Svg-based Webgis Applications

WebGIS, a product combined with technologies of GIS and Internet, is a computer system used to store, analyze, apply and deal with geographic information. Though experienced a substantial development in the past two decades, it still has its weaknesses, such as in the sharing and interoperability of spatial date, the out-of-fashion map form, the heavy web transmission and the slow response of server.SVG, a XML based description language of vector graphic put forward by W3C, can solve the problems above. The vector map based on SVG, has many advantages over raster map (JPEG, et.), such as small file, high quality graphic, strong interactivity, searchable graphic content and so on. The advantages above can meat the requirement of graphic displaying of spatial data for GIS well, which makes it possible to be an efficient format for the visualization of spatial data.This paper analyzed the features and grammar of SVG, studied the implementation techniques of SVG based WebGIS, and then designed a bus query system based on SVG The system took the map of Nanjing for example, adopted Oracle's spatial database component, "Oracle Spatial", to store spatial data, realizing integrated management of spatial data and feature data, built up a GIS application server and SVG based graphic interface at user's end for the interactivity between users and databases with SVG, JSP, JavaScript, and JDBC, realized functions such as map displaying, map control, bus query etc, and obtained ideal result.