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2nd International Symposium on Combinatorial Optimization, ISCO 2012

作者： Ruthmair, Mario Raidl, Günther R. Institute of Computer Graphics and Algorithms Vienna University of Technology Vienna Austria

ISBN: (纸本)9783642321467

We present mixed integer programming approaches for optimally solving a combinatorial optimization problem arising in network design with additional quality of service constraints. The rooted delay- and delay-variation- constrained Steiner tree problem asks for a cost-minimal Steiner tree satisfying delay-constraints from source to terminals and a maximal variation-bound between particular terminal path-delays. Our MIP models are based on multi-commodity-flows and a layered graph transformation. For the latter model we propose some new sets of valid inequalities and an efficient separation method. Presented experimental results indicate that our layered graph approaches clearly outperform the flow-based model. © 2012 Springer-Verlag.

关键词： Combinatorial optimization

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Variable neighborhood search and GRASP for three-layer hierarchical ring network design

Variable neighborhood search and GRASP for three-layer hiera...

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12th International Conference on Parallel Problem Solving from Nature, PPSN 2012

作者： Schauer, Christian Raidl, Günther R. Institute of Computer Graphics and Algorithms Vienna University of Technology Vienna Austria

ISBN: (纸本)9783642329364

We introduce the Three-Layer Hierarchical Ring Network Design Problem, which arises especially in the design of large telecommunication networks. The aim is to connect nodes that are assigned to three different layers using rings of bounded length. We present tailored Variable Neighborhood Search (VNS) and GRASP approaches to solve large instances of this problem heuristically, and discuss computational results indicating the VNS' superiority. © 2012 Springer-Verlag.

关键词： Network layers

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Auto splats: Dynamic point cloud visualization on the GPU

Auto splats: Dynamic point cloud visualization on the GPU

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12th Eurographics Symposium on Parallel graphics and Visualization, EG PGV 2012

作者： Preiner, Reinhold Jeschke, Stefan Wimmer, Michael Institute of Computer Graphics and Algorithms Vienna University of Technology Austria

ISBN: (纸本)9783905674354

Capturing real-world objects with laser-scanning technology has become an everyday task. Recently, the acquisition of dynamic scenes at interactive frame rates has become feasible. A high-quality visualization of the resulting point cloud stream would require a per-frame reconstruction of object surfaces. Unfortunately, reconstruction computations are still too time-consuming to be applied interactively. In this paper we present a local surface reconstruction and visualization technique that provides interactive feedback for reasonably sized point clouds, while achieving high image quality. Our method is performed entirely on the GPU and in screen space, exploiting the efficiency of the common rasterization pipeline. The approach is very general, as no assumption is made about point connectivity or sampling density. This naturally allows combining the outputs of multiple scanners in a single visualization, which is useful for many virtual and augmented reality applications. © The Eurographics Association 2012.

关键词： Visualization

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Lecture Notes in computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics): Preface

Lecture Notes in Computer Science (including subseries Lectu...

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Lecture Notes in computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) 2013年 7831 LNCS卷 V-VI页

作者： Krawiec, Krzysztof Moraglio, Alberto Hu, Ting Etaner-Uyar, A. Şima Hu, Bin Poznan University of Technology Institute of Computing Science Piotrowo 2 60-965 Poznań Poland University of Birmingham School of Computer Science Edgbaston Birmingham B15 2TT United Kingdom Dartmouth College Geisel School of Medicine Hanover NH 03755 United States Istanbul Technical University Department of Computer Engineering Masla 34469 Istanbul Turkey Vienna University of Technology Institute of Computer Graphics and Algorithms 1040 Vienna Austria

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A variable neighborhood search approach for the two-echelon location-routing problem

A variable neighborhood search approach for the two-echelon ...

