The realization of advanced search functions on SVG-based vector WebGIS map

SVG is a sort of markup languages based on XML,it is used to describe two dimension vector graphics and vector/raster mixed graphics.Though SVG is not a standard that be made in order to the release of spatial data of geography,but a lot of characteristics of it can be widely applied to WebGIS,thus the vector WebGIS can be realized.Because SVG describe vector picture by the format of simple text,so the data amount of SVG is usually very little,and SVG can be compressed through GZIP,so the WebGIS that be constructed based on SVG can lighten transmission load of the network and accelerate the display pace of the map.SVG can support JavaScript by itself,and SVG can be mapped into the tree structure in the memory through DOM,so the client can operate DOM by JavaScript to realize the scale,the roam,the inquire,the control for the map layers,etc.