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Proceedings of the 2001 ACM International Symposium on Mobile Ad Hoc Networking and Computing: MobiHoc 2001

作者： Gao, Jie Guibas, Leonidas J. Hershberger, John Zhang, Li Zhu, An Department of Computer Science Stanford University Stanford CA 94305 United States Mentor Graphics 8005 S.W. Boeckman Road Wilsonville OR 97070 United States Compaq Systems Research Center 130 Lytton Avenue Palo Alto CA 94301 United States

ISBN: (纸本)1581134282

We propose a new routing graph, the Restricted Delaunay Graph (RDG), for ad hoc networks. Combined with a node clustering algorithm, RDG can be used as an underlying graph for geographic routing protocols. This graph has the following attractive properties: (1) it is a planar graph;(2) between any two nodes there exists a path in the RDG whose length, whether measure in terms of topological or Euclidean distance, is only a constant times the optimum length possible;and (3) the graph can be maintained efficiently in a distributed manner when the nodes move around. Furthermore, each node only needs constant time to make routing decisions. We also show by simulation that the RDG outperforms the previously proposed routing graphs under the Greedy Perimeter Stateless Routing (GPSR) protocol. In addition, we investigate theoretical bounds on the quality of paths discovered using GPSR.

关键词： Mobile telecommunication systems

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An OOP approach for mesh generation of multi-region models with NURBS

An OOP approach for mesh generation of multi-region models w...

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Brazilian Symposium on computer graphics and Image Processing (SIBGRAPI)

作者： W.M. Lira P.R. Cavalcanti L.C.G. Coelho L.F. Martha Department of Civil Engineering and Computer Graphics Technology Group Tecgraf Rio de Janeiro Rio de Janeiro Brazil Department of Computer Science Federal University of Rio de Janeiro Rio de Janeiro Rio de Janeiro Brazil

This paper presents an object-oriented approach for creating multi-region non-manifold models with NURBS. The main motivation is that the geometry and shape of realistic engineering objects are intrinsically complex, usually composed by several materials and regions. Therefore, automatic and/or adaptive meshing algorithms have become revealed themselves quite useful to increase the reliability of the procedures of a FEM numerical analysis. The present approach is concerned with two aspects of 3D FEM simulation: geometric modeling, with automatic multi-region detection, and support to automatic finite element mesh generation. The final objective is to use geometric models directly in numerical applications.

关键词： Mesh generation Object oriented modeling Solid modeling Spline Surface topography Surface reconstruction Geometry Shape Reliability engineering Numerical analysis

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Real-time out-of-core visualization of particle traces

Real-time out-of-core visualization of particle traces

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IEEE Symposium on Parallel and Large-Data Visualization and graphics (PVG)

作者： R. Bruckschen F. Kuester B. Hamann K.I. Joy Visualization and Graphics Research Group Center for Image Processing and Integrated Computing Department of Computer Science University of California Davis CA USA Visualization and Interactive Systems Group Department of Electrical and Computer Engineering University of California Irvine CA USA

ISBN: (纸本)0780372239

Visualization of particle traces provides intuitive and efficient means for the exploration and analysis of complex vector fields. The paper presents a method suitable for the real-time visualization of arbitrarily large time-varying vector fields in virtual environments. We describe an out-of-core scheme in which two distinct pre-processing and rendering components enable real-time data streaming and visualization. The presented approach yields low-latency application start-up times and small memory footprints. The described system was used to implement a "volumetric fog lance," which can emit up to 60000 particles into a flow field while maintaining an interactive frame rate of 60 frames per second. All algorithms were specifically designed to support commodity hardware. The proof-of-concept system is running on a low-cost Linux workstation equipped with a 120 GB E-IDE RAID (redundant array of inexpensive disk) system.

关键词： Data visualization Computational modeling Computational fluid dynamics Motion pictures Hardware computer graphics Interactive systems Image processing computer science Image analysis

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Simplified kinetic connectivity for rectangles and hypercubes 01

Simplified kinetic connectivity for rectangles and hypercube...

