When security applications meet high-definition satellite images (GIS)

  There are two types of integration of video surveillance and GIS in terms of functions. One is the more common one that marks the location information of cameras on the map to facilitate quick camera selection. This type of application often has a more prominent advantage in large-scale CCTV systems for urban monitoring...

    If the integration of positioning security applications and GIS is still obvious, then the integration of video surveillance and GIS is not so direct. There are two types of integration of video surveillance and GIS in terms of functions. One is the more common one that marks the location information of the camera on the map to facilitate the quick selection of the camera. This type of application often has a more prominent advantage in large-scale CCTV systems for urban monitoring. Shanghai's urban monitoring network has begun to use this technology to improve management efficiency in the late 1990s. However, this type of GIS or GIS-like applications cannot truly reflect the digital characteristics of GIS.

    The second type of application truly reflects the effectiveness of GIS digital quantitative monitoring, which is to integrate the PTZ action of the pan/tilt system with the GIS map. As we all know, common PTZ actions of cameras can only command the camera to rotate up, down, left, or right, or to zoom in or out. However, if you carefully study the extended protocol of PELCO-D, it is not difficult to find that the protocol also has instructions for rotating to the left by a certain degree and looking down by a certain degree. With this instruction protocol, it is not difficult for you to imagine how to react with GIS. By integrating PTZ cameras that support PELCO-D (or similar protocols) with GIS, the positioning and monitoring of the target can be completely separated from the "qualitative" management scope of preset positions or manual positioning. The operator can completely select a target on the map, and then calculate the angle and distance between the camera and the target through the GIS system. Then, by calling the absolute positioning instruction protocol, the target can be located at one time, and accurate video monitoring of the target can be achieved, simplifying the manual "qualitative" operation process into a "precise positioning, instant arrival" "quantitative" process. In fact, as early as the beginning of this century, some departments of the Shanghai Municipal Government had already had many successful cases of such applications.

    In the extended protocol of PELCO-D, the horizontal angle resolution can be accurate to 36,000 equal divisions, that is, the accuracy of a circle can reach 0.01 degrees. Some people may ask whether the precise position of 0.01 degrees is valuable for monitoring? Indeed, if the monitoring range is tens of meters or more than a hundred meters, it is indeed worth discussing whether it is necessary, but what if the monitoring is extended to 10km? Take a 1100mm lens with a 1/3" CCD camera as an example. Its horizontal image field is 0.25 degrees (horizontal image field width 43m). With an error of 0.01 degrees, the line error at 10km away is 1.8m. If the target is at the edge, it is completely possible to lose the target. Imagine that if it is based on the traditional "qualitative" monitoring method, manually rotating the PTZ camera, it is actually impossible to achieve an accuracy of 0.01 degrees. Only 1 degree of error is needed, and the deviation of 174m at the front end is enough to lose the target even if the target is a house. Under such harsh conditions, only accurate calculations based on GIS combined with PTZ cameras with absolute positioning functions for "quantitative" monitoring can truly capture the target. In fact, this function has extremely high application value in ultra-long-distance monitoring. Currently, in addition to the Pelco series of PTZs and HoneywellACUIX series cameras that support the extended PELCO-D absolute positioning protocol, some Japanese PTZ camera manufacturers, such as Japan Kenko, provide positioning accuracy of 0.001 degrees or even higher. These excellent features can only be truly effective in "quantitative" monitoring applications based on GIS, and it is this "quantitative" security application that enables the security industry to see farther and better.