Based On Personal Travel Assistant For Mobile Gis Data Consistency

With the strong capabilities of data processing, geographic modeling and spatial analysis, and after more than 40 years of development, geographic information systems has penetrated into the social production and many aspects of human life. As a result of the development of computer network technology, global positioning system and social information, mobile GIS technology emerged. Mobile GIS technology can provide the mobility equipment. And with the help of GPS technology, it can provide a lot of space-effective services, which are related to the location. Mobile GIS improves the society's information degree and brings great convenience to the social production and human life. In the applications of mobile GIS, as a result of mobility of terminals and relative lack of wireless network resources, the data consistency of electronic map and server-side digital map come to a bottle-neck. This dissertation does some research on the update of digital map. And a new way is proposed, which is simpler and more suitable for the wireless application situation. Besides, the path planning algorithm for mobile terminals has been improved and implemented. The main work of this paper is as follows:1 Briefly introduce the mobile GIS and related technologies. Give the overall design and divide the modules, and describe the function of each module.2 Introduce the current updating methods of digital map (Update offline or online), and come up with a new update way based on broadcasting technology, which combines two digital map update methods. Judging from the updating frequency of digital map, update the frequently changed data with the method of online broadcasting, such as the traffic status information. Update the slowly changed data with the offline way, which pack the digital map data and upload it to the mobile devices. This update method not only meet the demand of latest data, but also save cost of wireless transmission;3 On the basis of real time update of traffic information, we optimize the path planning algorithm of the mobile terminal. Using Dijkstra algorithm, it optimize the search direction, reducing the unnecessary search. On the other hand, we use traffic information update triggered path re-planning approach to dynamically modify the path weights, and give the best path, which is suitable for the current traffic information.