A Coherence-based Collision Detection Method for Dressed Human Simulation

In this paper, paper we present a coherence-based method to detect collisions between the garment and human model for dressed human simulations. Based on the property of coherence, collisions can be rapidly detected by tracking the movement of the most likely geometric elements to collide. The voxel technique is employed to quickly identify the potential collision region. Experimental results show that our method is very efficient.     

复杂实体干涉检验的改进八叉树法

在基于结构立体几何的实体造型系统中，用改进的八叉树方法进行了复杂实体间的干涉检验，即避免了复杂实体间的求交运算，又很好地克服了传统八叉树方法精度低的缺点。本文提出的方法可以推广至机器人无碰路径规划，三维实体布局等所有需要进行干涉检验的领域。     

A collision resolution algorithm for clump-free fast moving cloth

Cloth animation is an important area of computer graphics due to its numerous applications. However, so far a fast moving cloth with multiple wrinkles has been difficult to animate because of the cloth clump problem. Cloth clumps are the frozen areas where cloth pieces are clustered unnaturally — an obstacle in making a realistic cloth animation. Hence we present a novel cloth collision resolution algorithm that prevents clump formation during fast cloth motions. The goal of our resolution algorithm is to make cloth move swiftly without having any unnatural frozen cloth clumps, while preventing any cloth-cloth and rigid-cloth penetrations at any moment of a simulation. The non-penetration status of cloth is maintained without the formation of cloth clumps regardless of the speed of cloth motion. Our algorithm is based on a particular order that we found in the resolution of cloth collisions, and can be used with any structural modeling approaches such as spring-masses or finite elements. This paper includes several realistic simulation examples involving fast motions that are clump-free.     

虚拟坦克装甲车运动仿真中的碰撞检测算法研究

提出了一种新的虚拟坦克装甲车运动仿真的混合碰撞检测算法,该算法是先用帧与帧之间的画面连贯性进行判断,若帧与帧之间的物体不一致,则用方向包围盒来进行碰撞检测,为了避免两帧之间发生穿透,则有线段与包围盒的重叠测试进行穿透测试。此算法可以很好解决坦克装甲车的运动仿真中的碰撞检测。满足实时性要求。     

一种基于图像的刚体碰撞检测

本文针对3D运动模拟,详细讨论了在OpenGL中利用模板测试和深度测试进行碰撞检测的原理和方法。这种基于图像空间的碰撞检测方法,充分利用了图形硬件的性能并有效地降低了CPU的计算负担。     

车辆碰撞检测的一种简化数学模型

该文建立了车辆碰撞检测的一种简化数学模型,并进行了仿真验证。实际应用结果表明本模型具有简单和计算快捷的特点,能满足车辆碰撞检测的仿真要求。     

织物仿真中的冲突检测和处理

冲突检测以及冲突处理一直是织物仿真的“瓶颈”问题。该文论述了对柔性物体如织物与刚体的冲突检测问题。通过正冲突物体表面周围建立一个很狭小的相当于防护屏的力场来避开冲突。将这个力场分割成一些连续不重迭的完全围绕着表面的小单元,一旦某个点要进入某个单元,就产生一个排斥力,这个力的大小和方向由速度、法向、点与表面的距离决定。     

虚拟现实在变电站仿真中的应用

虚拟环境就是采用以计算机技术为核心的现代高科技生成逼真的三维环境,是对现场环境的最真实仿真.该系统基于OSG1.0开发库,利用3DMax建模工具构建模型场景,VC 和OSG编程来实现场景的显示、场景的漫游、碰撞检测和设备的状态变化,构筑一个三维、动态、实时、可交互的数据平台, 展现包含各种数据的动态的实体效果.用户可以自然地和虚拟环境中的客体进行交互,相互影响,从而产生亲临现场的感受和体验.最终该系统满足了变电站仿真培训的要求.     

基于图像空间的刚体碰撞检测的OpenGL实现

本文针对三维场景的的运动模拟,详细讨论了在OpenGL中利用摸板测试和深度测试进行碰撞检测的原理和方法.这种基于图像空间的碰撞检测方法,充分利用了图形硬件的性能并有效地降低了CPU的计算负担.由于充分结合了OpenGL的操作特点,因此本文具有一定的实践意义.     

Efficient emulation of single-hop radio network with collision detection on multi-hop radio network with no collision detection

Summary This paper presents an efficient randomized emulation ofsingle-hop radio networkwith collision detection onmulti-hop radio networkwithout collision detection. Each step of the single-hop network is emulated by rounds of the multi-hop network and succeeds with probability 1–. (n is the number of processors,D the diameter and the maximum degree). It is shown how to emulate any polynomial algorithm such that the probability of failure remains . A consequence of the emulation is an efficient randomized algorithm for choosing a leader in a multi-hop network. Reuven Bar-Yehuda was born in Iran, on July 17th 1951. Received B.A., M.Sc., and D.Sc. in Computer Science from the Technion — Israel Institute of Technology, Haifa, Israel, in 1978, 1980, and 1983, respectively. He is currently a Senior Lecturer of Computer Science at the Technion. From 1984 to 1986, he was a visiting assistant professor in the Computer Science Dept. at the Duke Univesity His research interests include computational geometry, VLSI, graph algorithms and distributed algorithms. Oded Goldreich was born in Tel-Aviv, Israel, on February 4th 1957. Received B.A., M.Sc., and D.Sc. in Computer Science from the Technion — Israel Institute of Technology, Haifa, Israel, in 1980, 1982, and 1983, respectively. He is currently an Associate Professor of Computer Science at the Technion. From 1983 to 1986, he was a postdoctoral fellow at MIT's Laboratory for Computer Science. His research interests include cryptography and related areas, relation between randomness and algorithms, and distributed computation. Alon Itai was born in Scotland, on December 12th 1946. Received B.Sc. in Mathematics from the Hebrew University in Jerusalem in 1969. M.Sc., and Ph.D. in Computer Science from the Weizmann Institute of Science, Rehovot, Israel in 1971 and 1976. He is currently an Associate Professor of Computer Science at the Technion. His research interests include randomized and distributed algorithms, computational learning theory and performance evaluation.The second author was partially supported by grant No. 86-00301 from the United States—Israel Bi-national Science Foundation BSF), Jerusalem, Israel.     

