检索结果-内蒙古大学图书馆

Interpolation by geometric algorithm

COMPUTER-AIDED DESIGN 2007年第4期39卷 313-323页

作者： Maekawa, Takashi Matsumoto, Yasunori Namiki, Ken Yokohama Natl Univ Dept Mech Engn Yokohama Kanagawa 2408501 Japan

We present a novel geometric algorithm to construct a smooth surface that interpolates a triangular or a quadrilateral mesh of arbitrary topological type formed by n vertices. Although our method can be applied to B-spline surfaces and subdivision surfaces of all kinds, we illustrate our algorithm focusing on Loop subdivision surfaces as most of the meshes are in triangular form. We start our algorithm by assuming that the given triangular mesh is a control net of a Loop subdivision surface. The control points are iteratively updated globally by a simple local point-surface distance computation and an offsetting procedure without solving a linear system. The complexity of our algorithm is O(mn) where n is the number of vertices and at is the number of iterations. The number of iterations m depends on the fineness of the mesh and accuracy required. (c) 2007 Elsevier Ltd. All rights reserved.

关键词： geometric algorithm surface interpolation loop subdivision surface Catmull-Clark subdivision surface B-spline curves and surfaces geometric modeling

来源：评论

学校读者我要写书评

暂无评论

Precise Hausdorff distance computation between polygonal meshes

引用

COMPUTER AIDED geometric DESIGN 2010年第8期27卷 580-591页

作者： Barton, Michael Hanniel, Iddo Elber, Gershon Kim, Myung-Soo Technion Israel Inst Technol IL-32000 Haifa Israel SolidWorks Corp Concord MA 01742 USA Seoul Natl Univ Seoul 151744 South Korea

We present an exact algorithm for computing the precise Hausdorff distance between two general polyhedra represented as triangular meshes. The locus of candidate points, events where the Hausdorff distance may occur, is fully classified. These events include simple cases where foot points of vertices are examined as well as more complicated cases where extreme distance evaluation is needed on the intersection curve of one mesh with the medial axis of the other mesh. No explicit reconstruction of the medial axis is conducted and only bisectors of pairs of primitives (i.e. vertex, edge, or face) are analytically constructed and intersected with the other mesh, yielding a set of conic segments. For each conic segment, the distance functions to all primitives are constructed and the maximum value of their low envelope function may correspond to a candidate point for the Hausdorff distance. The algorithm is fully implemented and several experimental results are also presented. (C) 2010 Elsevier B.V. All rights reserved.

关键词： Hausdorff distance Polygonal mesh geometric algorithm Bisector surface Medial axis Low envelope

来源：评论

学校读者我要写书评

暂无评论

Precise Hausdorff distance computation between polygonal meshes

Precise Hausdorff distance computation between polygonal mes...

引用

Conference on Geometry - Theory and Applications

作者： Barton, Michael Hanniel, Iddo Elber, Gershon Kim, Myung-Soo Technion Israel Inst Technol IL-32000 Haifa Israel SolidWorks Corp Concord MA 01742 USA Seoul Natl Univ Seoul 151744 South Korea

关键词： Hausdorff distance Polygonal mesh geometric algorithm Bisector surface Medial axis Low envelope

来源：评论

学校读者我要写书评

暂无评论

Point-tangent/point-normal B-spline curve interpolation by geometric algorithms

引用

COMPUTER-AIDED DESIGN 2009年第6期41卷 412-422页

作者： Gofuku, Shu-ichi Tamura, Shigefumi Maekawa, Takashi Yokohama Natl Univ Dept Mech Engn Digital Engn Lab Yokohama Kanagawa Japan

We introduce a novel method to interpolate a set of data points as well as unit tangent vectors or unit normal vectors at the data points by means of a B-spline curve interpolation technique using geometric algorithms. The advantages of our algorithm are that it has a compact representation, it does not require the magnitudes of the tangent vectors or normal vectors, and it has C-2 continuity. We compare our method with the conventional curve interpolation methods, namely, the standard point interpolation method, the method introduced by Piegl and Tiller, which interpolates points as well as the first derivatives at every point, and the piecewise cubic Hermite interpolation method. Examples are provided to demonstrate the effectiveness of the proposed algorithms. (C) 2009 Elsevier Ltd. All rights reserved.

