The Organization And Rendering Technology Research Of Vector Data In 3D GIS

Geographic information system (GIS) is a combination of spatial information science and the modern geography, which is a foundation platform to do some observation and make decisions for traffic, ocean, geology and other industries. The traditional two-dimensional GIS can only monotonously show space information on a two-dimensional plane by using vector data such as points, polylines and polygons and so on.3D GIS not only contains vector data such as points, polylines and polygons, but also contains the DEM and remote sensing image data, which makes the result more intuitive and realistic. It provides a better visual way for information interpretation and spatial analysis. Therefore, socialization of spatial information application service urgently needs the support of 3D GIS, and 3D GIS has become one of the important development directions of GIS. Vector data is the most important information expression of GIS system. But vector data is a 2D information that don't be rendered as DEM and remote sensing images which can be rendered to 3D terrain. So how to render vector data in 3D GIS correctly and efficiently and ensure it fit closely with the 3d terrain has become a significant challenge. Therefore, this dissertation works around the above problem by means of analysis and research.In this dissertation, the main work can be divided into the following three points:1) Based on the geographic space division, the way of 3D GIS map projection and the organization of rasterizer data are discussed. A strategy that the vector data be layered and partitioned is put forward in order to adapt to the 3D GIS geospatial division and improve the rendering efficiency.2) A method based on texture is presented to realize a seamless overlaying of 2D vector data and 3D terrain. It organizes and renders vector data based on the vector texture pyramid to and uses anisotropic filtering method to improve the quality of paint and visual effect.3) A prototype system-3D GIS Data Rendering System is constructed, based a quad-tree structure to organize data. Through using many methods include quad-tree update dynamically, cone cutting and texture generated dynamically, it realizes the terrain elevation data, remote sensing image data and vector data seamless overlay mapping. Finally, the vector data has obtained a better rendering effect in 3D scene.