Study On A GML&SVG-Based Model And Its Application

As people's needs of geospatial information are rapidly increasing, traditional WebGISs meet their limitations.At first,the share of geospatial information is limited. Open internet environment and large scale data resources require data sharing.But products of different vendors usually have different storage formats for geospatial information.This means a GIS server needs a special transfomation before using GIS data in unsupported format.Maybe this transfomation is yet unsupported by the server.And different WebGIS vendors have different plug-ins for user explorer.This means a user need to download different plug-ins if he want to access different GIS server.Secondly, geospatial information usually has huge data size,and in traditional WebGISs the presentation of geospatial information,which transfered from server to client,is vector graphics or raster image which has an inefficient compress rate.So the network load is heavy,which can influence the effect of the application system and the effect of the network.The appearance of new XML_based technology,such as GML and SVG,bring chances to solve the limitations of traditional WebGISs.GML is the defacto exchange standard of geospatial information.Transparent sharing of geospatial information can be implemented through GML.Because of its advantages in quality, performance and size,SVG is adapt to be a tool of geospatial information visualization and to be transfered on network.A WebGIS model based on GML and SVG has been present,on which WebGISs can conquer the limitation of traditional WebGISs.This model has a Browser/Server multi_layer architecture,it requires GIS server to support GML,and it uses XSLT in transformation GML to SVG on server side.The server responses the GIS request of guest explorer with SVG.The guest explorer only needs support with a universal plug-in .Application systems based on this model can share geospatial information freely and transparently,and the network load is lower. An implementation of this model has been present,and the methods to implement an application system based on this model have been discussed by it's layers.The difference between these mothods and implementations of traditional WebGISs has been pointed out.As an emphasis,the implementations of the new layer,middle layer,have been analyzed with an application map example on how to use XSLT to transform GML to SVG.