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International Conference on computer science and Software Engineering, CSSE 2008

作者： Baker, Ashraf Abu Milanovic, Borislav Institute for Computer Graphics Department of Computer Science and Mathematics J. W. Goethe University Frankfurt Germany

ISBN: (纸本)9780769533360

The increasing demands on interactive algorithm visualisations that can be effectively used in learning, teaching and research, as well as the lack of up-to-date visualisation systems calls for a new modern architecture for universal algorithm visualisation systems (AVS). Defining a new architecture requires an extensive analysis of existing AVS and specifying key requirements, which the architecture has to meet. Analysing current AVS and comparing them to each other, we came to the decision that there is a great potential for designing and implementing a new universal and extensible modern architecture. Based on our analysis and motivated by the decreasing interest on algorithm improvisations by both developers and faculty over the last few years, we have developed and implemented a generic architecture that we will briefly present in this work. The application of this architecture simplifies the creation process of pedagogically effective visualisations of arbitrary algorithms and data structures. © 2008 IEEE.

关键词： Visualization

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Multi-user video streaming over multiple heterogeneous wireless networks: A distributed, cross-layer design paradigm

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Journal of Internet Technology 2009年第1期10卷 1-11页

作者： Zhou, Liang Geller, Benoît Wang, Xiaojun Wei, Anne Zheng, Baoyu Chao, Han-Chieh Shanghai Jiao Tong University Shanghai China Ecole Normale Supperieure Cachan France E.N.S.T.A.-Paris Tech Paris France School of Electronic Engineering of Dublin City University Ireland University of Toulouse II France Nanjing University of Posts and Telecommunications Nanjing China Department of Electronic Engineering Institute of Computer Science and Information Engineering National Ilan University China

In this paper, we address the problem of QoS (Quality of Service) provisioning for multi-user video streaming over multiple heterogeneous wireless networks based on the distributed, cross-layer design framework. By jointly considering the rate allocation and the Joint Source-Channel Coding (JSCC), our proposal aims at maximizing the QoS provisioning under the given resource constraint. At first, we develop and evaluate a framework for optimal video rate allocation over multiple networks based on the observed Available Bit Rate (ABR) and the Round Trip Time (RTT) over each access network, as well as the video rate-distortion characteristics. The rate allocation is formulated as a convex optimization problem that minimizes the sum of all video streams expected distortion. Then, we propose an analytical JSCC scheme for error-resilient scalable encoded video, and integrate the JSCC with the specific rate allocation algorithm to improve the constructed video quality by optimally applying the appropriate channel coding rate given the constraints imposed by the transmission rate and the prevailing channel conditions. Objective and subjective simulation results are provided which demonstrate the effectiveness of our proposed joint scheme.

关键词： Video streaming

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Automatic differentiation for GPU-accelerated 2D/3D registration

Automatic differentiation for GPU-accelerated 2D/3D registra...

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5th International Conference on Automatic Differentiation

作者： Grabner, Markus Pock, Thomas Gross, Tobias Kainz, Bernhard Institute for Computer Graphics and Vision Graz University of Technology Inffeldgasse 16a/II 8010 Graz Austria

ISBN: (纸本)9783540689355

A common task in medical image analysis is the alignment of data from different sources, e.g., X-ray images and computed tomography (CT) data. Such a task is generally known as registration. We demonstrate the applicability of automatic differentiation (AD) techniques to a class of 2D/3D registration problems which are highly computationally intensive and can therefore greatly benefit from a parallel implementation on recent graphics processing units (GPUs). However, being designed for graphics applications, GPUs have some restrictions which conflict with requirements for reverse mode AD, in particular for taping and TBR analysis. We discuss design and implementation issues in the presence of such restrictions on the target platform and present a method which can register a CT volume data set (512 × 512 × 288 voxels) with three X-ray images (512 × 512 pixels each) in 20 seconds on a GeForce 8800GTX graphics card. © 2008 Springer-Verlag Berlin Heidelberg.

关键词： graphics processing unit

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Probabilistic visual tracking using global and local object's information

Probabilistic visual tracking using global and local object'...

