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Intelligent Cruise-Control Navigation: A New Navigation/ Travel Method for Use in Virtual Environments

Virtual Reality 2000年第1期5卷 23-31页

作者： Kwon, Tae-Wook Choy, Yoon-Chul Multimedia/Graphics Lab. Dept. of Computer Science Yonseï University Seoul South Korea Multimedia/Graphics Lab. Department of Computer Science Yonsei University Seoul 720-749 South Korea

An important feature of virtual reality is the facility for the user to move around a virtual environment in a natural and easily controlled manner. Navigation, also called locomotion, travel or motion, involves changing the perspective of the user in the virtual environment (VE). It allows the user to move in the VE as well as reorient themselves to look at the world differently. Natural locomotion methods are able to contribute to a sense of presence and reality. The illusion of presence can be lost through unnatural experiences during travel in the VE. This can be caused by poor interactive metaphors or by experiences which do not agree with the user's everyday understanding of the real world. This paper focuses on the navigation method in the VE, one of the major interfaces for the interactivity between human and VE in virtual reality circumstances and worlds. It proposes a new navigation method, Intelligent Cruise-Control Navigation (ICCN). which provides a natural and user-centred approach to navigation in the VE and can improve the user's sense of reality and presence. ICCN is composed of three major phases: Constant Velocity Navigation, Collision Detection and Avoidance, and Path Adjustment. The ICCN can reduce the user's fatigue and improve the user's presence in the VE. The small experimental study reported in this paper suggests that the ICCN will be a natural, straightforward, and useful navigation interface in VE. © Springer-Verlag London Ltd.

关键词： Collision detection and avoidance Constant velocity navigation Hands-free navigation Intelligent cruisecontrol navigation Locomotion Navigation: Path adjustment Travel

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Multimodal integration using complex feature set

Multimodal integration using complex feature set

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3rd International Conference on Multimodal Interfaces, ICMI 2000

作者： Bin, Xiao Jiantao, Pu Shihai, Dong Graphics Laboratory Department of Computer Science and Technology Peking University Beijing100871 China

ISBN: (纸本)3540411801

Multimodal integration is an important problem of multimodal user interface research. After briefly surveying research on multimodal integration, this paper introduced a natural language processing method to resolve the problem of integration. It introduced the unification operation on complex feature set and extended this operation in order to represent the information from input modalities and implement multimodal integration. © Springer-Verlag Berlin Heidelberg 2000.

关键词： Integration

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Constrained C1 piecewise bicubic Bézier surface interpolation

Constrained C1 piecewise bicubic Bézier surface interpolati...

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Geometric Modeling and Processing 2000, GMP 2000

作者： Zhang, Caiming Cheng, Fuhua Barsky, B.A. Graphics and Geometric Modeling Lab. Department of Computer Science University of Kentucky LexingtonKY40506 United States Department of Computer Science University of California BerkeleyCA94720 United States

ISBN: (纸本)0769505627

The construction of a C1 piecewise bicubic Bézier surface that interpolates a set of data points and lies on the same side of a given plane as the data points is presented. The main tasks in this construction process are the adjustment of the tangent vectors and the determination of the twist vectors at the data points. The tangent vectors are modified by decreasing their magnitudes. The twist vectors are first set by an energy minimization process and then filtered through a modification process to ensure the constructed surface lies on one side of the given plane. The technique for determining the twist vectors has an interpolation precision of cubic polynomials. © 2000 IEEE.

关键词： Interpolation

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Constrained shape scaling of multi-surface objects

Constrained shape scaling of multi-surface objects

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Geometric Modeling and Processing 2000, GMP 2000

作者： Zhang, Pifu Zhang, Caiming Cheng, Fuhua Graphics and Geometric Modeling Lab. Department of Computer Science University of Kentucky LexingtonKY40506-0046 United States

ISBN: (纸本)0769505627

A method to scale a multi-surface object while holding the shape and size of specific features (trimming curves) unchanged is presented. The new method includes an earlier version for a one-NURBS-surface object as a special case by considering more general objects and more general features. The constrained scaling process is attach-and-deform based. The new surface is constructed by attaching the original features to a scaled version of the given object. The attaching process requires several transformations and a deformation of the scaled object. The resulting object has the same features as the original object while reflecting the shape and curvature distribution of the scaled object. The presented approach maintains a NURBS representation for each component surface of the resulting object and hence, is compatible with most of the current data-exchange standards. Test results on several car body surfaces with trimming curves are included. The quality of the resulting surfaces is examined using the highlight line model. © 2000 IEEE.

