上海三维城市工程地质建模研究

ABSTRACT
Along with speeding up of Shanghai urbanization advancement, the contradiction of urban development and the shortage of land resources is increasingly prominent. The underground space, as an important natural resource of sustainable development, has become an organic constituent of the Shanghai urban construction and utilization of the underground space has entered the moderate new developing stage. It is is extremely essential and feasible that an 3D digitized geological GIS platform is established to carry on monitoring, analysing, researhing the above underground spatial geological environment problems, to provides the technical support for plans for the urban underground space utilization and management, to safeguard the project in construction and operation. The key of 3D Digitized Geology is the 3D geo-modeling. The method of traditional 3D geo-modeling include the digitized modeling and geometric modeling. The digitized modeling can describe the attribute of inner physics and chemistry in the geological body better and can’t describe the spatial shape of the geological body well. And it is opposite to the geometric modeling. Therefore, the regular method is to synthesize the applied digitized modeling and geometric modeling in the research of 3D geo-modeling . That is to express the attribute of the geological body by digitized modeling and describe the spatial geometric shape of the geological body by geometric modeling. Then whether we can construct one model which can not only describe the spatial geometric shape of the geological body, but also express the inner physical and chemical attribute and avoid the problem of separation between the spatial geometric shape and inner attribute in the geological body of the traditional 3D geo-modeling is the present important research problem. The goal of the thesis is to solve this problem and the author does a lot of research work. The basic thinking is to introduce volume visualization to 3D geo-modeling and to construct the voxel model of the geological body by the technique of volume visualization. The voxel model can show both the spatial geometric shape and the inner physical and chemical attribute of the geological body. The geological volume data are divided into two basic types ,regular geological volume data and irregular geological volume data. For visualization of regular geological data set, the thesis analyses many classic visualization algorithms of regular 3D data set firstly. Then three kinds of algorithm are presented for regular geological volume data. They are the approach of construction from cross section, the approach of construction from voxel, and ray-casting volume rendering approach. For visualization of irregular geological data set, the paper focus on the principle and implementation of constrained tetrahedralization, which is the key for visualization of 3D irregular data set. The research includes the basic theory of triangulation, several classic delaunay triangulation algorithms. The thesis discusses the reconstruction of geological surface and geological body in succession. An approach for reconstruction of geological surface was presented, which is to divide scattered points into different regions and then the points of different region are triangulated by 2D delaunay triangulation. An approach of sewing two surfaces is also presented in order to form a closed boundary surface of geological body. The geological body are tetrahedralized by using the TINs of geological surfaces as constrained faces. The voxel model constructed by above approaches expresses not only the spatial geometric shape of the geological body but also inner attribute in the geological body. Also the voxel model provides a basic model for further 3D modeling, including cutting model, creating iso-surface. The author selects a 3D GIS platform from several 3D system and using the platfrom to conduct
上Fra Baidu bibliotek交通大学 硕士学位论文 上海三维城市工程地质建模研究 姓名：刘映 申请学位级别：硕士 专业：软件工程 指导教师：李治柱 20060201
上海三维城市工程地质建模研究 摘 要
随着上海城市化进程的加快，城市发展与土地资源短缺的矛盾日益突出。地下空间作为城市可 持续发展的重要自然资源，对它的开发利用已成为上海城市建设和改造的有机组成部分，进入了适 度发展的新阶段。建立一个三维数字化的地质 GIS 技术的信息平台对上述地下空间地质环境问题进 行监控、分析、研究，为城市地下空间开发利用规划与管理提供技术支持，以保障工程的施工建设 和安全运营是非常必要，而且也是可行的。 地质三维数字化的核心是三维地质模拟。传统的三维地质模拟方法通常包括数字化构模与几何 构模，其中数字化构模方法可以较好地描述地质体内部的物理、化学属性，但对于地质体空间形态 的描述能力较差；几何构模方法则相反。因此，目前三维地质模拟研究中，常规的处理方式是综合 应用数字化构模与几何构模，即用数字化构模表达地质体的属性，用几何构模描述地质体的空间几 何形态。那么能否构造一种模型，既能进行地质体空间几何形态的描述，又能进行其内部物理、化 学属性的表达，从而避免传统三维地质模拟方法中地质体的空间几何形态显示与内在属性分析相分 离的问题，本文的研究正是为解决这一问题而展开的。本文研究的基本思路是将体视化技术引入三 维地质模拟当中，综合应用传统的计算机图形学技术和体视化技术建立起一个地质体的体元填充模 型，这样的一个模型既表达了地质体的几何形态，又可应用三维数据场可视化算法显示地质体内的 物理、化学属性。 本文将地学体数据按照其空间分布规律分为规则体数据和非规则体数据两大类。对于地学规则 体数据的可视化，本文在分析比较了各种典型三维规则数据场可视化算法的基础上，着重研究了三 种适用于地学体数据特点的规则体数据场可视化方法，切片级重建方法、体素级重建方法及一种改 进的光线投射法。 对于地学非规则体数据的可视化，本文主要研究了非规则体数据场可视化关键技术三维约束三 角化即约束四面体化的算法原理及实现技术，包括三角化理论基础、几个经典的 Delaunay 三角化算 法等。 接下来本文研究了地质边界面与地质体体元模型的构造问题，提出按照散点数据的分区二维 Delaunay 三角化方法重构地质体边界面，并介绍了基于重构的地质边界面构造闭合的地质体边界面 的缝合算法。关于地质体体元模型的构造，论文提出将地质体闭合边界面作为约束面进行约束四面 体化来构造该模型。按照这种方法所构造出的地质体模型既可以表达地质体空间几何形态，又可表 达地质体内部物理、化学属性，为后续处理如任意方向剖切、等值面绘制等提供基础模型。 作者基于本文的研究成果并结合所在单位的实际项目进行上海地区工程地质建模试验。虽然建 立的模型还不够完善，但其给出了一个综合运用传统的计算机图形学技术及三维建模技术实现三维 地质模拟的解决方案及系统实现框架，验证了技术方案的可行性。 最后， 对本论文的研究工作做了全面总结， 指出了目前研究中存在的不足及下一步的研究方向。 关键词：体数据; 体绘制; 三维地质模拟; 地理信息系统