Clipping And Merging Of Vector Data Based On Tile

The innovation of Web2.0 brings more room to the development of WebGIS, so that the combination of Web and GIS is more and more prevalent. But for theWeb map service, most current applications are provided with raster data, partly because the grid technology is relatively simple and more mature.on the other hand, it is limited by the inherent bottleneck of vector data. But it is the rapid development of the Internet that allows users to put forward higher requirements for interactions and response times.Therefore, in a Geographic Information System currently, if there exists too much interaction between a server side and a client one, it's not a good choice to transmit raster data repeatedly over the Web.To meet the situation above, after the research on the transmission technology of raster data and vector data, the expression technology of GML object, the clipping algorithms of vector graphics and so on, this paper promotes a mechanism for the combination of vector data, by clipping the data into tiles in advance, coupled with the asynchronous request function by the AJAX, so that, the waiting time in the client side is reduced and the user experience increased. The experiment was completed in a particular open source GIS environment finally. The experimental results showed that the more detailed for the level of the map service, the more satisfied for the performance of the experiment. During the operation for each panning, the amount of data acquired from the server was approximately 1/3 of the one in visible region, and the average interval between the successive two operations was about 3.2 second. The time will become a long interval with the refined of the level.