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Proceedings - 2nd International Symposium on 3D Data Processing, Visualization, and Transmission. 3DPVT 2004

作者： Bogomjakov, Alexander Gotsman, Craig Ctr. Graphics and Geometric Comp. Computer Science Dept. Technion - Israel Inst. of Technol. Haifa 32000 Israel

ISBN: (纸本)0769522238

Height fields and depth maps which we collectively refer to as z-fields, usually carry a lot of redundant information and are often used in real-time applications. This is the reason why efficient methods for their simplification are necessary. On the other hand, the comp.tation power and programmability of commodity graphics hardware has significantly grown. We present an adaptation of an existing real-time z-field simplification method for execution in graphics hardware. The main parts of the algorithm are implemented as fragment programs which run on the GPU. The resulting polygonal models are identical to the ones obtained by the original method. The main benefit is that the comp.tation load is imposed on the GPU, freeing-up the CPU for other tasks. Additionally, the new method exhibits a performance improvement when comp.red to a pure CPU implementation. © 2004 IEEE.

关键词： Maps

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The VesselGlyph: Focus & context visualization in CT-angiography

The VesselGlyph: Focus & context visualization in CT-angiogr...

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IEEE Visualization 2004 - Proceedings, VIS 2004

作者： Straka, Matúš Köchl, Arnold Červeňanský, Michal Šrámek, Miloš Fleischmann, Dominik La Cruz, Alexandra Gröller, Eduard Commn. for Scientific Visualization Austrian Academy of Sciences Medical University of Vienna Austria Comenius University Bratislava Slovakia Stanford University Medical Center United States Inst. Comp. Graphics and Algorithms Vienna University of Technology Austria

ISBN: (纸本)0780387880

Accurate and reliable visualization of blood vessels is still a challenging problem, notably in the presence of morphologic changes resulting from atherosclerotic diseases. In this paper we take advantage of partially segmented data with approximately identified vessel centerlines to comp.ehensively visualize the diseased peripheral arterial tree. We introduce the VesselGlyph as an abstract notation for novel focus & context visualization techniques of tubular structures such as contrast-medium enhanced arteries in CT-Angiography (CTA). The proposed techniques combine direct volume rendering (DVR) and curved planar reformation (CPR) within a single image. The VesselGlyph consists of several regions where different rendering methods are used. The region type, the used visualization method and the region parameters depend on the distance from the vessel centerline and on viewing parameters as well. By selecting proper rendering techniques for different regions, vessels are depicted in a naturally looking and undistorted anatomic context. This may facilitate the diagnosis and treatment planning of patients with peripheral arterial occlusive disease. In this paper we furthermore present a way how to implement the proposed techniques in software and by means of modem 3D graphics accelerators. ©2004 IEEE.

关键词： Angiography

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Modeling and Visualizing the Cultural Heritage Data Set of Graz

Modeling and Visualizing the Cultural Heritage Data Set of G...

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Proceedings VAST 2001 Virtual Reality, Archeology, and Cultural Heritage

作者： Zach, Christopher Klaus, Andreas Bauer, Joachim Karner, Konrad Grabner, Markus VRVis Res. Ctr. Virtual Reality/V. Inst. for Comp. Graphics and Vision Inffeldgasse 16 Graz Austria

ISBN: (纸本)1581134479

The inner city (Old Town) of Graz will be the European cultural capital in 2003. In this paper we present preliminary results on the reconstruction and visualization of this kind of cultural heritage data. Starting with a simple block model obtained by converting 2 1/2 dimensional GIS (geographic information system) data we focus on the image based modeling of the facades. Herein we illustrate a robust search for corresponding points to estimate the relative orientation between image pairs. Additional, we outline our real-time rendering approach based on a LOD-R-tree concept. Special attention is paid on the LOD (level of detail) generation for historic buildings where two different ways working in 2D and 3D are explained. The visualization system is communicating asynchronously with a database system storing the LOD-R-tree data structure. This client-server configuration provides interactive navigation through the virtual scene and the scalability of a database management system.

