虚拟现实系统中基于CAD数据的高效建模方法研究.pdf

南京航空航天大学
硕士学位论文
虚拟现实系统中基于CAD数据的高效建模方法研究
姓名:于倩
申请学位级别:硕士
专业:安全技术及工程
指导教师:顾宏斌
2011-01
南京航空航天大学硕士学位论文
摘要
当前基于 CAD 模型的虚拟现实建模方法存在模型面片数量过多或者容易产生狭长、病态
的三角形、易丢失边界特征等不足,因此难以满足虚拟现实系统实时渲染以及视觉上的需求。
本课题提出一种将 CAD 模型简化和转换后应用于虚拟系统的方法,首先将已有的 CAD 模
型导出为中间格式并进行解析得到网格数据,然后利用一种新的基于分类的自适应简化算法对
网格进行多分辨率简化处理,即先按照网格模型的特点进行分类,在分类的基础上再进行针对
性的简化。把经过简化后的三维模型加上材质和纹理后写成工业标准的 OpenFlight 格式,最后
在视景实时管理系统 VegaPrime 中对用上述方法生成的模型进行可视化漫游,仿真获得较为逼
真满意的效果,表明上述方法是行之有效的。
从虚拟现实建模的角度出发,根据视景建模的需求结合我们的现有条件和已存在的一些开
发工具开发了一种根据已有的产品 CAD 模型快速生成满足虚拟现实视景要求的 OpenFlight 模
型的系统。该系统在 VC 平台下,用 C++、OpenGL 和 OpenFlight API 编程实现。经过在虚
拟环境中的测试验证了该模型能更好的满足实时渲染要求,同时视觉效果也更加合理。


关键词: 虚拟现实;CAD 模型;模型转换;分类算法;网格简化;
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虚拟现实系统中基于 CAD 数据的高效建模方法研究
Based on the sorting algorithm of transform from CAD to VR
model
Abstract: Nowadays, Due to too many polygon faces or Irregular triangles as well as losing
boundary information were produced when CAD model converts to virtual reality model, it could not
meet the requirement of real time rendering in virtual reality environment.
A method about CAD model's translation and simplification was introduced. The CAD model
was exported to the media file and then the mesh data which got from media file was simplified
through the sorting algorithm. At last the standard model of virtual reality was created by OpenFlight
API. The whole simulator model has been walked in VegaPrime runtime environment. The
visualization simulation has achieved a satisfying result, so this method put forward in this paper is
valid and effective.
From the viewpoint of Virtual Reality Modeling, in accordance with light Flight simulator view
modeling bined with our existing conditions and a number of development tools,
develop a system which could generate OpenFlight model meeting virtual reality view requirement
rapidly in accordance with the existing CAD models. This paper carries out in-depth research on
three-dimensional mesh simplification algorith