关键词： Strain energy

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Request sequencing: Optimizing communication for the grid 6

引用

6th International European Conference on Parallel Computing, Euro-Par 2000

作者： Arnold, Dorian C. Bachmann, Dieter Dongarra, Jack Department of Computer Science University of Tennessee KnoxvilleTN37996 United States Computer Graphics and Vision Graz University of Technology Inffeldg. 16/E/2 GrazA-8010 Austria

ISBN: (纸本)9783540679561

As we research to make the use of Computational Grids seamless, the allocation of resources in these dynamic environments is proving to be very unwieldy. In this paper, we introduce, describe and evaluate a technique we call request sequencing. Request sequencing groups together requests for Grid services to exploit some common characteristics of these requests and minimize network traffic. The purpose of this work is to develop and validate this approach. We show how request sequencing can affect scheduling policies and enable more expedient resource allocation methods. We also discuss some of the reasons for our design, offer the initial results and discuss issues that remain outstanding for future research. © Springer-Verlag Berlin Heidelberg 2000.

关键词： Resource allocation

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Construct3D: A virtual reality application for mathematics and geometry education

引用

Education and Information Technologies 2000年第4期5卷 263-276页

作者： Kaufmann, Hannes Schmalstieg, Dieter Wagner, Michael Institute of Geometry Vienna University of Technology Austria 3370 Ybbs/Donau Lange Gasse 3 Austria Institute of Computer Graphics Vienna University of Technology Austria Department of Computer Science and Engineering Arizona State University United States

Construct3D is a three dimensional geometric construction tool based on the collaborative augmented reality system 'Studierstube'. Our setup uses a stereoscopic head mounted display (HMD) and the Personal Interaction Panel (PIP) - a two-handed 3D interaction tool that simplifies 3D model interaction. Means of application in mathematics and geometry education at high school as well as university level are being discussed. A pilot study summarizes the strengths and possible extensions of our system. Anecdotal evidence supports our claim that the use of Construct3D is easy to learn and encourages experimentation with geometric constructions. © 2000 Kluwer Academic Publishers.

关键词： 3D modelling Enhancing spatial abilities Geometry education User-interface design Virtual reality

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Locality in decoder-based EAs for the multidimensional knapsack problem 4

引用

4th European Conference on Artificial Evolution, AE 1999

作者： Gottlieb, Jens Raidl, Günther R. Department of Computer Science Technical University of Clausthal Julius-Albert-Str. 4 Clausthal-Zellerfeld38678 Germany Institute for Computer Graphics Vienna University of Technology Karlsplatz 13/1861 Vienna1040 Austria

ISBN: (纸本)9783540678465

The performance of decoder-based evolutionary algorithms (EAs) strongly depends on the locality of the used decoder and opera- tors. While many approaches to characterize locality are based on the fitness landscape, we emphasize the explicit relation between genoty- pes and phenotypes. Statistical measures are demonstrated to reliably predict locality properties of selected decoder-based EAs for the multi- dimensional knapsack problem. Empirical results indicate that (i) strong locality is a necessary condition for high performance, (ii) the concept of heuristic bias also strongly affects solution quality, and (iii) it is im- portant to maintain population diversity, e.g. by phenotypic duplicate elimination. © Springer-Verlag Berlin Heidelberg 2000.

