A New Retina-Like Visual Sensor Performing the Polar Transform

This paper describes the development of an anthropomorphic visual sensor with retina-like structure to perform the polar mapping. The sensor consists of a dove prism for image rotation and a linear CCD sensor with 512 pixellline resolution, and holds approximately 45 Kbytes of image data. The retina-like sensor has variable resolution with increasing density towards the center of the visual field, and performs the polar transforming directly. The motion equation that relates the egomotion and/or the motion of the object in the scene to the optical flow is considerably simplified if the velocity is represented in a polar coordinate system, as opposed to a cartesian representation. Development of this sensor holds promise in application to high speed tracking systems, such as the eyes of navigation robots, because it has a data reduction characteristics and mapping function onto the polar plane.