【作者】 张正军；

【导师】 吴慧中；

【作者基本信息】 南京理工大学 ， 计算机应用， 2002， 博士

【摘要】 在计算机图形学研究领域，不规则物体的真实感图形生成技术一直是最具有活力、最具有挑战性的研究方向之一。其中，虚拟物体爆炸效果的真实感图形生成技术更是具有难度的研究课题。本文结合国防科工委下达的“九·五”国防重点预研课题“三维实时图象生成和显示技术”，在虚拟壳体爆炸建模的理论与方法方面进行深入的研究和探讨，较为系统地研究了虚拟壳体爆炸过程建模的数据结构、壳体爆炸过程模拟的一般理论方法和具体实现技术，较为详细地给出了各种实现算法。论文所做的主要工作和研究成果如下： (1)详细地介绍了半边数据结构中各个节点之间的相互关系，着重讨论了半边节点与其它节点之间的关系。在此基础上，提出了随机半边数据结构，并详细分析了随机半边数据结构中半边节点的随机属性，并给出了随机属性的具体含义。 (2)针对半边数据结构表示的物体原模型，提出了物体爆炸时构造破片的理论方法，称之为随机分类构造法。同时提出了面片之间的连结关系和等价关系的概念。分析了物体爆炸的机理，提出了关于物体爆炸的几个合理假设。在此基础上，得到了一些有关破片的性质。根据随机分类构造法构造破片的模型，并应用于两种简单的爆炸模型：等可能破裂模型和均匀预制破片模型。 (3)在深入探讨爆炸模型的构造和实时显示的基础上，提出了隐式破片、显式破片的最新概念和两种生成破片的方法：小面片等价法和面片集封闭法，并给出了三个实用的算法：虚拟实体的微粒化算法、小面片等价算法和面片集封闭算法，并对小面片等价法和面片集封闭法及其算法进行了比较。同时对小面片等价法和面片集封闭法这两种方法在实体破裂过程中的运用进行了探讨，对实际模拟运行的时间进行了测量和对照。 (4)针对实体的三维特性，提出了一种新的描述三维实体的数据结构——半面数据结构，论文分析了半面数据结构中各节点之间的相互关系，并提出了半边结构转化为半面结构的方法，分别称为边界切割法、微粒收缩法、边界包围法和包围边界法。同时提出了半面结构转化为半边结构的对偶面片湮灭法。 (5)基于半面数据结构，提出了一种新的随机分类构造法和两种生成实体破片的方法。并进一步通过实例对破片生成的方法的可行性、破片的三维特性以及破片的随机性进行了应用验证。 (6)提出了一个适合于虚拟弹体爆炸的具有运动特征的随机半边数据结构，并在爆炸力学的基础上，根据爆炸的相关特征构造出虚拟弹体爆炸过程中三个阶段的模型：弹体的膨胀模型、弹体的破裂模型以及破片的运动模型。同时，利用这三个模型给出了虚拟摘要博.比丈弹体整个爆炸过程的具体算法。 (刀从爆炸的机理出发，利用合理的假设，将壳体的爆炸过程处理为马尔可夫过程，把爆炸的机理同爆炸的随机性联系在一起，建立了壳体爆炸的两种模型:仿真模型和简化模型，提出了破裂程度的倍密度函数和破裂方向的倍密度函数两个概念，得到了基于半边结构的虚拟壳体爆炸过程中任一条边出现裂缝的概率公式。更多还原

【Abstract】 Technique of generating realistic graphics especially for those irregular objects is one of the most challenging, active subjects in computer graphics. Moreover, generating the realistic graphics of the explosion of virtual object is more challenging. Based on the subject named "3D Real-time Image Generation and Display", which is one of the vital research subjects of the nine fifth-year plan established by the committee of national defense science and industry, the paper firstly researches on modeling theories and methods of virtual shell explosion, then discusses the data structure for modeling on virtual shell explosion roundly, and advances the general methods and detailed implementations of simulating on shell explosion process. The primary work and remarks of the paper are:(1) The paper introduces the correlations among nodes of half-edge data structure in detail, and takes an emphasis on discussing the correlations between half-edge node and other nodes. It presents the concept called stochastic half-edge data structure, discusses the stochastic attribute and its idiographic signification in a half-edge node.(2) Based on the object prototype represented by half-edge data structure, the paper presents a method to construct fragments in explosion, which is called random-classification construction method. This method is especially satisfying when applied on two simple model of fragment, namely equality probability breaking model and uniformity prefabrication fragment model. And the paper presents the concepts about conjunctive relation and equivalent relation among facets. The paper analyses the explosion mechanism of objects and presents some reasonable assumptions about explosion, then several properties about fragment construction can be deduced.(3) The paper firstly brings forward the concepts of concealed fragment, apparent fragment. It also advances two fragment generation methods: facet equivalence method and facet set enclosing method, and realizes three practical algorithms: the first one is to make a virtual entity particulate, the second is facet equivalence algorithm, the last is seed facet set enclosing algorithm. The paper analyzes and compares the last two methods and related algorithms, researches on applying the two methods to the break process of a virtual entity.(4) The paper proposes a new data structure especially for representing three-dimension objects called half-facet data structure, which provides a firm foundation for further research on modeling of irregular objects. In this paper, the connections among all nodes are given and fourmethods of transforming half-edge data structure into half-face data structure are presented. These methods are facet cutting method, particulates contracting method, facets enveloping method and enveloping objects method. At the same time half-facet data structure can be transformed using the dual facet annihilating method.(5) The paper presents a new random-classification construction method based on half-facet data structure. The application verifies the feasibility of the methods generating fragments, 3D characteristic of fragments and the stochastic characteristic of fragments.(6) The paper advances a data structure that is suitable for the simulation of bomb explosion. The data structure is called stochastic half-edge data structure with motion characteristics. By considering the mechanics and the correlative characteristics of the explosion, the paper constructs three models corresponding to the three phases during an explosion. They are expanding model of the bomb body, bursting model of the bomb body and motion model of the fragments. According to the models, the paper gives a detailed algorithm for the whole process of the bomb explosion.(7) Based on the explosion mechanism and the stochastic characteristic of the shell, the paper advances some reasonable hypotheses and supposes that the explosion process of the shell is a Markov process, thus constitutes two explosion models of the shell: the imitation model an更多还原