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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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A word extraction algorithm for machine-printed documents using a 3D neighborhood graph model

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International Journal on Document Analysis and Recognition 2001年第2期4卷 115-130页

作者： Park, Hwan-Chul Ok, Se-Young Yu, Young-Jung Cho, Hwan-Gue R and D Center PAXVR Seocho Jeil B/D 1624-2 Seocho-Dong Seocho-Ku Seoul 137-878 Korea Republic of LG Innotek Yongin-shi Kyunggi-do Korea Republic of Graphics Application Lab. Department of Computer Science Pusan National University Kum-Jung-Ku Pusan 609-735 Korea Republic of

Automatic character recognition and image understanding of a given paper document are the main objectives of the computer vision field. For these problems, a basic step is to isolate characters and group words from these isolated characters. In this paper, we propose a new method for extracting characters from a mixed text/graphic machine-printed document and an algorithm for distinguishing words from the isolated characters. For extracting characters, we exploit several features (size, elongation, and density) of characters and propose a characteristic value for classification using the run-length frequency of the image component. In the context of word grouping, previous works have largely been concerned with words which are placed on a horizontal or vertical line. Our word grouping algorithm can group words which are on inclined lines, intersecting lines, and even curved lines. To do this, we introduce the 3D neighborhood graph model which is very useful and efficient for character classification and word grouping. In the 3D neighborhood graph model, each connected component of a text image segment is mapped onto 3D space according to the area of the bounding box and positional information from the document. We conducted tests with more than 20 English documents and more than ten oriental documents scanned from books, brochures, and magazines. Experimental results show that more than 95% of words are successfully extracted from general documents, even in very complicated oriental documents. © 2001 Springer-Verlag Berlin Heidelberg.

关键词： Character recognition

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Explicit control of topological transitions in morphing shapes of 3D meshes

Explicit control of topological transitions in morphing shap...

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Pacific Conference on computer graphics and Applications

作者： S. Takahashi Y. Kokojima R. Ohbuchi Department of Graphics and Computer Science Graduate School of Arts and Sciences University of Tokyo Japan Corporate Research and Development Center Toshiba Corporation Japan Computer Science Department Faculty of Engineering Yamanashi University Japan

Existing methods of morphing 3D meshes are often limited to cases in which 3D input meshes to be morphed are topologically equivalent. The paper presents a new method for morphing 3D meshes having different surface topological types. The most significant feature of the method is that it allows explicit control of topological transitions that occur during the morph. Transitions of topological types are specified by means of a compact formalism that resulted from a rigorous examination of singularities of 4D hypersurfaces and embeddings of meshes in 3D space. Using the formalism, every plausible path of topological transitions can be classified into a small set of cases. In order to guide a topological transition during the morph, our method employs a key frame that binds two distinct surface topological types. The key frame consists of a pair of "faces", each of which is homeomorphic to one of the source (input) 3D meshes. Interpolating the source meshes and the key frame by using a tetrahedral 4D mesh and then intersecting the interpolating mesh with another 4D hypersurface creates a morphed 3D mesh. We demonstrate the power of our methodology by using several examples of topology transcending morphing.

关键词： Shape control computer science Topology Visual effects Research and development computer graphics Art Motion pictures TV Medical services

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Geometric spanner for routing in mobile networks 01

Geometric spanner for routing in mobile networks

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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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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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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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Computing the penetration depth of two convex polytopes in 3d 7th

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7th Scandinavian Workshop on Algorithm Theory, SWAT 2000

作者： Agarwal, Pankaj K. Guibas, Leonidas J. Har-Peled, Sariel Rabinovitch, Alexander Sharir, Micha Center for Geometric Computing Department of Computer Science Duke University Box 90129 DurhamNC27708-0129 United States Computer Graphics Laboratory Computer Science Department Stanford University StanfordCA94305 United States Synopsys Inc 154 Crane Meadow Rd Suite 300 MarlboroMA01752 United States School of Mathematical Sciences Tel Aviv University Tel Aviv69978 Israel Courant Institute of Mathematical Sciences New York University NY10012 United States

ISBN: (纸本)3540676902

Let A and B be two convex polytopes in R3 with m and n facets, respectively. The penetration depth of A and B, denoted as π(A, B), is the minimum distance by which A has to be translated so that A and B do not intersect. We present a randomized algorithm that computes π(A,B) in O(m3/4+ɛn3/4+ɛ + m1+ɛ + n1+ɛ) expected time, for any constant ɛ > 0. It also computes a vector t such that ||t|| = π(A,B) and int(A + t) ⊓ B = θ. We show that if the Minkowski sum B ⊗ (—A) has K facets, then the expected running time of our algorithm is O (K1/2+ɛm1/4n1/4 + m1+ɛ + n1+ɛ), for any ɛ > 0. We also present an approximation algorithm for computing π(A,B). For any δ > 0, we can compute, in time O(m + n + (log2(m + n))/δ), a vector t such that ||t|| 2 n)/δ), which is simpler and slightly faster than the recent algorithm by Chan. © Springer-Verlag Berlin Heidelberg 2000.

关键词： Approximation algorithms

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A spreadsheet interface for visualization exploration 00

A spreadsheet interface for visualization exploration

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Proceedings of the conference on Visualization '00

作者： T. J. Jankun-Kelly Kwan-Liu Ma Computer Science Department Visualization and Graphics Research Group. Center for Image Processing and Integrated Computing University of California Davis CA

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Fast and stable animation of cloth with an approximated implicit method

Fast and stable animation of cloth with an approximated impl...

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computer graphics International

作者： Young-Min Kang Jeong-Hyeon Choi Hwan-Gue Cho Chan-Jong Park Graphics Application Lab Department of Computer Science Pusan National University South Korea Virtual Reality Center Electronics and Telecommunication Research Institute

Realistic animation of soft objects such as cloth is essential for plausible character animation. Many techniques have been proposed for the simulation of soft objects, and most of them are based on numerical integration. Among the techniques, the implicit integration method is the most likely technique for real time environments, since it allows large time steps for cloth simulation by ensuring the stability of systems. However the most critical flaw of the implicit method is that it involves a large linear system. The paper presents a fast animation technique for animating soft objects based on a mass-spring model with an approximated implicit method which does not involve linear system solving. The proposed technique stably updates the state of n mass-points in O(n) time when the number of total springs are O(n). Because the mass-spring model shows a superelastic effect, the excessively deformed springs (i.e., super-elongated springs) should be adjusted for reality. The paper presents an efficient inverse dynamics process to adjust the super-elongated springs.

关键词： Animation Springs Computational modeling Linear systems Stability Deformable models Electrical capacitance tomography Image generation computer graphics Application software

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On switch factor based analysis of coupled RC interconnects

On switch factor based analysis of coupled RC interconnects

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Design Automation Conference

作者： A.B. Kahng S. Muddu E. Sarto Silicon Graphics Inc. Mountain View CA USA UCLA Computer Science Department Los Angeles CA USA 3dfx Interactive Inc. San Jose CA USA

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