关键词： Virtual reality

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The comp.exity of Jensen's algorithm for counting polyominoes

The complexity of Jensen's algorithm for counting polyominoe...

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Proceedings of the Sixth Workshop on Algorithm Engineering and Experiments and the First Workshop on Analytic algorithms and Combinatorics

作者： Barequet, Gill Moffie, Micha Ctr. Graphics and Geometric Comp. Dept. of Computer Science Technion - Israel Inst. of Technol. Haifa 32000 Israel

ISBN: (纸本)0898715644

Recently I. Jensen published a novel transfer-matrix algorithm for comp.ting the number of polyominoes in a rectangular lattice. However, his estimation of the comp.tational comp.exity of the algorithm (O((√2) n)) where n is the size of the polyominoes), was based only on empirical evidence. This paper is based primarily on an analysis of the number of some class of strings that plays a significant role in the algorithm. It turns out that this number is closely related to Motzkin's numbers. We provide a rigorous comp.tation that roughly confirms Jensen's estimation. We obtain the bound O(n5/2(√3)n) on the running time of the algorithm, while the actual number of polyominoes is about C4.06n/n, for some constant C > 0.

关键词： comp.tational comp.exity

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Generation of VRML city models for focus based tour animations

Generation of VRML city models for focus based tour animatio...

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Proceedings Web3D 2002 Symposium: 7th International Conference on 3D Web Technology

作者： Schilling, Arne Zipf, Alexander Fraunhofer Inst. for Comp. Graphics Fraunhoferstr. 5 64283 Darmstadt Germany European Media Laboratory EML Schloß-Wolfsbrunnenweg 33 69118 Heidelberg Germany

In order to generate 3D worlds in an automated way it is important to solve the problem of integrating existing 2D and 3D data automatically. We explain some of the issues of this problem in this paper. We also introduce mechanisms for automated generation of integrated 3D geo-data sets, as well as a prototype that implements these. It is necessary to distinguish the different problems and methods for the generation of buildings and other man made structures on the one hand and digital elevation models and land use areas on the other. Using the integrated data and the developed algorithms we work on a strategy for the dynamic generation of 3D tour animations through a virtual city and landscape model that is optimized for a specific tour. We introduce comp.nents that allow the generation of a virtual 3D-tour through our demonstration region - the city of Heidelberg - by the automated integration of 2D and 3D data sources to a 3D model. The user is presented with an interactive animation of a 3D scene of a dynamically calculated tour through the hybrid 3D model of Heidelberg focusing on the area around the tour.

关键词： Virtual reality

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Video watermarking based on time-axis template

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Tien Tzu Hsueh Pao/Acta Electronica Sinica 2004年第8期32卷 1236-1238页

作者： Niu, Xia-Mu Schmucker, Martin Busch, Christoph Harbin Inst. of Technol. P.O. Box 339 Harbin 150001 China Framhofer Inst. for Comp. Graphics Fraunhoferstr 5 D-64283 Darmstadt Germany

A video watermarking which resists affine transformations is proposed. A template along the time axis is inserted in each Watermark Minimum Segment (WMS) of the video sequence. Experimental results show that the water... 详细信息

关键词： Digital watermarking

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Multi-layered architecture for sketch-based interaction within virtual environments

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comp.ters and graphics (Pergamon) 2000年第6期24卷 851-867页

作者： Bimber, Oliver Encarnação, L. Miguel Stork, André Fraunhofer Inst. for Comp. Graphics Joachim-Jungius-Strasse 11 18059 Rostock Germany Fraunhofer Ctr. Res. Comp. G. 321 S. Main St. Providence RI 02903 United States Fraunhofer Inst. for Comp. Graphics Rundeturmstrasse 6 64283 Darmstadt Germany

In this article, we describe a multi-layered architecture for sketch-based interaction within virtual environments. Our architecture consists of eight hierarchically arranged layers that are described by giving examples of how they are implemented and how they interact. Focusing on table-like projection systems (such as Virtual Tables or Responsive Workbenches) as human-centered output-devices, we show examples of how to integrate parts or all of the architecture into existing domain-specific applications - rather than realizing new general sketch applications - to make sketching an integral part of the next-generation human-comp.ter interface.

