ABSTRACT
In this chapter, the authors focus their discussion of optical flow on the gradient-based and correlation-based techniques because of their frequent applications in practice and fundamental importance in theory. They discuss multiple attributes techniques in optical-flow determination. Optical flow is caused by movement of intensity patterns in an image plane. Aperture problem is an important issue, originating in optics. Since it is inherent in the local estimation of optical flow. It can be shown that the two-dimensional (2-D) motion field and the optical-flow field are equal under certain conditions. The aperture problem becomes severe in image regions where strong intensity gradients exist, such as at the edges. The optical-flow field is a dense 2-D distribution of apparent velocities of movement of intensity patterns in image planes, while the 2-D motion field can be understood as the perspective projection of three-dimensional motion in the scene onto image planes.
