The Electronic Map System Based On PDA

With the development of embedded technology and wide application of wireless communication technology, Mobile GIS taking mobile intelligent terminal as carrier has already become the focus of GIS research.The Embedded GIS System is the outcome of GIS combined with new developing embedded hardware, which is the extension, supplement and development of the original GIS field. Embedded GIS is a software solution collecting with navigation, localization, and map inquiry and space data management, applied extensively. Mobile GIS is the latest form of Embedded GIS. On the basis of Embedded GIS System, it integrates the advanced individualized computer technology PDA, mobile communication technology (GSM/ CDMA) and GPS technology to expand the application of GIS system and improve the convenience and real-time of GIs information gathering and data processing. The advantage of Mobile GIS lies in that it can offer a kind of convenient, swift and reliable information inquiry and decision means to customers whenever and wherever possible.The thesis's research purpose is to achieve the real-timed geography information in mobile environment by making use of the Embedded GIS, GPS and PDA. At first, the thesis analyzes the present research, technique background, characteristics and applications of the Embedded GIS. And then this thesis analyzes many spatial data structures and typical data formats of geographic information system, and makes a detailed comparison and a election of data format used in the system. The shortest paths algorithm of the core algorithm of the system is described in detail. This thesis makes an integrated application of the improvement in the data storage structure and the search strategy of the classical Dijkstra algorithm. The sparse matrix storage structure is replaced by the adjacency list storage structure, and the unidirectional searching method is replaced by the bi-directional search method. So the efficiency of algorithms in the storage and search has been improved. And the thesis makes a presentation of the specific electronic navigation system. The data collection, real-time GPS reception and data conversion are discussed in detail, and the thesis also gives a instruction of the modules of the system. The system has many functions, including enlarging the map, narrowing the map, moving the map, and so on. The system is also available to the location by GPS and the shortest paths. This system has the feasibility and maneuverability, and can facilitate the lives of people, so it has practicality significance.In the end, this thesis summarizes the content and makes the simple future prospects on this basis.