关键词： Virtual reality

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Investigating human-comp.ter optimization 02

Investigating human-computer optimization

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Conference on Human Factors in comp.ting Systems

作者： Scott, Stacey D. Lesh, Neal Klau, Gunnar W. Mitsubishi Elec. Res. Laboratories 201 Broadway Street Cambridge MA 02139 United States School of Computing Science Simon Fraser University Burnaby BC V5A 1S6 Canada Inst. of Comp. Graphics/Algorithms Vienna University of Technology Favoritenstr. 9-11 A-1040 Vienna Austria

ISBN: (纸本)9781581134537

Scheduling, routing, and layout tasks are examples of hard optimization problems with broad application in industry. Past research in this area has focused on algorithmic issues. However, this approach neglects many important human-comp.ter interaction issues that must be addressed to provide people with practical solutions to optimization problems. Automatic methods do not leverage human expertise and can only find solutions that are optimal with regard to an invariably over-simplified problem description. Furthermore, users must understand the generated solutions in order to implement, justify, or modify them. Interactive optimization helps address these issues but has not previously been studied in detail. This paper describes experiments on an interactive optimization system that explore the most appropriate way to combine the respective strengths of people and comp.ters. Our results show that users can successfully identify promising areas of the search space as well as manage the amount of comp.tational effort expended on different subproblems.

关键词： Human comp.ter interaction

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Semantically controlled LMV techniques for plant design review

Semantically controlled LMV techniques for plant design revi...

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2004 ASME Design Engineering Technical Conferences and comp.ters and Information in Engineering Conference

作者： Posada, Jorge Wundrak, Stefan Stork, Andre Toro, Carlos VICOMTech Research Center Parque Tecn. Miramón Paseo Mikeletegi 57 20009 Donostia-San Sebastián Spain Fraunhofer Inst. for Comp. Graphics Fraunhoferstr. 5 D-64283 Darmstadt Germany

Inspecting large industrial plants in a virtual walkthrough environment has proven to be a valuable tool in Plant Design. Many CG techniques, such as various LOD and culling methods, have been developed to visualize comp.ex models in VR environments. These techniques decide solely based on geometric properties how to optimize the scene. In this paper we introduce the concept of semantically controlled selection of those techniques and show how semantic considerations can enhance the CAD to VR conversion process for large model visualization (LMV) walkthroughs of Plant Design models, improving the performance and adapting the visualization to the users' needs. A taxonomy, together with semantic considerations coming from the relationship between user, model, and resources is the basis to decide which rules should be applied for a specific visualization technique. By extending a LMV walkthrough system we are able to reduce the comp.exity of large industrial plant models by a factor of two. On a common workplace PC the semantic preprocessing takes only 10-20 minutes for models with 106 to 10 polygons. Our approach is orthogonal to commonly known CG techniques and can be combined beneficially with those approaches.

关键词： comp.ter aided design

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Presenting route inst.uctions on mobile devices 03

Presenting route instructions on mobile devices

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2003 International Conference on Intelligent User Interfaces

作者： Kray, Christian Laakso, Katri Elting, Christian Coors, Volker Stuhlsatzenhausweg 3 66123 Saarbrücken Germany Itämerenkatu 11-13 00180 Helsinki Finland Schloss-Wolfsbrunnenweg 33 69118 Heidelberg Germany Fraunhofer Inst. Comp. Graphics Fraunhoferstr. 5 64295 Darmstadt Germany

ISBN: (纸本)9781581135862

In this paper, we evaluate several means of presenting route inst.uctions to a mobile user. Starting from an abstract language- independent description of a route segment, we show how to generate various presentations for a mobile device ranging from spoken inst.uctions to 3D visualizations. We then examine the relationship between the quality of positional information, available resources and the different types of presentations. The paper concludes with guidelines that help to determine which presentation to choose for a given situation.

关键词： Mobile telecommunication systems

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