Design And Implementation Of WebGIS Based On Computer Graphic Metafile

WebGIS, which is the combination of internet and GIS, provides an effective tool for public to obtain GIS data and geographical information service. However, there are some problem in the development of WebGIS, such as poor interaction in client, limited ability of visiting isomerous spatial data , large compression of Web data transmission and difficult operation each other of spatial data, etc. Aiming at the shortage of share and operation each other of spatial data and poor interaction in client etc between WebGIS, discusses how to apply the technology of WebService into WebGIS and how to use the technology of Computer Graphic Metafile (CGM) to dynamic release the web map in this paper. Then leads the technology of data compression and designs an WebGIS based on Open GIS Consortium (OGC) geographic information Web service standard.The paper firstly introduces WebGIS theory and correlative technology, and analyzes advantages and disadvantages of current WebGIS realization technology, as well as some problems in development of WebGIS. Aiming at these problems ,on one hand, adopts technology of WebService based on the way of XML data communication, applications of different terraces can depend on this technology to implement the connection and integration each other,thus overcomes the difficulty of operation each other with spatial data. On the other hand, aiming at visualization of geographical data, raises two formats of vector graphics based on web, which were Scalable Vector Graphics (SVG) and Computer Graphic Metafile (CGM), and introduces their formats and graphic elements separately, furthermore deeply analyzes the document converting and structure coding. Lastly, the technology of CGM and Web Service is discussed, and based on organizing data and designing structure in WebGIS, a WebGIS model is created. The model uses Web Service to realize Web map service, chooses CGM to display Web map, and it does attempt on share and operation each other of spatial data. Some functions, such as layer displaying, inquiring about properties and information statistics based on CGM data, may be operated in this system. An example is designed to validate the feasibility of the designed WebGIS model in technique.