3D WebGIS Constructing And Application Based On HTML5and WebGL

3D webgis is an important branch of GIS industry, it satisfies people’s need for3d geographic information, and the current3D webgis has been widely used in tourism, planning, e-commerce and other fields. Traditional technology for3D webgis client are Flash, Silverlight, Java, Applet, VRML and X3D, however, there are always some shortages in them, like openness, cross-platform, plug-in dependency, hardware acceleration, how to build an open, platform-crossed, plug-in free3D webgis has always been a tough task.Through the research and analysis of the traditional application mode and client technology for3D webgis, we summarize the defects of traditional implementation technology. To cover the shortcomings of the existing traditional3D webgis, this paper uses the new technology of HTML5and WebGL and introduces a new method for3D webgis build-up. On the above basis, the author develops the prototype system for this method and realizes it in campus. This paper first establishes the system application mode for3D webgis system,then into the system demand analysis, structure design, function design, database design; Then this paper studies the establishment of terrain and surficial buildings and the method of using WebGL for terrain rendering, and these methods are realized; Finally research and implements the two-dimensional navigation, light regulation, the optimal path query,roaming, selection of object, translation, scaling, rotation, etc.This system organizes data through JSON format, delivers data by AJAX, and displays3D data with HTML5and WebGL technology and acquires excellent rendering and high rendering speed. Results illustrate that the system provides a good experience of interactive3d visualization, and has the advantages of plug-in exemption, cross-platform, openness as well as hardware-based acceleration. It defeats the weakness of traditional3d webgis like plug-in-dependence and privacy, shortens the distance between desktop application and Web application, thus, it is a new and very effective and promising method for3d webgis realization.