Research On Creation And Visualization Of Large-scale Digital Elevation Model

As one of frame data of National Spatial Data Infrastructure , Digital Elevation Model excels contour line. it can express continuous gurgitation of ground, and it can also carry out relevant mathematical analyses and imitation, so it is applied broadly in various fields at present. Large-scale Digital Elevation Model is foundation of spatial information in CyberCity and provides a great deal of information for 2D map and 3D model of CyberCity, and it provides a kind of efficient method to manage,store and maintain a great many data of cities' elevation. it provides a strong sustaining platform for digitization of cities'establishment,3D cities' simulation model ,city planning, design of sight in town and foundation of virtual reality.This paper uses Digital Line Graphs for original data . After author bases on Large-scale relief map' feature and analyses the feature , data structure and creation algorithms of two main representation shape—Triangulated Irregular Network and regular grid , author provides a kind of method that large-scale DEM is created from TIN which is created from large-scale DLG. After the paper sufficiently considered creation algorithmic of triangulated irregular network in time and space and analyzed three creation algorithms of TIN-divide-conquer, triangulation growth, incremental insertion, the paper adopts to a new algorithm that takes advantages of divide-conquer and triangulation growth. It can create TIN quickly. The paper also uses break lines, terrain feature lines ,building borderlines to be restriction condition and creates triangulated irregular network based on restriction. In order to ensure to get stably reliant explain when DEM is generated from TIN interpolation, author adopts to bilinear interpolation and carries out quality examination of DEM.Because Digital Elevation Model is abstract data, it is difficult to understand and take in. Based on expatiation of the theory on visualization, technical measure, the theory of real terrain and the modeling techniques on real-time dynamic display of 3D terrain, author has made uses of OpenGL to realize terrain visualization based on DEM.