基于虚拟城市的三维空间模型的研究

【作者】 肖源源；

【导师】 王子牛；

【作者基本信息】 贵州大学 ， 计算机应用技术， 2008， 硕士

【摘要】 随着计算机技术和通信技术的发展,数字技术和网络技术已经给全世界带来了深刻的变化。作为信息社会的重要组成部分,数字地球、数字城市得到了迅速的发展,而虚拟城市作为可视化的平台为数字城市的运行提供了交互的界面。虚拟城市是基于虚拟现实技术和仿真模拟城市技术,是数字城市的主要表现形式。虚拟城市的研究已经成为当前研究的热点问题之一。本文主要对虚拟城市的模型设计的方法研究,并提出针对三维空间的建模方法。论文首先回顾了虚拟城市及虚拟现实技术的国内外发展现状,并就虚拟城市建设的意义进行了详细的论述。本文对虚拟城市的建模技术、环境建模、三维空间建模、空间分析等相关内容进行了研究。三维空间建模是本文研究的重点内容。对于地形的模拟,作者主要采用规则网格(Grid)和不规则三角网(TIN)两种方法对采集到的数字高程模型进行模拟,并对Delaunay三角网算法及三角网的更新算法、约束线插入算法进行了详细的论述;而对于地物的研究,作者主要讨论的是基于地理的空间建模方法,提出了三维空间的各种模型,例如TEN(不规则四面体网格)模型、Octree八叉树方法等:文章的另一个重点问题是三维空间的集成技术,由于地表模型和地物模型之间建模方式不同、数据结构的差异,模型与模型之间是几何分离的,所完成的三维空间对象模型也将是有缝隙的。针对这种情况我们提出了基于规则网格的几何无缝集成技术和基于不规则三角形网的几何无缝集成技术,并提出一种改进的地物与地形的集成方法。通过介绍了真实感实时绘制技术的两种技术:纹理映射技术和细节层次技术。纹理映射是将纹理图像贴在简单物体的几何表面,以近似描述物体表面的纹理细节,加强真实感;细节层次技术是对场景中不同物体或物体的不同部分,采用不同的细节描述方法,对于虚拟环境中的一个物体,同时建立几个具有不同细节水平的几何模型。其次,作者通过介绍windows下的OpenGL编程以及虚拟城市的再现。在建立了三维城市模型的基础上,结合真实感实时绘制方法,采用Visual C++结合三维图形应用程序接口OpenGL(开放的图形库),结合提出的模型,开发了一个初步的实验系统——虚拟城市系统,对采用该模型构建相对规则建筑物的可行性进行了论证。除此之外,在可视化的基础上实现了三维动态漫游等。文章最后对全文内容进行了总结,并提出了值得深入研究的问题。更多还原

【Abstract】 Today, with the development of computer technology and modern communication technology, great changes have taken place in the world by digital-technology and Internet technique. The digital and the digital city as most important part of information have developed rapidly, and virtual City support mutual interface as a visible platform. Virtual city is based on virtual reality technology and emulation technology, and is the merely form of expression. Nowadays, the research on virtual city is becoming one of the hottest problems. The paper is about the method of virtual city bring up the way of building model of three-dimensional space.Firstly, the paper reviewed the present situation about virtual city and virtual Reality technology and talked about the significance of building virtual city. From the paper we can see, the author mainly researched about the technology of building model, building environment model, three-dimensional space model, space analysis and so on. Building the-dimensional space model is the most important part in this paper. For the simulation of terrain, the author mainly adopted two methods Grid and TIN(triangulated irregular network) to simulate DEM and induce Delaunay triangle net algorithm, Delaunay triangle net update algorithm and constrained lines inserted algorithm to exhaust.For the object on the land, the author discussed the way of building space model based on geographical features and introduce in details different model of three-dimensional space such as TEN model, Octree model; The integration of three-dimensional space also is important problem in this paper. Gash exists in the three-dimensional space because the different of surface and object model, data structure organization and the separation of models. So we propose geometric seamless technique based on Grid and TIN and induce a new integration way to solve the problem between terrain and model under terrain. In the paper, we introduce two methods of Reality sensible and summary technology: texture mipping and level of Detail technique. Texture mipping takes image on the geometric surface of object and similar expresses the real object enhancing the sense of reality; LOD technique takes the different parts of scene into different way to describe object. For the object in the environment, we build some different detailed geometric models in the same time.Secondly, author presentetd that OpenGL programming under windows and reappear of virtual city. Under building three-dimensional city model, author combines sensible and summary drawing method and adopts visual C++, application of interface of three-dimensional image . By introduced model, we develop a simple system—virtual city system and proof it feasibility. In addition, it achieved three-dimensional dynamic roam .In the end, the paper summarized all full text and presented profound research.更多还原