关键词： Combinatorial optimization

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A new virtual planning system for neuroendoscopic interventions

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Klinische Neuroradiologie 2000年第4期10卷 153-160页

作者： Freudenstein, Dirk Bartz, Dirk Merkle, Martin Ernemann, Ulrike Skalej, Martin Duffner, Frank Department of Neurosurgery University Hospital Eberhard-Karls University Tübingen Germany Wilhelm Schickard Institute for Computer Science Computer Graphics Lab Eberhard-Karls University Tübingen Germany Department of Neuroradiology University Hospital Eberhard-Karls University Tübingen Germany

The demand on virtual planning systems is increasing, in particular for technical pretentious surgical interventions such as intracranial endoscopy. In this paper, a new virtual system for neuroendoscopy is presented. The main purpose of this system is to provide support for the planning and training of neuroendoscopic interventions. The software is applied for virtual endoscopic visualization of three-dimensional magnetic resonance data sets, using a clinical magnetic resonance scanner. Rendering is performed on a Hewlett-Packard unix workstation. Virtual endoscopy provides a three-dimensional view of the cerebral ventricles with good visualization of anatomic details. The rendering system used allows the generation of fly-through sequences through the entire ventricular system in real-time. Navigation is controlled by mouse movements. The visualization of the computer generated intraventricular spaces is adapted to the characteristics of the optical endoscope. The presented virtual neuroendoscopy system is a promising tool for planning and training of neuroendoscopic procedures. It provides the ability to simulate these procedures based on the patient's individual anatomy, prior to surgery.

关键词： Neuroendoscopy Neuronavigation Neurosurgery Virtual endoscopy Virtual environments Virtual medicine

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A weighted coding in a genetic algorithm for the degree-constrained minimum spanning tree problem 00

A weighted coding in a genetic algorithm for the degree-cons...

引用

2000 ACM Symposium on Applied Computing, SAC 2000

作者： Raidl, Günther R. Julstrom, Bryant A. Institute of Computer Graphics Vienna University of Technology Karlsplatz 13/1861 1040 Vienna Austria Department of Computer Science St. Cloud State University St. Cloud MN 56301 United States

ISBN: (纸本)1581132409

The coding by which chromosomes represent candidate solutions is a fundamental design choice in a genetic algorithm. This paper describes a novel coding of spanning trees in a genetic algorithm for the degree-constrained minimum spanning tree problem. For a connected, weighted graph, this problem seeks to identify the shortest spanning tree whose degree does not exceed an upper bound k ≥ 2. In the coding, chromosomes are strings of numerical weights associated with the target graph's vertices. The weights temporarily bias the graph's edge costs, and an extension of Prim's algorithm, applied to the biased costs, identifies the feasible spanning tree a chromosome represents. This decoding algorithm enforces the degree constraint, so that all chromosomes represent valid solutions and there is no need to discard, repair, or penalize invalid chromosomes. On a set of hard graphs whose unconstrained minimum spanning trees are of high degree, a genetic algorithm that uses this coding identifies degree-constrained minimum spanning trees that are on average shorter than those found by several competing algorithms. © 2000 ACM.

关键词： Chromosomes

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A wireless, inexpensive optical tracker for the CAVE/sup TM/

A wireless, inexpensive optical tracker for the CAVE/sup TM/

引用

IEEE Annual International Symposium Virtual Reality

作者： E. Sharlin P. Figueroa M. Green B. Watson Computer Graphics Laboratory Department of Computing Science University of Alberta Canada

CAVE/sup TM/ displays offer many advantages over other virtual reality (VR) displays, including a large, unencumbered viewing space. Unfortunately, the typical tracking subsystems used with CAVE/sup TM/ displays tether the user and lessen this advantage. We have designed a simple, low-cost foot tracker that is wireless, leaving the user free to move. The tracker can be assembled for less than $200 US, and achieves an accuracy of /spl plusmn/10 cm at a 20-Hz sampling rate. We have tested the prototype with two applications: a visualization supporting close visual inspection, and a walkthrough of the campus. Although the tracking was convincing, it was clear that the tracker's limitations make it less than ideal for applications requiring precise visual inspection. However the freedom of motion allowed by the tracker was a compelling supplement to our campus walkthrough, allowing users to stroll and look around corners.

关键词： Displays Virtual reality Inspection Foot Assembly Sampling methods Testing Prototypes Visualization Tracking

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