形状是由图像的轮廓形成的，所以理论上形状识别是通常在边缘或轮廓检测后的步骤。(edge_based_matching The shape is formed by the outline of the image, so theoretically the shape recognition is usually the step after the edge or contour detection)

Optic flow is an important cue for object detection. Humans are able to perceive objects in a scene using only kinetic boundaries, and can perform the task even when other shape cues are not provided. These kinetic boundaries are characterized by t