixels as initial estimates.