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Proceedings of the twelfth annual ACM-SIAM symposium on Discrete algorithms

作者： John Hershberger Subhash Suri Mentor Graphics Corp. 8005 SW Boeckman Road Wilsonville OR Computer Science Department Engineering I Room 2106 University of California Santa Barbara CA

ISBN: (纸本)9780898714906

We consider the problem of maintaining connected components in a set of moving objects using the kinetic data structure (KDS) framework. We assume that the motion of each object can be specified by a low-degree algebraic trajectory; this trajectory, however, can be modified in an on-line fashion. While the objects move continuously, their connectivity changes at discrete times. A straightforward dynamic graph approach for maintaining connectivity of n objects has three shortcomings: the graph can have Ω(n2) edges, the update bounds are amortized, and the algorithm is very complicated. Our first result shows that the connectivity for a set of n moving hypercubes can be maintained using a very simple, easy to determine graph with Ο(n) edges. But this graph still requires a general-purpose dynamic graph scheme for connectivity maintenance. Our main result is a simplified connectivity data structure for moving rectangles in the plane. For this special but important case, we are able to overcome all three shortcomings mentioned above: our graph has Ο(n) edges; our data structure supports updates in Ο(log2 n) worst-case time; and the algorithm and data structures are quite a bit simpler than those based on a general dynamic graph scheme.

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MIT educators share success

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computer graphics (ACM) 2001年第1期35卷 20-23页

作者： Wolfe, Rosalee Belcher, John W. Mark Bessette, R. Massachusetts Institute of Technology Astrophysics Division MIT Physics Department Studio/TEAL Project MIT New England 3D Studio Max Users Group Physics Demonstration Group MIT Department of Physics Center for Space Research Massachusetts Institute of Technology Center for Educational Computing Initiatives Massachusetts Institute of Technology Division of Graphics and Human-Computer Interaction School of Computer Science Telecommunications and Information Systems DePaul University School of Computer Science DePaul University Chicago IL 60604

Professor John Belcher developed a series of short videos with animation and text of selected experiments to properly demonstrate the phenomena of electromagnetism. Such 3D animations are visually compelling, instilling in the student both a sense of wonder about the phenomena and a mental model of why and how it works. The products of these approach includes video clips of demonstrations, 3D animations of these demonstration which display time changing field-lines as a guide to understanding their dynamical effects and Java applets which allow the student to actively construct and animate 2D field lines for varying configurations of sources. These technologies are also implemented to develop animations for Faraday's insights, using video clips.

关键词： computer graphics

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computer graphics in Germany

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computer graphics (ACM) 2001年第3期35卷 14-21页

作者： Saupe, Dietmar Alexa, Marc Chesnais, Alain Encarnação, Jose Institut für Informatik Universität Leipzig GRIS Technische Universität Darmstadt University of Leipzig Research Group on Computer Graphics and Image Processing Alias Wavefront 17 bis rue Joseph de Maistre 75018 Paris France Fraunhofer-Institut fuer Graphische Datenverarbeitung Wilhelminenstrasse 7 D-64283 Darmstadt Germany 3D Graphics Computing Department of Computer Science Technische Universität Darmstadt

The various institution and developments in the field of computer graphics in Germany is discussed. The German Research Foundation( DFG), as recognition of research in computer graphics, sponsors a special interdisciplinary graduates study program on 3D image analysis and synthesis at the University of Erlangen-Nuremburg. The German Association for Informatics, founded in 1983, brings together about 40 representatives from Universities, colleges and industry that co-ordinate activities form five subgroups specializing in foundations and systems, imaging and visualization, graphical user interfaces, simulation and animation, and geometric modeling. Several companies and forums working in the area of computer graphics are situated in Darmstadt.

