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Conference on Multimedia Content Access - algorithms and Systems II

作者： Hare, Jonathon S. Lewis, Paul H. Gordon, Layla Hart, Glen Univ Southampton Sch Elect & Comp Sci Southampton SO17 1BJ Hants England Ordnance Survey Southampton SO16 4GU Hants England

ISBN: (纸本)9780819469922

The MapSnapper project aimed to develop a system for robust matching of low-quality images of a paper map taken from a mobile phone against a high quality digital raster representation of the same map. The paper presents. a novel methodology for performing content-based image retrieval and object recognition from query images that have been degraded by noise and subjected to, transformations through the imaging system. In addition the paper also provides an insight into the evaluation-driven development process that was used to incrementally improve the matching performance until the design specifications were met.

关键词： image matching mobile device interest points salient regions local descriptors geometric matching constraints robust algorithms

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robust adaptive meshes for implicit surfaces

Robust adaptive meshes for implicit surfaces

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19th Brazilian Symposium on Computer Graphics and Image Processing (SIBGRAPI 2006)

作者： Paiva, Afonso Lopes, Helio Lewiner, Thomas de Figueiredo, Luiz Henrique PUC Dept Math Rio De Janeiro Brazil IMPA Rio De Janeiro Brazil

ISBN: (纸本)0769526861

This work introduces a robust algorithm for computing good polygonal approximations of implicit surfaces, where robustness entails recovering the exact topology of the implicit surface. Furthermore, the approximate triangle mesh adapts to the geometry and to the topology of the real implicit surface. This method generates an octree subdivided according to the interval evaluation of the implicit function in order to guarantee the robustness, and to the interval automatic differentiation in order to adapt the octree to the geometry of the implicit surface. The triangle mesh is then generated from that octree through an enhanced dual marching.

关键词： implicit surface dual marching cubes robust algorithms geometric modelling

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Recent progress in exact geometric computation

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JOURNAL OF LOGIC AND ALGEBRAIC PROGRAMMING 2005年第1期64卷 85-111页

作者： Li, C Pion, S Yap, CK NYU Courant Inst Math Sci New York NY 10012 USA

Computational geometry has produced an impressive wealth of efficient algorithms. The robust implementation of these algorithms remains a major issue. Among the many proposed approaches for solving numerical non-robustness, exact geometric computation (EGC) has emerged as one of the most successful. This survey describes recent progress in EGC research in three key areas: constructive zero bounds, approximate expression evaluation and numerical filters. (c) 2004 Published by Elsevier Inc.

关键词： exact geometric computation constructive zero bounds non-robustness problems robust algorithms approximate expression evaluation precision-driven computation numerical filters nterval arithmetic C plus plus libraries

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robust algorithms for constructing strongly convex hulls in parallel

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THEORETICAL COMPUTER SCIENCE 2002年第1期289卷 277-295页

作者： Chen, W Wada, K Kawaguchi, K Nagoya Inst Technol Syowa Ku Nagoya Aichi 4668555 Japan Osaka Inst Technol Hirakata Osaka 57301 Japan

Given a set S of n points in the plane, an E-strongly convex delta-hull of S is defined as a convex polygon P with the vertices taken from S such that no point of S lies farther than 6 outside P and such that even if the vertices of P are perturbed by as much as e, P remains convex. This paper presents the first parallel robust method for this generalized convex hull problem (note that the convex hull of S is the 0-strongly convex 0-hull of S). We show that an e-strongly convex O(epsilon + beta)-hull of S can be constructed in O(log(3) n) time using n processors with imprecise computations, where beta is the error unit of primitive operations. This result also implies an improved sequential algorithm. Our algorithm consists of two parts: (1) computing a convex O(epsilon + beta)-hull of n points, in O(log(3) n) time using n processors, and (2) constructing an E-strongly convex O(epsilon + beta)-hull of a convex polygon with n vertices, in O(log(2) n) time with n processors. We also find an approximate bridge of two sets with n points each, in O(log(2) n) time using n processors, which we use as a subroutine. All these algorithms are fundamental and have their own applications. The parallel computational model in this paper is the EREW PRAM. (C) 2002 Elsevier Science B.V. All rights reserved.

关键词： computational geometry robust algorithms convex hull PRAM computational model

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Malguki:: an RSSI based ad hoc location algorithm

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MICROPROCESSORS AND MICROSYSTEMS 2004年第8期28卷 403-409页

作者： Arias, J Zuloaga, A Lázaro, J Andreu, J Astarloa, A Univ Basque Country Fac Engn Dept Elect & Telecommun Bilbao 48013 Spain

The problem of finding the location of a node in wireless networks has been a research interest in the last years. In environments where the GPS does not work, the estimation of a node position using only RF signals is not a trivial task. Although some other systems have been proposed so far, using ultrasonic signals, IR, etc. But those require additional hardware that is only to be used for location finding. This article describes an algorithm, which computes the location of a node using noisy distance estimations. Thus, the restriction on distance exactitude can be relaxed and RF signal based distance estimations may be used to estimate the node location. (C) 2004 Elsevier B.V. All rights reserved.