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International Conference on computer science and Software Engineering, CSSE 2008

作者： Gao, Lin Liu, Zhifang Tang, Peng Image and Graphics Institute Computer Science Department Sichuan University Chengdu 610065 China

ISBN: (纸本)9780769533360

This paper presents a robust visual tracking algorithm by exploiting global and local object's information under a particle filter tracking framework. The proposed algorithm utilize a tow-stage cascade scheme to update the particles within the state space in a coarse to fine manner. At the first stage, the object state is estimated by a coarse search using global color statistics. Then a refined estimate is achieved through exploring the local binary pattern feature. To overcome the problem of poor priors in the conventional particle filter which uses system transition as the proposal distribution, we use the state estimation made at the first stage to construct the proposal distribution that seamlessly integrates the current observation. Experimental results demonstrate the efficiency and accuracy of the proposed algorithm. © 2008 IEEE.

关键词： Local binary pattern

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A stochastic approach based Bayesian salient motion segmentation method

A stochastic approach based Bayesian salient motion segmenta...

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International Conference on computer science and Software Engineering, CSSE 2008

作者： Tang, Peng Gao, Lin Sheng, Peng Image and Graphics Institute Computer Science Department Sichuan University Chengdu 610065 China

ISBN: (纸本)9780769533360

Moving object segmentation techniques are fundamental and crucial for video surveillance. In this paper, we abandoned the traditional background differential model approach which ignores the foreground modeling, and address this problem under the Bayesian framework. Our major contribution can be summarized as, modeling the background and foreground competitively to augment the segmentation accuracy, implementing the prior information to enforce spatial-temporal consistency, and introducing the Monte Carlo importance sampling techniques which effectively reduces the computation complexity while guarantees the expected veracity. Promising results demonstrate the potentials of the proposed framework. © 2008 IEEE.

关键词： Importance sampling

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A User Guidance Approach for Passive Haptic Environments 14

A User Guidance Approach for Passive Haptic Environments

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14th Eurographics Symposium on Virtual Environments, EGVE 2008

作者： Steinicke, F. Welzel, H. Bruder, G. Hinrichs, K. Visualization and Computer Graphics Research Group Institute of Computer Science Westfälische Wilhelms-Universität Münster Germany

ISBN: (纸本)9783905673661

Traveling through virtual environments (VEs) by means of real walking is a challenging task since usually the size of the virtual world exceeds the size of the tracked interaction space. Redirected walking is one concept to solve this problem by guiding the user on a physical path which differs from the path the user visually perceives, for example, in head-mounted display (HMD) *** user can be redirected to certain locations in the physical space, in particular to real proxy objects which provide passive feedback. In such passive haptic environments, any number of virtual objects can be mapped to proxy objects having similar haptic properties, i. e., size, shape and texture. When the user is guided to corresponding proxy objects, s/he can sense virtual objects by touching their real world counterparts. Therefore it is vital to predict the user’s movements in the virtual world in order to recognize the target location. Based on the prediction a transformed path can be determined in the physical space on which the user is guided to the desired proxy object. In this paper we present concepts how a user’s path can be predicted reliably and how a corresponding path to a desired proxy object can be derived on which the user does not observe inconsistencies between vision and proprioception. © The Eurographics Association 2008.

关键词： Virtual reality

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eKnowledge pepositories in eLearning 2.0: UNITE - A European-wide network of schools

eKnowledge pepositories in eLearning 2.0: UNITE - A European...

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7th International Conference on Web Based Learning, ICWL 2008

作者： Hornung, Christoph Granic, Andrina Cukušic, Maja Nazemi, Kawa Fraunhofer Institute for Computer Graphics Darmstadt Germany Faculty of Science University of Split Split Croatia

ISBN: (纸本)3540850325

The upcoming Web 2.0 technologies change the aspects of eLearning fundamentally. The traditional paradigm of classroom teaching and homework learning will develop further towards sharing experiences and knowledge in word-wide social communities. Moreover, knowledge capturing in ambient environments gains more and more importance. These aspects characterize the so-called eLearning 2.0. This paper describes a prototype of an eLearning 2.0 system covering the different aspects such as platform, pedagogy and scenarios. The concepts presented here have been applied in the EU-project UNITE. The implementation of this system in the setting of a European network of fourteen schools is presented as an iterative four stage process, covering scenario planning and implementation, validation in addition to platform and process improvement. Achieved intermediate results from the first iteration of the implementation process are discussed and future work is presented. © 2008 Springer-Verlag Berlin Heidelberg.

