Three-dimensional Visualization Of Geographic Information Based On Geovrml

The thesis analyzes current visualization techniques taking terrain data, satellite images, thematic maps of Song-Liao river basin's typical area as foundational data, and exploits fast picking-up, real-time dynamic visualizing display, and spatial analysis methods on large DEM data based on GEOVRML, which is useful for reference to the study of 3D geo-information visualization.The thesis combines GEOVRML and spatial graphics database organically, and it also resolves conversion problems from DEM to GEOVRML files. The thesis achieves fast, exactly, real-timely display of numerous data by simplifying and expressing large terrain data in different resolution under the environment of GEOVRML.The thesis is divided into five chapters as follows: The first chapter summarizes the development trend of 3D visualization of geo-information and the present study about it at home and abroad, and then shows the main study content, aim, the source of study data, and data processing and analysis methods. The second chapter explains foundational theories of geo-information 3D visualization system and basic principles, methods, key techniques of 3D GIS development, including construction of 3D spatial model and terrain model, principles of data conversion, terrain simplification, and 3D visualization. The third chapter studies the characteristics, core concept, system structure of GROVRML and the construction of LOD. The forth chapter discusses modeling techniques in virtue of the ability of expressing geo-information based on GEOVRML, and brings to success of fast dynamic 3D terrain display and spatial analysis on it, taking Song-Liao river basin as study area. The fifth chapter summarizes the main contents of this article and prospects the application perspective of GEOVRML in 3D GIS.