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Optimal constrained multi-degree reduction of Bézier curves with explicit expressions based on divide and conquer

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第4期10卷 577-582页

作者： Lian ZHOU Guo-jin WANG Institute of Computer Graphics and Image Processing State Key Lab of CAD & CG Zhejiang University Hangzhou 310027 China

We decompose the problem of the optimal multi-degree reduction of Bézier curves with corners constraint into two simpler subproblems, namely making high order interpolations at the two endpoints without degree reduction, and doing optimal degree reduction without making high order interpolations at the two endpoints. Further, we convert the second subproblem into multi-degree reduction of Jacobi polynomials. Then, we can easily derive the optimal solution using orthonormality of Jacobi polynomials and the least square method of unequally accurate measurement. This method of 'divide and conquer' has several advantages including maintaining high continuity at the two endpoints of the curve, doing multi-degree reduction only once, using explicit approximation expressions, estimating error in advance, low time cost, and high precision. More importantly, it is not only deduced simply and directly, but also can be easily extended to the degree reduction of surfaces. Finally, we present two examples to demonstrate the effectiveness of our algorithm.

关键词： Bezier curves Multi-degree reduction Divide and conquer

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A new method in highway route design:joining circular arcs by a single C-Bézier curve with shape parameter

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第4期10卷 562-569页

作者： Hua-hui CAI Guo-jin WANG Institute of Computer Graphics and Image Processing State Key Lab of CAD & CG Zhejiang University Hangzhou 310027 China

We constructed a single C-Bezier curve with a shape parameter for G^2 joining two circular arcs. It was shown that an S-shaped transition curve, which is able to manage a broader scope about two circle radii than the Bezier curves, has no curvature extrema, while a C-shaped transition curve has a single curvature extremum. Regarding the two kinds of curves, specific algorithms were presented in detail, strict mathematical proofs were given, and the effectiveness of the method was shown by examples This method has the following three advantages：（1） the pattern is unified; （2） the parameter able to adjust the shape of the transition curve is available; （3） the transition curve is only a single segment, and the algorithm can be formulated as a low order equation to be solved for its positive root. These advantages make the method simple and easy to implement.

关键词： Transition curve C-Bezier curve Monotone curvature Shape parameter

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Space-Time Correlation Properties of a 3D Two-Sphere Model for Non-Isotropic MIMO Mobile-to-Mobile Channels

Space-Time Correlation Properties of a 3D Two-Sphere Model f...

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2010 IEEE Global Telecommunications Conference GLOBECOM 2010

作者： Yi Yuan Xiang Cheng Cheng-Xiang Wang David I. Laurenson Xiaohu Ge Feng Zhao Joint Research Institute of Signal and Image Processing Heriot-Watt University Edinburgh UK School of Electronics Engineering and Computer Science Peking University Beijing China Joint Research Institute of Signal and Image Processing University of Edinburgh Edinburgh UK Department of Electronics and Information Engineering Huazhong University of Science and Technology Wuhan China Department of Science and Technology Guilin University of Electronic and Technology Guilin China

This paper proposes a novel three-dimensional (3D) two-sphere regular-shaped geometry-based stochastic model (RS-GBSM) with only double-bounced rays for non-isotropic scattering narrowband multiple-input multiple-output (MIMO) mobile-to-mobile (M2M) channels. The proposed 3D model has the ability to investigate the joint impact of both the azimuth angle and elevation angle on channel statistics. Based on the proposed model, the space-time (ST) correlation function (CF) is derived and the impact of some important parameters on the resulting ST CF is investigated. Numerical results show that the 3D model results in lower ST correlations than the corresponding 2D model.

关键词： Correlation Three dimensional displays MIMO Solid modeling Scattering Azimuth Antennas

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Testing Cross-Platform Streaming of Video Games over Wired and Wireless LANs

Testing Cross-Platform Streaming of Video Games over Wired a...