关键词： Teaching

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Analyses of human sensitivity to redirected walking 08

Analyses of human sensitivity to redirected walking

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VRST 2008 ACM Symposium on Virtual Reality Software and Technology

作者： Steinicke, Frank Bruder, Gerd Jerald, Jason Frenz, Harald Lappe, Markus Visualization and Computer Graphics Group Department of Computer Science WWU Münster Germany Effective Virtual Environments Group Department of Computer Science UNC Chapel Hill United States Psychology Department II WWU Münster Germany

ISBN: (纸本)9781595939517

Redirected walking allows users to walk through large-scale immersive virtual environments (IVEs) while physically remaining in a reasonably small workspace by intentionally injecting scene motion into the IVE. In a constant stimuli experiment with a twoalternative-forced-choice task we have quantified how much humans can unknowingly be redirected on virtual paths which are different from the paths they actually walk. 18 subjects have been tested in four different experiments: (E1a) discrimination between virtual and physical rotation, (E1b) discrimination between two successive rotations, (E2) discrimination between virtual and physical translation, and discrimination of walking direction (E3a) without and (E3b) with start-up. In experiment E1a subjects performed rotations to which different gains have been applied, and then had to choose whether or not the visually perceived rotation was greater than the physical rotation. In experiment E1b subjects discriminated between two successive rotations where different gains have been applied to the physical rotation. In experiment E2 subjects chose if they thought that the physical walk was longer than the visually perceived scaled travel distance. In experiment E3a subjects walked a straight path in the IVE which was physically bent to the left or to the right, and they estimate the direction of the curvature. In experiment E3a the gain was applied immediately, whereas the gain was applied after a start-up of two meters in experiment E3b. Our results show that users can be turned physically about 68% more or 10% less than the perceived virtual rotation, distances can be up-or down-scaled by 22%, and users can be redirected on an circular arc with a radius greater than 24 meters while they believe they are walking straight. Copyright 2008 ACM.

关键词： Rotation

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Enhancing textured digital elevation models using photographs 4

Enhancing textured digital elevation models using photograph...

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4th International Symposium on 3D Data Processing, Visualization and Transmission, 3DPVT 2008

作者： Schneider, Martin Klein, Reinhard Institute of Computer Science II University of Bonn Römerstrasse 164 Bonn53117 Germany

We present a method for enhancing the visual quality of existing digital elevation models textured with orthophotos, using a sparse set of unordered, high resolution photographs. After an initial manual selection of correspondence points, we automatically register the input photographs to the given terrain data set using robust imagebased modeling techniques. To combine the geo-registered images on the terrain surface, we propose a compositing algorithm that ensures smooth transitions between the images while at the same time preserving the fine details. The resulting textures are inserted into the quadtree representation of a terrain rendering engine to allow an efficient real-time visualization. We demonstrate our method on an HRSC terrain data set and a collection of high resolution photos of Turtmann valley in Switzerland. © 2008 Georgia institute of Technology.

关键词： Geomorphology

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Characterization of spatial coating layer formation - definition of a representative sample size

Characterization of spatial coating layer formation - defini...

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TAPPI Advanced Coating Fundamentals Symposium

作者： Kritzinger, J. Hirn, U. Donoser, M. Bauer, W. Institute for Paper Pulp and Fiber Technology - IPZ Graz University of Technology Kopernikusgasse 24/II A-8010 Graz Austria Institute for Computer Graphics and Vision - ICG Graz University of Technology Inffeldgasse 16/II A-8010 Graz Austria

ISBN: (纸本)1595101748

Statistically representative analysis of the coating layer is important if the coating structures of differently coated sheets are to be compared. State of the art measuring techniques used to evaluate parameters of coating structures are limited in their sample size. The investigation of paper cross sections with 2D analysis methods is usually in the range of some millimeters of sample length. 3D measuring techniques are limited to a sample area of a few square millimeters. Therefore a representative analysis of coating structures demands the definition of a required sample size and number of samples. This paper presents the results of a repeatability experiment designed to evaluate the necessary sample size and the number of samples for a representative evaluation of coating layer structures. The experiment was carried out with a serial sectioning technique on a 135 g/m2 woodfree coated paper. The discussion regarding the required sample size shows that an area of 5 mm 2 represents the properties of local coating thickness distributions. Furthermore, it is shown that - having a sample area of 5 mm2 - 3-5 samples have to be analyzed to obtain representative and stable results for mean, standard deviation and skewness of coating thickness and base sheet caliper distributions.

关键词： Coatings

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