关键词： Interpolation Point-normal interpolation Point-tangent interpolation geometric algorithm B-spline curve

来源：评论

学校读者我要写书评

暂无评论

A geometric method for model selection in support vector machine

引用

EXPERT SYSTEMS WITH APPLICATIONS 2009年第3期36卷 5745-5749页

作者： Peng, Xinjun Wang, Yifei Shanghai Normal Univ Dept Computat Math Shanghai 200234 Peoples R China Shanghai Univ Dept Math Shanghai 200444 Peoples R China

Support vector machine (SVM) has become one of the most popular methods in machine learning during the last years. The parameters' selection in SVM is an important step in achieving a high performance learning machine. Some methods are proposed by minimizing an estimate of generalization error based on bound of leave-one-out (LOO) bound, empirical error, etc. These methods have to optimize many quadratic programming problems and compute an inversion of the Gram-Schmidt matrix, which cause to be time-consuming in large-scale problems. This paper introduces a fast incremental method to optimize the kernel parameters in SVM by combining a geometric algorithm on SVM and an approximation of the gradient of the empirical error. This method shows an online way to update the kernel parameters and work set in incremental learning, which reduces the resources required both CPU time and storage space. The numerical tests on some benchmarks confirm our method. Crown Copyright (C) 2008 Published by Elsevier Ltd. All rights reserved.

关键词： Support vector machine Model selection Parameter geometric algorithm Optimize

来源：评论

学校读者我要写书评

暂无评论

WIRE ELECTRICAL DISCHARGE MACHINING (WEDM) AS A SUBTRACTIVE RAPID MANUFACTURING TOOL

WIRE ELECTRICAL DISCHARGE MACHINING (WEDM) AS A SUBTRACTIVE ...

引用

作者： Yang, Zhi PennState University Libraries

学位级别：Doctor of Philosophy

A modern Wire Electrical Discharge Machining (WEDM) system is capable of producing more complex geometry than 2D, 2½D or ruled surface parts. The improved geometric capability and the other well-known advantages, such as capability of cutting hard materials, ignorable cutting force, make WEDM a potential Rapid Prototyping (RP) process. Unfortunately, limited capability in process planning automation for six-axis WEDM requires significant process planning time and *** research presents the development of a methodology and the associated algorithms for using WEDM as a subtractive rapid prototyping process. Specifically, an automatic process planning system is built for six-axis WEDM process. A boundary representation is used to model part geometry and the manufacturability of a part on a six-axis WEDM machine is addressed in this research as well. In particular, a stereolithography (STL) file is used as the input for the algorithms. Global tangent visibility, fabrication orientation, and the setup requirements and numerical control code are the *** to the importance of visibility analysis in the automation of the milling process planning, global tangent visibility analysis is the foundation in the automation of WEDM process planning. In this research, an algorithm to calculate the global tangent visibility for polyhedral computer-aided design (CAD) models was developed. A greedy algorithm is also developed to classify the global visibility results and to determine the setup plans for producible geometries on six-axis WEDM. Number of setup orientations is determined automatically for six-axis WEDM machines. A method to generate machine instructions automatically based on tangent visibility results and setup plans was also developed. In order to verify the methodology, a verification system is built; and several sample parts are fabricated. The methodology and algorithms developed in this research result in a systematic automatic process planning meth

关键词： Visibility Analysis Wire EDM Computer-aided Manufacturing Rapid Manufacturing Process Planning geometric algorithm

来源：评论

学校读者我要写书评

暂无评论

A novel geometry-based feature-selection technique for hyperspectral imagery

引用

IEEE GEOSCIENCE AND REMOTE SENSING LETTERS 2007年第1期4卷 171-175页

作者： Wang, Liguo Jia, Xiuping Zhang, Ye Harbin Inst Technol Dept Informat Engn Harbin 150001 Heilongjiang Peoples R China Univ New S Wales Univ Coll Sch Informat Technol & Elect Engn Australian Def Force Acad Canberra ACT 2600 Australia