关键词： RSSI location wireless sensor networks robust algorithms

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robust ML wideband beamforming in reverberant fields

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2003年第2期51卷 338-349页

作者： Di Claudio, ED Parisi, R Univ Roma La Sapienza INFOCOM Dept Rome Italy

Adaptive beamforming of sensor arrays immersed into reverberant fields can easily result in the cancellation of the useful signal because of the temporal correlation existing among the direct and the reflected path signals. Wideband beamforming can somewhat mitigate this phenomenon, but adaptive solutions based on the minimum variance (MV) criterion remain nonrobust in many practical applications, such as multimedia systems, underwater acoustics, and seismic prospecting. In this paper, a steered wideband adaptive beamformer, optimized by a novel concentrated maximum likelihood (NIL) criterion in the frequency domain, is presented and discussed in the light of a very general reverberation model. It is shown that NIL beamforming can alleviate the typical cancellation problems encountered by adaptive MV beamforming and preserve the intelligibility of a wideband and colored source signal under interference, reverberation, and propagation mismatches.\ The difficult optimization of the NIL cost function, which incorporates a robustness constraint to prevent signal cancellation, is recast as an iterative least squares problem through the concept of descent in the neuron space, which was originally developed for the training of multilayer neural networks. Finally, experiments with computer-generated and real-world data demonstrate the superior performance of the proposed beamformer with respect to its MV counterpart.

关键词： acoustics adaptive beamforming cepstrum maximum likelihood minimum variance multipath neural network learning reverberation ridge regression robust algorithms sensor arrays wideband coherent focusing

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A geometry modeling system for ray tracing or particle transport Monte Carlo simulation

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COMPUTER PHYSICS COMMUNICATIONS 2003年第1期150卷 21-30页

作者： Popescu, LM Natl Inst R&D Environm Environm Radioact Lab Bucharest 77703 Romania

The principles of a geometry modeling system for ray tracing or Monte Carlo particle transport simulation are presented. The model uses the boundary representation of volumes and was developed using object oriented programming. The surface is adopted as the basic element in the model. Complex structures are described using the derived concept of compound surfaces. Particle tracking exceptions caused by floating point rounding errors are discussed and robust algorithms that use geometrical reasoning to address these problems are presented. (C) 2002 Elsevier Science B.V. All rights reserved.

关键词： Monte Carlo particle transport geometry modeling boundary representation robust algorithms

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Stability number of bull- and chair-free graphs revisited

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DISCRETE APPLIED MATHEMATICS 2003年第1期131卷 39-50页

作者： Brandstädt, A Hoàng, CT Le, VB Univ Rostock Fachbereich Informat D-18051 Rostock Germany Wilfrid Laurier Univ Dept Phys & Comp Waterloo ON N2L 3C5 Canada

De Simone showed that prime bull- and chair-free graphs containing a co-diamond are either bipartite or an induced cycle of odd length at least five. Based on this result, we give a complete structural characterization of prime (bull,chair)-free graphs having stability number at least four as well as of (bull,chair,co-chair)-free graphs. This implies constant-bounded clique width for these graph classes which leads to linear time algorithms for some algorithmic problems. Moreover, we obtain a robust O(nm) time algorithm for the maximum weight stable set problem on bull- and chair-free graphs without testing whether the (arbitrary) input graph is bull- and chair-free. This improves previous results with respect to structural insight, robustness and time bounds. (C) 2003 Elsevier B.V. All rights reserved.

关键词： modular decomposition prime graphs maximum weight stable set problem on graphs Bull- and chair-free graphs robust algorithms clique width of graphs

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Learning a statistical 3D geometric head model

Learning a statistical 3D geometric head model

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Conference on Videometrics VII

作者： Lai, SH Chen, YL Natl Tsing Hua Univ Dept Comp Sci Hsinchu 300 Taiwan

ISBN: (纸本)0819448133

Statistical modeling of signal/image data has been used extensively for recognition and estimation. Principal component analysis was very popular for the statistical signal modeling and analysis. In this paper, we present a system to build a 3D statistical head model from incomplete data. In this system, we first transformed the 3D head scan data points into a cylindrical coordinate to obtain 2D surface maps. After these 2D surface maps were aligned, we computed the associated mean vector and covariance matrix. Then, the principal component analysis technique was applied to compute the principal components and the corresponding eigenvalues of the covariance matrix. Experimental results are given to show the 3D head shape variations from the computed 3D statistical model.

关键词： statistical head model point distribution models principal component analysis surface registration robust algorithms missing data

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Stability number of bull- and chair-free graphs revisited

Stability number of bull- and chair-free graphs revisited

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2nd International Colloquium Days of Messina Data Processing on algorithms of Graphs (JIM 2000)

作者： Brandstädt, A Hoàng, CT Le, VB Univ Rostock Fachbereich Informat D-18051 Rostock Germany Wilfrid Laurier Univ Dept Phys & Comp Waterloo ON N2L 3C5 Canada

关键词： modular decomposition prime graphs maximum weight stable set problem on graphs Bull- and chair-free graphs robust algorithms clique width of graphs

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