On The Lower Bound Of Edge Guards Of Polyhedral Terrains

Guarding polyhedral terrains is a relatively new problem in computational geometry. It is known as NP-hard problem. In 1997, P. Bose, T. Shermer, G. Toussaint and B. Zhu stated the bounds on the number of guards and proposed some algorithms for placing vertex and edge guards. In this contribution, we point to the inconsistency in the proof of the lower bound of the number of edge guards. We show that following the approach of Bose et al. for an n-vertex polyhedral terrain only a weaker lower bound of ?(2n?4)/7? can be achieved. Hence deriving the proof for the lower bound equal to ?(4n?4)/13? originally stated by Bose et al. remains an open issue.     

用fBm法生成山脉地形的真实感图形的方法

介绍了fBm方法的基本原理和特点,给出了在三维空间中用中点偏移法生成山脉地形数据模型的算法,提出了一种基于OpenGL山脉地形真实感显示方法,并通过实例验证其科学性和可行性。     

Planning Motions of Polyhedral Parts by Rolling

The nonholonomic nature of rolling between rigid bodies can be exploited to achieve dextrous manipulation of industrial parts with minimally complex robotic effectors. While for parts with smooth surfaces a relatively well-developed theory exists, planning for parts with only piecewise smooth surfaces is largely an open problem. The problem of arbitrarily displacing and reorienting a polyhedron by means of rotations about edges belonging to a fixed plane is considered. Relevant theoretical results are reviewed, and a polynomial time algorithm is proposed that allows planning such motions. The effects of finite accuracy in representing problem data, as well as the operational and computational complexity of the method are considered in detail. Received November 15, 1996; revised February 12, 1998.     

Using Polyhedral Models to Automatically Sketch Idealized Geometry for Structural Analysis

Simplification of polyhedral models, which may incorporate large numbers of faces and nodes, is often required to reduce their amount of data, to allow their efficient manipulation, and to speed up computation. Such a simplification process must be adapted to the use of the resulting polyhedral model. Several applications require simplified shapes which have the same topology as the original model (e.g. reverse engineering, medical applications, etc.). Nevertheless, in the fields of structural analysis and computer visualization, for example, several adaptations and idealizations of the initial geometry are often necessary. To this end, within this paper a new approach is proposed to simplify an initial manifold or non-manifold polyhedral model with respect to bounded errors specified by the user, or set up, for example, from a preliminary F.E. analysis. The topological changes which may occur during a simplification because of the bounded error (or tolerance) values specified are performed using specific curvature and topological criteria and operators. Moreover, topological changes, whether or not they kept the manifold of the object, are managed simultaneously with the geometric operations of the simplification process.     

Polyhedral representation of fuzzy linear bases

 In [15], we introduced the concepts of fuzzy bases, fuzzy linear interpolation and fuzzy polygon of four-component fuzzy linear bases. In [16], these concepts were used in the maximal profile of the set of polygons generated from a set of break points for each variable dimension. Theconcept was operationalized in a fuzzy linear basis algorithm (FLBA) for nonlinear separable programming problems involving no more than a finite number of discontinuities. The FLBA provides a powerful platform forparallel processing of the fuzzy linear sub-problems included in the finite FLB-chain. In this paper we extend the theory of fuzzy linear bases from the set of polygons toapolyhedral representation of four-component fuzzy linear bases defined on a closed subset of the real line.     

基于独立环路组合的多面体视图三维重建

提出了一种基于平面独立环路组合的多面体视图三维重建完整算法，即先把三视图中的每个视图分解成一个个独立的不可再分的平面独立环路，然后从三面视图的三个环路组中逐个取出可能的环路组合按构造实心体几何方法（CSG）构成局部实心体模型，最后将局部实心体模型组合成整体实心体模型。已按上述算法编制出了能在Auto CAD图形系统中使用的实用软件。     

一种基于几何特征的改进模板匹配算法

在线视觉棒材计数系统通过实时处理视频信息对运动对象进行计数，为了满足实时性行要求，本文提出一种基于几何特征的快速模板匹配算法，实验表明该算法能有效地识别出棒材目标，并显著提高了速度。     

一种基于几何特征的改进模板匹配算法

在线视觉棒材计数系统通过实时处理视频信息对运动对象进行计数,为了满足实时性行要求,本文提出一种基于几何特征的快速模板匹配算法,实验表明该算法能有效地识别出棒材目标,并显著提高了速度。     