Parallel collision detection of ellipsoids with applications in large scale multibody dynamics

This contribution describes a parallel approach for determining the collision state of a large collection of ellipsoids. Collision detection is required in granular dynamics simulation where it can combine with a differential variational inequality solver or discrete element method to approximate the time evolution of a collection of rigid bodies interacting through frictional contact. The approach proposed is structured on three levels. At the lowest level, the collision information associated with two colliding ellipsoids is obtained as the solution of a two-variable unconstrained optimization problem for which first and second order sensitivity information is derived analytically. Although this optimization approach suffices to resolve the collision problem between any two arbitrary ellipsoids, a less versatile but more efficient approach precedes it to gauge whether two ellipsoids are actually in contact and require the more costly optimization approach. This intermediate level draws on the analytical solution of a 3rd order polynomial obtained from the characteristic equation of two arbitrary ellipsoids. Finally, this intermediate level is invoked by the outer level only when a 3D spatial binning algorithm indicates that two ellipsoids share the same bin (box) and therefore could potentially collide. This multi-level approach is implemented in parallel and when executed on a ubiquitous Graphics Processing Unit (GPU) card scales linearly and yields a two orders of magnitude speedup over a similar algorithm executed on the Central Processing Unit (CPU). The GPU-based ellipsoid contact detection algorithm yields a 14-fold speedup over a CPU-based sphere contact detection algorithm implemented in the third party open source Bullet Physics Library (BPL). The proposed methodology provides the efficiency demanded by granular dynamics applications, which routinely handle scenarios with millions of collision events.     

碰撞检测技术在空间飞行器视景仿真中的应用

视景仿真技术是空间飞行器系统仿真中的关键技术之一。该文阐述了碰撞检测技术在视景仿真中的应用,旨在提高飞行器视景仿真的逼真度。文中列述了视景驱动软件Vega的8种碰撞检测方法,分析了各种方法的特点,并展示了各种碰撞检测方法应用于空间飞行器视景仿真中的结果,包括卫星星下点轨迹绘制、卫星照相效果显示等,从而证实了将碰撞检测技术应用于空间飞行器视景仿真能取得良好的仿真效果。该文为空间飞行器视景仿真以及碰撞检测技术应用者提供了应用范例,具有一定借鉴价值。     

基于并行的快速碰撞检测算法的研究

为了提高检测速度,提出了一种基于并行的快速碰撞检测算法,该算法首先将任意多面体的剖分为多个四面体,然后对四面体进行并行碰撞检测,并通过建立包围盒树进一步提高算法的效率,并行算法采用基于MPI库方式来实现.结果表明,该算法显著提高检测速度并具备较高精度.     

基于DDA的碰撞检测及碰撞仿真

碰撞检测是基于物理的动画,计算机辅助没计,计算机辅助制造,计算几何,虚拟现实,机器人等领域必须解决的关键问题,目前仍是研究热点.非连续变形分析方法是一种较新的土木工程领域的数值模拟技术,可以分析不连续块体的运动.将非连续变形分析方法引入到基于物理动厕领域.在计算辅助设计软件设计的虚拟物理场景下,仿真了汽车撞墙和车辆相撞.仿真结果显示:应用非连续变形分析方法可以成功的实现精确的碰撞检测和模拟真实的碰撞响应,在不连续变形、多块体碰撞仿真方面有较大优势.     

面向对象碰撞检测方法及其在分布式虚拟环境中的应用

本文提出了一种面向对象的碰撞检测方法,分析了这种碰撞检测方法的时间复杂性,讨论了分布式环境中碰撞检测的完全性和唯一性等问题,提出了一种保证分布式虚拟环境中碰撞检测唯一性的方法,最后,讨论了这种方法在分布式虚拟环境ＤＶＥＮＥＴ中的应用。     

Algorithms for the physical rendering and assembly of octree models

Hierarchical decomposition techniques are well established for the representation of 2D images, the calculation of distance maps, and the modelling of volume data. However, recent work has suggested that their use can be extended to the manufacture of physical objects for low cost prototyping and visualization. This paper details various decomposition and assembly planning routines created to support this process. Specifically the decomposition methods are described to generate octants appropriate for the physical assembly process. Having established methods for generating suitable octrees, three different algorithms for planning the assembly of octrees are presented. The comparative performance of these different approaches is discussed.     

实时碰撞检测算法的探讨与研究

本文对碰撞检测算法的分类进行了阐述,并比较了按层次包围盒法分类的包围盒AABB、包围球、方向包围盒OBB、固定方向凸包的包围盒FDH、时空包围盒检测算法（STBB）的构造难度高低,存储量大小和相交测试复杂度高低等方面。同时,也对空间分割法下的各类算法进行了分析。最后介绍了两种新趋势下的混合碰撞检测法进行了归纳研究,并总结了算法的优劣和新的方向。