In this letter, a geometry-based feature-selection method is proposed for efficient analysis of hyperspectral imagery. It searches the vertices that form the largest simplex iteratively in pixel space. These vertices are representative subsets of spectral bands. A distance measure is introduced in the simplex volume comparison for fast implementation of the proposed method. Fast principal component analysis and spectral band indexing are suggested for data preprocessing. This method can be implemented in supervised or unsupervised manner. It is automatic, fast, and distribution-free. Experimental results show the superiority of the proposed method in terms of quality and speed.

关键词： feature selection (FS) geometric algorithm hyperspectral imagery (HSI)

来源：评论

学校读者我要写书评

暂无评论

Optimal geometric algorithms for digitized images on arrays with reconfigurable optical buses

引用

MICROPROCESSORS AND MICROSYSTEMS 2006年第7期30卷 425-434页

作者： Wu, Chin-Hsiung Horng, Shi-Jinn Wang, Yuh-Rau Tsai, Horng-Ren Shih Chien Univ Dept Informat Technol & Commun Kaohsiung Taiwan Natl Taiwan Univ Sci & Technol Dept Comp Sci & Informat Engn Taipei Taiwan St Johns Univ Dept Comp Sci & Informat Engn Taipei Taiwan Ling Tung Univ Dept Informat Technol Taichung Taiwan

geometric algorithms play an important role in computer graphics and digital image analysis. This paper makes an improvement of computing geometric properties of labelled images using arrays with reconfigurable optical buses (AROB). For an N x N image, we first design two constant time algorithms for computing the leftmost one problem and for the component reallocation problem. Then, several geometric algorithms for the labelled images are derived. These include finding the border pixels, computing the perimeter and area, computing the convex hull, determining whether two figures are linearly separable, computing the smallest enclosing box, solving the nearest neighbor problems, and computing the width and diameter. The major contribution of this work is to design both time and cost optimal algorithms for these problems. To the best of our knowledge, the proposed algorithms are the first constant time algorithms for these problems on the labelled images. (C) 2006 Elsevier B.V. All rights reserved.

关键词： geometric algorithm reconfigurable optical buses pattern recognition digital geometry image labelling

来源：评论

学校读者我要写书评

暂无评论

geometric Properties of Ribs and Fans of a Bézier Curve

引用

Journal of Computer Science & Technology 2006年第2期21卷 279-283页

作者： Joo-Haeng Lee Hyungjun Park Electronics and Telecommunications Research Institute Daejeon 305-350 Korea Chosun University Gwangju 501-759 Korea

Ribs and fans are interesting geometric entities that are derived from a given Bézier curve or surface based on the recent theory of rib and fan decomposition. In this paper, we present some of new geometric properties of ribs and fans for a Bézier curve including composite fans, rib-invariant deformation, and fan-continuity in subdivision. We also give some examples for the presented properties.

关键词： geometric algorithm Bézier curve composite fan rib-invariance fan-continuity

来源：评论

学校读者我要写书评

暂无评论

Digital Differential Geometry Processing

引用

Journal of Computer Science & Technology 2006年第5期21卷 847-860页

作者：刘新国鲍虎军彭群生 State Key Lab of CAD& CG Zhejiang University Hangzhou 310027 P.R. China

The theory and methods of digital geometry processing has been research area in computer graphics, as geometric models serves as the core data for 3D graphics applications. The purpose of this paper is to introduce some recent advances in digital geometry processing, particularly mesh fairing, surface parameterization and mesh editing, that heavily use differential geometry quantities. Some related concepts from differential geometry, such as normal, curvature, gradient, Laplacian and their counterparts on digital geometry are also reviewed for understanding the strength and weakness of various digital geometry processing methods.

关键词： digital geometry geometric algorithm mesh editing Laplacian parameterization

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：