Construction And Application Of WebGIS Based On GML & SVG

WebGIS is the product of the combination between Internet and GIS technology. The Internet user can access GIS data and obtain geographical information service from World Wide Web's at any node. Because of its simple operability, cross-platform support, expansibility and the sharing of information distribution, WebGIS has already drawn a widespread attention and been applied in many fields. But the present application of this technology shows that it is still immature, and is still facing a series of technical bottlenecks and challenges, such as the difficulties in geo-spatial information sharing and inter-operability, the lack of methods for denoting spatial information, the lack of capabilities to realize the cross platform data access, the transmission speed bottleneck, the visualization and the distributional work and so on. In the paper, the technologies such as Web Services, Ajax, the geography markup language (GML) and the scalable vector graphics (SVG) were used, in combination with the Open Geospatial Consortium (OGC) geographic information web service standard for reference, to solve some of the above problems in the WebGIS like the ones in the geospatial information sharing and inter-operation, the bad interaction in client and the limited capability in asynchronous structure spatial data accessing and so on.In the paper, the concepts and the characteristics of WebGIS were first introduced, then, after the analysis of the current WebGIS main realization technology, the problems in the current WebGIS development were brought forward. Then the WebGIS technologies based on Web Services/Ajax, GML/SVG were explored and discussed, and finally a prototype WebGIS system-GSWebGIS, based on the WebGIS system structure design and the data organization, were developed. In this prototype system, the web service technology was used to realize the web map publishing service and the data conversion service. Moreover, by using the Ajax technology , GML as the unified geographic information description language, SVG as a geography information visualization tool, not only the client interactivity can enhanced, but also a lot of WebGIS functions such as map basic operation functions map query/SQL query function thematic mapping function and data conversion function can be realized. The prototype system also solved the problems to some degree such as the geographic information sharing and inter-operating problems.