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International Conference on Advanced Information Networking and Applications Workshops (AINAW)

作者： Audrius Jurgelionis Francesco Bellotti Alessandro De Gloria Jukka-Pekka Laulajainen Philipp Fechteler Peter Eisert Haggai David Department of Biophysical and Electronic Engineering University of Genoa Genoa Italy Universita degli Studi di Genova Genova Liguria IT Converging Networks Laboratory VTT Technical Research Center of Finland Oulu Finland Computer Vision & Graphics Fraunhofer-Institute for Telecommunications Berlin Germany Computer Vision & Graphics Image Processing Department Heinrich-Hertz-Institute Fraunhofer Institute of Telecommunications Berlin Germany Converging Networks Laboratory VTT Technical Research Centre of Finland Oulu Finland R&D Department Exent Technologies Ltd. Petach Tikva Israel

In this paper we present a new cross-platform approach for video game delivery in wired and wireless local networks. The developed 3D streaming and video streaming approaches enable users to access video games on set top boxes and handheld devices that natively are not capable to run PC games. During the development of the distributed gaming system we have faced a number of challenges and problems posed by the hardware and network limitations. In order to solve these problems we have developed a multilevel testing methodology which is based on user assessment and technical measures for the system under development. In this paper we focus on the technical measures and instrumentation that we use for the system's performance measurement and testing. The benefits of our testing methodology are demonstrated through examples from the development and testing work.

关键词： Streaming media Games Wireless LAN System testing computer graphics Hardware Cloud computing Delay image coding computer architecture

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Evaluating the Response Time of Large Scale Content Adaptation Systems Using Performance Evaluation Process Algebra

Evaluating the Response Time of Large Scale Content Adaptati...

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IEEE International Conference on Communications (ICC)

作者： J. Ding J. Hillston D. I. Laurenson The University of Edinburgh Edinburgh Edinburgh GB Laboratory of Foundations of Computer Science School of Informatics University of Edinburgh Edinburgh UK Institute of Digital Communications Joint Research Institute of Signal & Image Processing School of Engineering University of Edinburgh Edinburgh UK

With the increasing diversity of content as well as user preferences, and the heterogeneity of devices and network technologies, content adaptation has been widely acknowledged as an effective strategy to deliver services and content to users in a variety of contexts. This paper presents an evaluation of the response time of large scale content adaptation systems being developed under the auspices of the Mobile VCE, using the high-level modelling formalism -performance evaluation process algebra (PEPA). The relevant factors of the system performance, including the operation speed of individual entities, loading and resource conditions of the system, are determined and analysed.

关键词： Delay Large-scale systems Algebra Mobile communication Informatics Context-aware services Performance analysis Velocity measurement Time measurement Communications Society

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EFFICIENT CLASSIFICATION FOR LARGE-SCALE PROBLEMS BY MULTIPLE LDA SUBSPACES

EFFICIENT CLASSIFICATION FOR LARGE-SCALE PROBLEMS BY MULTIPL...

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4th International Conference on computer Vision Theory and Applications

作者： Uray, Martina Roth, Peter M. Bischof, Horst Institute of Digital Image Processing Joanneum Research Austria Institute for Computer Graphics and Vision Graz University of Technology Austria

ISBN: (纸本)9789898111692

In this paper we consider the limitations of Linear Discriminative Analysis (LDA) when applying it for large-scale problems. Since LDA was originally developed for two-class problems the obtained transformation is sub-optimal if multiple classes are considered. In fact, the separability between the classes is reduced, which decreases the classification power. To overcome this problem several approaches including weighting strategies and mixture models were proposed. But these approaches are complex and computational expensive. Moreover, they were only tested for a small number of classes. In contrast, our approach allows to handle a huge number of classes showing excellent classification performance at low computational costs. The main idea is to split the original data into multiple sub-sets and to compute a single LDA space for each sub-set. Thus, the separability in the obtained subspaces is increased and the overall classification power is improved. Moreover, since smaller matrices have to be handled the computational complexity is reduced for both, training and classification. These benefits are demonstrated on different publicly available datasets. In particular, we consider the task of object recognition, where we can handle up to 1000 classes.

关键词： LDA image classification Large databases

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An efficient hierarchical segmentation approach for remote sensing images

An efficient hierarchical segmentation approach for remote s...

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MIPPR 2009 - Automatic Target Recognition and image Analysis: 6th International Symposium on Multispectral image processing and Pattern Recognition

作者： Kong, Dingke Wang, Guozhao Institute of Computer Graphics and Image Processing Department of Mathematics Zhejiang University Hangzhou 310027 China

ISBN: (纸本)9780819478061

Segmentation is one of the key problems in remote sensing image processing, and a cluster hierarchy is a powerful tool to analyze data on multiple scales. In this paper, we present an optimal hierarchical remote sensing image segmentation approach which is a combination of feature-based classification, multi-scale region merging and classification-based object refinement, and it is shown to have the following properties: 1) it gets better results on general remote sensing images;2) it offers a flexible segmentation hierarchy at a less computational cost. © 2009 Copyright SPIE - The International Society for Optical Engineering.