关键词： computer graphics

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computer graphics in China: An overview

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computer graphics (ACM) 2001年第2期35卷 22-27页

作者： Shi, Jiaoying Pan, Zhigeng Chesnais, Alain Encarnação, Jose Zhejiang University Alias Wavefront 17 bis rue Joseph de Maistre 75018 Paris France Fraunhofer-Institut fuer Graphisdie Dateverabeiung Wilhelminenstraas 7 D-64283 Darmstadt Germany Department of Computer Science and Engineering Zhejiang University China SIGGRAPH Education Committee State Key Lab. CAD and CG Zhejiang University Hangzhou 310027 China State Key Lab. CAD and CG Zhejiang University SIGGRAPH China Image and Graphics Association

An overview of the research and development of computer graphics in China, especially in the area of virtual reality, is discussed. computer graphics performs an important role in both academia and industry and enables a broad variety of applications like CAD, CAM, geographical information systems (GIS), publishing, games and film making industries. Universities and Institutes are the main units engaged in the research and development of computer graphic techniques. computer graphic research includes visualization, geometric modeling, computer-aided geometric design, and realistic rendering. It is expected that researchers in China will continue to make promising achievements and contributions in the field of computer graphics.

关键词： computer graphics

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Compressed progressive meshes (vol 6, pg 79, 2000)

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IEEE TRANSACTIONS ON VISUALIZATION AND computer graphics 2000年第2期6卷 190-192页

作者： Pajarola, R Rossignac, J Information and Computer Science Department University of California Irvine Graphics Visualization and Usablity Center Georgia Institute of Technology

Most systems that support visual interaction with 3D models use shape representations based on triangle meshes. The size of these representations imposes limits on applications for which complex 3D models must be accessed remotely. Techniques for simplifying and compressing 3D models reduce the transmission time. Multiresolution formats provide quick access to a crude model and then refine it progressively. Unfortunately, compared to the best nonprogressive compression methods, previously proposed progressive refinement techniques impose a significant overhead when the full resolution model must be downloaded. The CPM (Compressed Progressive Meshes) approach proposed here eliminates this overhead. It uses a new technique, which refines the topology of the mesh in batches, which each increase the number of vertices by up to 50 percent. Less than an amortized total of 4 bits per triangle encode where and how the topological refinements should be applied. We estimate the position of new vertices from the positions of their topological neighbors in the less refined mesh using a new estimator that leads to representations of vertex coordinates that are 50 percent more compact than previously reported progressive geometry compression techniques.

关键词： Triangle mesh compression Progressive Meshes Multiresolution Modeling Geometry Compression

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Preface

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Lecture Notes in computer science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) 2001年 2037卷 V-VI页

作者： Boers, Egbert J. W. Cagnoni, Stefano Gottlieb, Jens Hart, Emma Lanzi, Pier Luca Raidl, Günther R. Smith, Robert E. Tijink, Harald Leiden Institute of Advanced Computer Science Leiden University Niels Bohrweg 1 Leiden Netherlands Dept. of Computer Engineering University of Parma Parco Area delle Scienze 181/a Parma Italy SAP AG Neurottstrasse 16 Walldorf Germany Napier University School of Computing 219 Colinton Road Edinburgh United Kingdom Polytechnic of Milan Piazza Leonardo da Vinci 32 Milan Italy Algorithms and Data Structur es Group Institute of Computer Graphics Vienna University of Technology Favoritenstrasse 9-11/186 Vienna Austria The Intelligent Computer Systems Centre The University of The West of England Coldharbour Lane Frenchay Bristol United Kingdom Data and Knowledge Systems Department National Aerospace Laboratory NLR P.O. Box 153 Emmeloord Netherlands

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A steganographic framework for reference colour based encoding and cover image selection 3

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3rd International Workshop on Information Security, ISW 2000

作者： Rosenbaum, René Schumann, Heidrun University of Rostock Department of Computer Science Institute for Computer Graphics RostockD-18059 Germany

ISBN: (纸本)3540414169

Steganography is a method of communication which hides the existence of the communication from a third *** employment of steganographic techniques depends on various demands, which will be derived and considered. This paper regards different aspects of digital images. These are representation, storage and as a result also suitability for their use in steganography. Based upon this, some criteria for the choice of suitable cover images are pointed out. A new technical steganographic system, which uses reference colours as starting point for embedding and extraction of information has been developed and will be described. This system can be adapted flexibly to different requirements and considers the human visual system as well as the derived statements for potential cover images. Results are described which justify the new approach. © Springer-Verlag Berlin Heidelberg 2000.

关键词： Steganography

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