【作者】 韩艳；

【导师】 张献州；

【作者基本信息】 西南交通大学 ， 地图制图学与地理信息工程， 2008， 硕士

【摘要】 20世纪50年代后期,DEM开始被采用并受到了极大的关注,它在测绘、土木工程、地质、矿山工程、景观建筑、道路设计、防洪、农业、规划、军事工程、飞行器与战场仿真等领域得到了广泛的应用。DEM的理论和技术范畴涉及到数据采集的技术和方法、数据结构的设计和处理、模型构建与内插算法的研究及算法的实现、DEM的三维可视化技术、DEM的精度评价及其质量控制以及计算机技术发展水平等。长期以来,人们一直对DEM表示地形的精度、数据采集、粗差探测、质量控制、数据压缩、可视化、DEM的应用以及不规则三角网TIN的建立与内插等技术方面进行着不断的研究。随着计算技术的迅速发展和DEM的广泛应用,寻找快速建模、内插精度高、可视化程度高的建模方法是非常必要的。DEM可以使用一个或多个数学函数对地形进行表示,这样的数学函数通常被称为内插函数。当DEM表面建模后,模型上任意一点的高程信息就可以从DEM表面上获得,这与曲面几何造型非常相似。因此,DEM表面建模可视为地形表面的曲面造型。正是由于以上原因,我们可以将自由曲面的构造方法应用于DEM表面建模之中,同时还可以将自由曲线构造法用于构建地形模型的断面线。本文主要对地形表面模型的建模及其断面图生成的方法进行了研究,主要研究内容如下:1、结合国内外对地形表面建模的研究现状,阐述了地形表面建模研究的意义。2、介绍了现有的基于规则格网(GRID)和基于不规则三角网(TriangulatedIrregular Network—TIN)两种数据格式的地形建模方法,总结了三维地形表面建模的表现方法及特点。3、由于外业采集的数据常为离散点数据,需先构建不规则三角网再经过内插得到规则格网数据。因此,本文深入研究了不规则三角网的构网方法,对TIN的构网方法进行了改进,并用VB编程实现,以便提高其效率。4、对几种常用的DEM内插方法进行了研究,并从内插精度、适用范围、计算量等方面进行了比较分析。5、对自由曲线曲面的构造方法和三维数据场可视化理论进行了研究,总结了B样条基函数的优点和性质。6、将自由曲线构造法中的准均匀B样条方法用于地形模型断面图的生成以及对隧道断面测量的粗糙度分析与评价。7、基于准均匀B样条构造曲线曲面的方法,在MATLAB的编程环境下对一组规则格网数据进行了三维地形表面建模,并实现其可视化。更多还原

【Abstract】 From 20 century 50 age later, Digital Elevation Model (DEM) have been adopting and getting infinite attention. It is broadly used in many fields, such as Surveying, Civil Engineering, Geology, Mine engineering, Sight Architecture, Road Design, Prevent or Control Flood, Agriculture, Programming, Military Affairs Engineering, Aircraft and Battlefield Emulate and so on.The theory and technology of the DEM include the technique and means of gathering data, designing data structure, making model, research and putting into practice arithmetic of interpolation, 3D visualization, estimating accuracy, quality control about the DEM, and interrelated computer technology, etc. So far, the above-mentioned theory and technology about the DEM are researched continually.With the rapid development of computer and extensive application of DEM, it is very necessary to find out a modeling method with faster modeling, higher precision and better visualization quality.DEM uses one or more mathematical functions to portray the terrain. This function is usually called interpolation function. If DEM has been built, elevation information of everypoint on the model can be easily acquired. It is similar to geometric modeling very much, so that the DEM surface models can be regarded as surface modeling of terrain. Therefore, we can use the construction methods of free-surface to DEM modeling. At the same time, we also use the construction methods of free-curve in cross-section.The contents researched in this thesis are as follows:1. Combine with the study of terrain surface modeling status in the world, explain the significance of the terrain surface modeling’s study.2. Introduce the means of terrain modeling base on two data format—GRID and TIN, summarize the methods and characteristics of terrain surface modeling with three dimensions.3. Because of the data which collected from field works is discrete, it need convert into GRID. So this paper studys the network construction methods of Triangulated Irregular Network earnestly, improves the arithmetic of TIN and realizes the new method based on the VB platform.4. Compare and analyze the interpolation arithmetic which has been put into practice from interpolation accuracy, scope of application, computational complexity and so on.5. Learn construction methods of free-curve (surface) and theoretics of three-dimensional datafield visualization, summarize the merits and properties of B-spline basic function.6. Put the quasi-uniform B-spline curve’s construction method into sectional drawing and analysis and evaluation of tunnel cross-section’s roughness. Quasi-uniform B-spline is one kind of the free-curve construction methods.7. Using the MATLAB software to carry out the quasi-uniform B-spline, realize the three-dimensional terrain surface modeling and visualization.更多还原