指纹特征点匹配算法探析

指纹形变问题已成为指纹鉴别准确率的瓶颈。本文针对指纹的形变问题,对现行的指纹特征点匹配算法进行了研究和探讨,提出了一种能够实现精确匹配的特征点匹配算法,从而有效地解决指纹变形等问题。     

一种新的二维开曲线匹配算法研究

在提取碎片轮廓的基础上,提出了一种基于相似变换下的新的尺寸不变为标示符的二维开曲线匹配方法。基本思想是首先以弧长的曲率绝对值的积分方法,通过对轮廓重采样来计算轮廓曲线上的特征点,特征点分曲线为若干段,然后特征段之间的Hausdorff距离来比较两曲线的段的相似性,当Hausdorff距离小于给定的容差时,可认为相应的轮廓是匹配的,实验证明算法更快有效。     

一种面向Web服务的语义匹配方法

本文针对语法匹配带来的不足提出了一种新的语义匹配方法。     

支持防火墙规则扩展的匹配算法HERAM

防火墙是一种重要的网络安全技术,但随着网络规模的发展,遇到了许多急需解决的问题,其中就有防火墙网络瓶颈的问题。提出一种新的规则匹配算法来解决这个问题,把多维的问题进行降维处理,根据规则之间有无关联性把规则进行分类处理,另外把新添加的规则运用散列表进行组织,从而做到在增加扩展性的同时,使时间效率不受大的影响。     

基于细节点方向分布的指纹特征匹配

提出了一种新的指纹细节点匹配算法。该算法首先基于细节点方向分布特性将指纹在旋转方向上对齐,减少了大量的旋转操作,然后利用大小变化的界限盒判定细节点之间的对应关系。该算法不受指纹之间旋转变形、平移变换和非线性变形的影响,也不受细节点提取误差的影响。实验结果表明该算法不仅处理速度较快,而且具有令人满意的精度。     

树匹配算法在网页分类中的应用

本文主要研究了树匹配算法在网页分类中的应用。在详细地介绍树匹配算法后。通过实验证明了该方法的有效性。     

指纹细节匹配中细节点方向算法研究

本文提出了一种指纹图像匹配中细节点方向的计算方法,这种算法利用细节点所在的纹线来计算细节点的方向,实验结果表明,此算法对计算指纹图像细节点方向是有效的。     

特征脸和弹性匹配人脸识别算法的比较

计算机自动人脸识别技术是模式识别的一个重要分支,有着广泛的应用背景。特征脸和弹性匹配是两种主要的人脸识别算法。该文研究了视角、表情、光照等变化对两种算法的影响并对此时两种算法的性能进行了比较,理论分析和实验结果都表明此时弹性匹配的识别率优于特征脸。     

面向入侵检测的改进BM模式匹配算法

网络入侵检测系统的效率取决于模式匹配算法选择.分析了目前网络上常用的BM算法及其不足,提出了一种更高效的改进算法.该算法利用模式串自身的特点,能有效地减少字符重复比较的次数,并利用位置移动表代替BM算法中的好后缀和坏字符移动表,提高了算法的匹配效率.实验结果表明,改进的模式匹配算法能够有效提高网络入侵检测系统的检测速度...     

基于索引模板匹配替换通用算法的机器翻译

索引模板匹配替换通用算法能够自动快速地从模板对应规则库找到与英语句子中相匹配的英语模板,并将其替换成相对应的汉语模板。以该算法为基础的英汉翻译系统能够合理地综合基于规则和基于例子的翻译系统的优点,同时能够在一定程度上克服它们的缺点。速度测试表明,该该英汉翻译系统在P—IV1.7G的计算机上的翻译速度每秒可以达到1300个单词左右;质量测试表明,该系统具有较好的发展潜力。     

一种匹配Z变换的零点匹配方法

匹配Z变换是将模拟控制器变为数字控制器的一种数字化方法，若模拟控制器的复数零点的虚部ω0大于采样角频率ω8的一半，这时数字控制器的频率特性将会产生严重混叠。本文针对这个问题进行了研究，提出了一种零点匹配方法。     

基于模板匹配的机器视觉话机检测系统

针对流水线产品的自动检测需求的不断提升,使用模板匹配算法实现智能话机检测设备．并进行软件仿真,该系统用于检测话机按键的错装、漏装以及字符印刷错误等问题,实时获取产品图像和检测产品,可视化效果好。