Radars are fantastic geospatial sensors and nowadays, they are actually quite affordable for general perimeter surveillance. However, radars lack the ability to give a visual identification to allow the operator to determine if this is a good guy or a bad guy. However, combining radar with a geo-referenced PTZ camera can accomplish this verification task. This can be accomplished using two different methods: manually, or semi-automatic.
The first method is used for manual operator selection and normal alarming. It involves the radar continuously providing the target’s updated location to a video management system, such as PureActiv. The VMS then repositions the camera based on the object’s speed, heading and new position. Although effective, this form of camera repositioning is based on the update rate of the radar and results in a stop-stare, stop-stare type motion. This type of video tracking is show in the above video. You can see each time the camera re-centers after it is given new data from the radar.
The second form of verification utilizes video analytics capability to perform an automatic target follow. Using this method the radar provides the initial target position, but once the target is acquired, video-based tracking is used (PTZ Follow or Camera Auto Follow). This capability continuously steers the Pan-Tilt-Zoom camera to maintain a continuous view of the target. The advanced tracking is not impacted by posture changes, occlusion of the target by trees or poles, changes in target speed, direction or even sudden stops. Although it receives the initial cue by the radar, the subsequent tracking is performed using only video data. This allows the cameras to be repositioned multiple times per second, which provides a much smoother tracking motion for target identification. The algorithm allows for automated control of pan, tilt and zoom, keeping the target centered in the field of view throughout the entire coverage area of the PTZ camera. Should the video lose the target, it can query the radar for the target’s current position and reacquire.