Abstract
To obtain motion parameters from a moving object in a time‐varying image or to obtain information on a three‐dimensional structure and the collocation of an object, it is necessary to obtain the displacement from the object on the image prior to further processing. For this purpose, the gradient‐based method by which the motion of the object on the image can be detected directly form the spatio‐temporal changes of its brightness is widely used. However, in cases where the image contains noise or the conditions required for the gradient‐based method are not satisfied, a large error occurs in the estimation of the object.
This paper proposes a method in which the optical flow is represented using polar coordinates, and all the conditions required for its magnitude and argument are considered when they are derived. The magnitude of the optical flow of a pixel and the correlation between its argument and neighboring pixels are examined using true motion. The method detects only the optical flow caused by true motion of an object, eliminating optical flows caused by noise, so that the gradient‐based method may be applied.