Research And Realization Of GIS Engine

WebGIS is a computer information system, which can store, manipulate, analyze, display and apply geographic information in Internet/Intranet environment.This article introduces six seedtimes of GIS: GIS model, Integrated GIS, Modular GIS, ComGIS, WebGIS. This article also describes five methods of WebGIS's application: CGI, Sever API, Plug-in technology, ActiveX, Java Applet technology.This paper anatomizes data format of shapefile and spatial index technology. On the basis of research on quadtree spatial index, this article improves quadtree spatial index technology into binarytree spatial index technology. When features are distributed symmetrically, the performance of binarytree spatial index is close to the quadtree spatial index; The more features are distributed asymmetrically, the better binarytree spatial index performances than quadtree spatial index.This article designs and develops a GIS engine. The GIS engine implements parsing data, transforming coordinates, rendering features. Parsing data is to read and analyze feature data from shapefile. Transforming coordinates is to transform from world system (WCS) to image coordinates.Rendering feature is to render feature objects onto a bitmap. This GIS engine adopts GDI+ to render feature objects.At the end of this article, the applications of this GIS engine are shown.