Development Of GPS Vehicle Monitor Function In 3D GIS For Shanghai Public Security Bureau

With the development of GPS, the technology of GPS is widely used in public traffic. In recent years, police cars, fire engines, ambulances, security and many civilian vehicles are equipped with GPS devices, which can be used for navigation. Facing increasing GPS vehicles and more complicate traffic conditions, more and more researchers focus on how to implement effective monitoring and management of GPS vehicles. Based on GPS navigation technology, combined with wireless communication technology and GIS technology, the GPS vehicle monitoring system has become a key part of GPS vehicle navigation and has relatively broader development prospects at home and abroad.In the GPS vehicle monitoring system, GPS provides an effective way to obtain spatial data, and GIS has powerful spatial data management capabilities. The combination of the GPS and GIS could implement vehicle dynamic positioning, visual management and real-time monitoring. Wireless communication network is a bridge to combine GPS and GIS.The current GPS vehicle monitoring system is using two-dimensional electronic map to display the GPS location information, while the urban transport network is a three-dimensional space, which has a complex hierarchy changes. The two-dimensional electronic map uses the vertical projection which can not show the third dimension z values; therefore, the object with complex three-dimensional hierarchy such as overpass and viaduct could not be exhibited. This may easily mislead the driver and make the driver lose confidence in vehicle monitoring system. At the same time, in the two-dimensional electronic map, vehicles are displayed in pictures, and running process of vehicles is discontinuous, which may cause inaccuracies and errors.The rapid development of the three-dimension geographic information system technology (3D GIS) has led to the development of GPS/3D GIS applications. Therefore,3D GIS's outstanding visualization effects and unique three-dimensional functions have good application effect and broad prospects in GPS vehicle navigation. Especially for GPS vehicle monitoring center of Intelligent Transportation System(ITS),3D GIS provides direct virtual reality environment and rich map control capabilities; it is very important for dispatching management and is the basis for subsidiary decision-making for dispatcher and administrators.By the use of existing 2D GIS platform for Shanghai Public Security Bureau and road data, GPS navigation data, etc, the paper has developed GPS Vehicle Monitor Function in 3D GIS for Shanghai Public Security Bureau. By this function, vehicle's running process is displayed in 3D visual form, which has avoided the lack of two-dimensional map and the complex traffic environment display error.The paper describes the design of 3D GIS for Shanghai Public Security Bureau, introduces the four stages to achieve the GPS vehicle monitoring capabilities:data preparation, road matching, match result processing and 3D visualization monitoring.