【作者】 罗枫；

【导师】 叶修梓；

【作者基本信息】 浙江大学 ， 计算机应用技术， 2005， 硕士

【摘要】 随着三维网格模型技术的快速发展以及三维模型在计算机图形学、动画多媒体、虚拟动态模拟、CAD／CAM、机械以及空间布局等领域中的广泛应用，碰撞检测逐渐成为获取三维模型物理特征的主要方法之一，碰撞检测在逆向工程、动画、工程领域的应用也越来越广泛。从网格特征提取的角度看，碰撞检测是三维模型特征提取中最初的、最基本的测试过程。然而网格特征应用多样化后所带来的各种特征提取要求，给三维网格模型碰撞计算和及特征提取都带来了问题。 本文从网格模型特征提取的角度进行了研究，提出了几种比较有用的特征提取方法。同时在网格特征提取的基础上，又进一步提出了网格特征构造的方法，从而实现了网格模型碰撞时，既能进行特征提取，又能进行特征构造。这样在实际应用中，我们不仅可以通过网格特征得到网格彼此物理特性，或者继而进行相应的碰撞响应；而且可以在适当的时候构造一些需要的网格特征或网格模型。 本文通过层次树包围盒进行网格模型试探碰撞检测，然后再通过空间三角形位置特征计算判断网格体彼此的接触情况。根据层次树包围盒检测的思想，网格模型首先被OBB包围盒包住，然后逐层以间隔重叠测试方法进行判断，得到相交的包围盒；接下来对相交包围盒中的三角形进行彼此位置关系计算，产生可交三角形对和相应的三角形交线。为了解决复杂的三维网格模型碰撞过程中出现的计算问题，运用了一些优化过程 网格模型碰撞后的网格体重构，基于网格模型的特征提取。针对网格模型特征提取的特点，利用三角形对的序列关系和位置关系，实现了从三角形交线到网格相交线或相交环的构造。根据层次树包围盒的碰撞检测思想，重新提出一种可以测试相交和测试包含的包围盒包含判断算法，继而实时地判断出那些三角形处于被其他网格体包含的情况；这样结合最初特征提取出来的网格体相交三角形，可以实现网格轮廓体的重建。 在网格体特征提取和特征重构的基础上，实现了网格特征的其它一些应用，如网格特征检索，网格特征轮廓体体积估算等。更多还原

【Abstract】 With the rapid development of mesh models & their application in Computer Graphics, Animation Multimedia, Virtual Dynamic Simulation, CAD/CAM, Mechanism and spatial layout, Collision detection is receiving more and more attention and gradually becoming one of the main 3D model characters extraction. It is now widely used in reverse engineering, animation, and mechanic manufacture fields. Among the mesh character distilling methods, collision detection is a basic and initial one. However, a diversification of mesh character application usually causes kinds of character extraction, while this produce a lot of problems for collision compute and character extraction in mesh objects.From the point of character extraction of 3D mesh, this paper presents several useful distilling methods. Meanwhile we further put up mesh construction way on the base of the character extracted before, so as to achieve results on both character extraction and mesh construction. In real application, we not only get the physical idiosyncrasy through mesh character or implement corresponding collision response, but also on the right time can construct needed mesh character or mesh models.The thesis tests a hierarchical representation of models using tight-fitting oriented bounding box trees (OBBTrees), and then computes the interference detection status amongst complex models undergoing rigid motion. On the basis of bounding box detect, mesh should be wrapped in the box and be judged through interval overlap methods as to get contacted boxes. Depending on the location relation between the triangles in contacted boxes, we can calculate contacted triangles and contacted lines between contacted triangles. To minimize the compute time and complexity of collision process, optimization is also used.Mesh character conformation after contacted is base of modelscharacter extraction. In view of specialty about mesh models extraction, through the sequence and location relation between triangles contacted, contacted lines in triangle can be constructed to contacted lines or loops in mesh. From the Oriented Bounding Box collision detection point, a bounding box inclusion algorithm is developed which test contacting and including. Therefore the triangles included in the other boxes can be judged by this way. Finally, the original contacted triangles combined with the included triangles in the process can implement the mesh body reconstruction.We also present mesh character retrieve and mesh contour body volume estimation methods based on the mesh character extraction and character construction representation in further applications.更多还原