Zoom control of wide area tracking system

Scale variant is a big problem for wide area security and the target can only be tracked within limited area. To solve this problem, this paper is going to introduce a scale invariant algorithm of zoom control using depth which is calculated by stereo camera. We proposed a wide area tracking system consists of three tracking functions, including the first saccade, second saccade and smooth pursuit. An eagle´s eye mechanism is proposed to get a wide field of view (FOV) in high resolution during tracking by three zoom cameras. We use two cameras set in different focal lengths as the first saccade camera and the second saccade camera to detect moving objects in wide area. The third camera with the highest resolution is used for smooth pursuit. After the target is caught by the smooth pursuit camera, both the cameras for saccade will zoom in to calculate the depth of the target by stereo vision. When the target is moving, the pinhole camera model is used to control the focal length of the zoom cameras to get constant scale of the target in the FOV. We report the experiment of depth from stereo camera and the zoom tracking result of the remote object from 125 to 175 meters. Experimental result shows the depth of the target can be calculated in real time and the constant size of the target can be gotten while tracking.