关键词： image segmentation

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New method in information processing for maintaining an efficient dynamic ordered set

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Science in China(Series F) 2009年第8期52卷 1292-1301页

作者： XIN ShiQing WANG GuoJin Institute of Computer Graphics and Image Processing Zhejiang University Hangzhou 310027 China State Key Laboratory of CAD & CG Zhejiang University Hangzhou 310027 China

This paper investigates how to maintain an efficient dynamic ordered set of bit strings, which is an important problem in the field of information search and information processing. Generally, a dynamic ordered set is required to support 5 essential operations including search, insertion, deletion, max-value retrieval and next-larger-value retrieval. Based on previous research fruits, we present an advanced data structure named rich binary tree （RBT）, which follows both the binary-search-tree property and the digital-search-tree property. Also, every key K keeps the most significant difference bit （MSDB） between itself and the next larger value among K＇s ancestors, as well as that between itself and the next smaller one among its ancestors. With the new data structure, we can maintain a dynamic ordered set in O（L） time. Since computers represent objects in binary mode, our method has a big potential in application. In fact, RBT can be viewed as a general-purpose data structure for problems concerning order, such as search, sorting and maintaining a priority queue. For example, when RBT is applied in sorting, we get a linear-time algorithm with regard to the key number and its performance is far better than quick-sort. What is more powerful than quick-sort is that RBT supports constant-time dynamic insertion/deletion.

关键词： information processing dynamic ordered set algorithms and data structures rich binary tree

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Monte Carlo realisation of a distributed multi-object fusion algorithm

Monte Carlo realisation of a distributed multi-object fusion...

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Sensor Signal processing for Defence (SSPD 2010)

作者： Murat Üney Simon Julier Daniel Clark Branko Ristić Department of Electrical Electronic & Computer Engineering School of Engineering & Physical Sciences Heriot-Watt University Edinburgh UK University College London London UK Joint Research Institute in Signal and Image Processing Heriot-Watt University Edinburgh UK ISR Division DSTO Australia Edinburgh SA Australia

We consider the problem of distributed target tracking in a multi-object, multi-sensor scenario in which the structure of the joint distribution of the estimate between different nodes is unknown. In this paper we present a preliminary implementation of Generalised Covariance Intersection (GCI) fusion rule for multi-object posteriors through a Monte Carlo realisation. We discuss the subtleties in the case of multi-object distributions and derive a scheme for sampling from Exponential Mixture Densities which are at the heart of the GCI. We demonstrate the improvement in localisation of multiple targets in a simulation scenario.

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On capacity of cognitive radio networks with average interference power constraints

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IEEE Transactions on Wireless Communications 2009年第4期8卷 1620-1625页

作者： Wang, Cheng-Xiang Hong, Xuemin Chen, Hsiao-Hwa Thompson, John Joint Research Institute for Signal and Image Processing School of Engineering and Physical Sciences Heriot-Watt University United Kingdom Department of Electrical and Computer Engineering University of Waterloo ON Canada Department of Engineering Science National Cheng Kung University Taiwan Joint Research Institute for Signal and Image Processing Institute for Digital Communications University of Edinburgh United Kingdom

Cognitive radio (CR) has been considered as a promising technology to improve the spectrum utilization. In this paper we analyze the capacity of a CR network with average received interference power constraints. Under the assumptions of uniform node placements and a simple power control scheme, the maximum transmit power of a target CR transmitter is characterized by its cumulative distribution function (CDF). We study two CR scenarios for future applications. The first scenario is called the CR based central access network, which aims at providing broadband access to CR devices. In the second scenario, the so-called CR assisted virtual multiple-input multiple-output (MIMO) network, CR is used to improve the access capability of a cellular system. The uplink ergodic channel capacities of both scenarios are derived and analyzed with an emphasis on understanding the impact of numbers of primary users and CR users on the capacity. Numerical and simulation results suggest that the CR based central access network is more suitable for less-populated rural areas where a relatively low density of primary receivers is expected;while the CR assisted virtual MIMO network performs better in urban environments with a dense population of mobile CR users. © 2006 IEEE.

关键词： Cognitive radio

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