Svg-based Spatial Data Expression And Organization Of Key Technologies

With the development of mobile communication technologies, the demands of the people for location-based services are more and more extensive. So many scholars become focus to the research of LBS(Location Based Services). But LBS based on GIS with its own some characteristics:such as limited bandwidth and computing power, limited display size, different data formats, various data standard, diversiform mobile terminal, no complete enterprise-class solution, and so on. These questions caused many contradictions to limit the industry's development. Including GIS services in the development of wireless communication are conditioned, hindered different mobile terminal data reorganization and sharing, the poor coupling between these solutions such and so on.In view of the existing sorts of problems, Scalable Vector graphics SVG (Vector Graphic) was used to become the solution of data expression and organization in LBS. It met the demand of most mobile users and providers. Compared with traditional GIS data format, there are some advantages in SVG, such as small size of data, data transmission efficiency, less distortion, strong interactivity, good flexibility, strong support with most commercial standards. So it is suitable for the mobile customers in location based services. But the existing methods of multi-source heterogeneous geographic data into SVG are lack of uniform standard, conversion effect is not good. There has not be system solutions to express and organize data based_SVG., especially data compression method based on SVG was single, need to be further studied.According to the problems of vector spatial data conversion, expression and organization in mobile terminal, the paper compared and expanded the existing schemes. Put forward a set of new system solutions about data expression and organization based on SVG;Researched the conversion methods form grid and vector data to SVG, and validated the conversion effect with Harris corner detection; Studied the integration expression model for attribute data based on the combination of inline and outside theories, and validated the model with experiment;Improved traditional organization way using layers with LOD theory to reduce the data flow and control visualization;Especially researched and solved the key technology of data compression by using the combination downsizing expression and GZIP compression;Developed the prototype system based on J2ME platform with the theory of SVG data expression and organization;And verified the feasibility of technology solutions.