【作者】 刘牧；

【导师】 殷建；

【作者基本信息】 山东大学 ， 计算机应用技术， 2009， 硕士

【摘要】 实时三维漫游是虚拟现实领域的一个重要的研究方向,其在沉浸感、交互性与实时性综合效果方面的优势是传统平面效果图与动画技术所无法比拟的。目前,实时三维漫游技术以其特有的优势被广泛地运用于军事、娱乐、医学、地理信息系统等各领域。本文旨在研究实时三维漫游技术的关键技术,如建模、场景组织、可见性裁剪、碰撞检测等,并实现一个实时三维漫游演示系统。主要内容包括:1)研究了常用的建模技术,并比较其优缺点。介绍了三维建模工具3DS MAX的特点以及3DS文件格式及读取方式。2)对室内外场景组织方式进行了比较并着重介绍了基于BSP树的室内场景组织方式。介绍了本文采用的基于BSP树的场景组织方式,提出了回避三角形分割及回避物体分割的BSP树构建算法,树叶子节点上存储的物体用于基于视锥的可见性裁剪和第一阶段基于包围球的碰撞检测。3)讨论了常见的可见性裁剪算法,包括视锥裁剪、背面裁剪、遮挡裁剪等。提出了一种基于改进BSP树的快速视锥裁剪算法。根据BSP树中存储的物体信息,在物体级别上进行粗略的可见性裁剪,计算量小,速度快,可以有效减少需要绘制的物体数量,并利用现代图形硬件的硬件加速提高绘制速度。4)研究了碰撞检测的基本原理,提出了基于空间分割和包围球技术的双重碰撞检测算法。通过查找BSP树来确定视点所在的最小子空间。第一阶段先检测视点与物体的位置关系来进行粗略的碰撞定位,进而再对可能发生碰撞物体进行基于三角形面片的碰撞检测,提高碰撞检测的速度。本文采用三维建模工具3DS MAX建立了一个室内模型,采用VC++2005和Direct3D技术开发了一个实时三维漫游演示系统,验证了本文提出的可见性裁剪算法和碰撞检测算法的有效性。更多还原

【Abstract】 Real-time three-dimensional roaming is an important research direction in the field of virtual reality. Real-time three-dimensional Roaming has been widely used in military, entertainment, medicine, geographic information systems, etc. This paper is intended to probe into the key technologies of real-time three-dimensional roaming, including modeling, scene organization, visibility culling, collision detection and the implementation of a real-time three-dimensional roaming demo system. The main contents are as follows;1) Common modeling technologies and their advantages and disadvantages are discussed. Then introduce the Features of 3DS MAX and discuss the 3DS file format and the method of reading.2) The differences between indoor and outdoor scene organization are discussed with an emphasis on indoor scene organization based on BSP-Tree. The avoiding triangle and object partition’ s BSP-Tree building algorithm is proposed. Objects in scene are stored in leaf of BSP-Tree for visibility culling and first stage collision detection.3) Visibility culling technologies are discussed. This paper proposes a fast cone culling algorithm based on improved BSP-Tree using the objects which are stored in leaf nodes. This algorithm can fast choose objects in cone and discard the others so can rapidly reduce the objects sent to Direct3D rendering instruction.4) Basic theory of collision detection is introduced and a double stage collision detection algorithm based on space division and bounding sphere was used to accelerate the speed. First the smallest sub space is picked out and detects collision based on objects’ bounding sphere and then does accurate collision detection using object’ s triangles if needed.This paper finally sets up an indoor scene using 3DS MAX and implements a real-time 3D roaming demo system using VC2005 and Direct3D. The cone culling algorithm and collision detection algorithm we proposed are proved to be effective.更多还原