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12th European Conference on Evolutionary Computation in Combinatorial Optimization, EvoCOP 2012

作者： Schwengerer, Martin Pirkwieser, Sandro Raidl, Günther R. Institute of Computer Graphics and Algorithms Vienna University of Technology Vienna Austria Destion - IT Consulting OG Vienna Austria

ISBN: (纸本)9783642291234

We consider the two-echelon location-routing problem (2E-LRP), a well-known problem in freight distribution arising when establishing a two-level transport system with limited capacities. The problem is a generalization of the location routing problem (LRP), involving strategic (location), tactical (allocation) and operational (routing) decisions at the same time. We present a variable neighborhood search (VNS) based on a previous successful VNS for the LRP, accordingly adapted as well as extended. The proposed algorithm provides solutions of high quality in short time, making use of seven different basic neighborhood structures parameterized with different perturbation size leading to a total of 21 specific neighborhood structures. For intensification, two consecutive local search methods are applied, optimizing the transport costs efficiently by considering only recently changed solution parts. Experimental results clearly show that our method is at least competitive regarding runtime and solution quality to other leading approaches, also improving upon several best known solutions. © 2012 Springer-Verlag.

关键词： Location

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Practical spectral photography

Practical spectral photography

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33rd Annual Conference on European Association for computer graphics, EUROgraphics 2012

作者： Habel, Ralf Kudenov, Michael Wimmer, Michael Institute of Computer Graphics and Algorithms Vienna University of Technology Austria Optical Detection Lab. University of Arizona United States

We introduce a low-cost and compact spectral imaging camera design based on unmodified consumer cameras and a custom camera objective. The device can be used in a high-resolution configuration that measures the spectrum of a column of an imaged scene with up to 0.8 nm spectral resolution, rivalling commercial non-imaging spectrometers, and a mid-resolution hyperspectral mode that allows the spectral measurement of a whole image, with up to 5 nm spectral resolution and 120×120 spatial resolution. We develop the necessary calibration methods based on halogen/fluorescent lamps and laser pointers to acquire all necessary information about the optical system. We also derive the mathematical methods to interpret and reconstruct spectra directly from the Bayer array images of a standard RGGB camera. This objective design introduces accurate spectral remote sensing to computational photography, with numerous applications in color theory, colorimetry, vision and rendering, making the acquisition of a spectral image as simple as taking a high-dynamic-range image. © 2012 The Author(s).

关键词： Cameras

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Image segmentation based on active contours without edges

Image segmentation based on active contours without edges

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2012 IEEE 8th International Conference on Intelligent computer Communication and Processing, ICCP 2012

作者： Morar, Anca Moldoveanu, Florica Gröller, Eduard Faculty of Automatic Control and Computers University POLITEHNICA of Bucharest Romania Institute of Computer Graphics and Algorithms Vienna University of Technology Austria

ISBN: (纸本)9781467329514

There are a lot of image segmentation techniques that try to differentiate between background and object pixels, but many of them fail to discriminate between different objects that are close to each other. Some image characteristics like low contrast between background and foreground or inhomogeneity within the objects increase the difficulty of correctly segmenting images. We designed a new segmentation algorithm based on active contours without edges. We also used other image processing techniques such as nonlinear anisotropic diffusion and adaptive thresholding in order to overcome the images' problems stated above. Our algorithm was tested on very noisy images, and the results were compared to those obtained with known methods, like segmentation using active contours without edges and graph cuts. The new technique led to very good results, but the time complexity was a drawback. However, this drawback was significantly reduced with the use of graphical programming. Our segmentation method has been successfully integrated in a software application whose aim is to segment the bones from CT datasets, extract the femur and produce personalized prostheses in hip arthroplasty. © 2012 IEEE.

关键词： Image segmentation

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Applying (hybrid) metaheuristics to fuel consumption optimization of hybrid electric vehicles

Applying (hybrid) metaheuristics to fuel consumption optimiz...

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EvoCOMNET, EvoCOMPLEX, EvoFIN, EvoGAMES, EvoHOT, EvoIASP, EvoNUM, EvoPAR, EvoRISK, EvoSTIM, and EvoSTOC, EvoApplications 2012

作者： Krenek, Thorsten Ruthmair, Mario Raidl, Günther R. Planer, Michael Institute for Powertrains and Automotive Technology Vienna University of Technology Vienna Austria Institute of Computer Graphics and Algorithms Vienna University of Technology Vienna Austria

ISBN: (纸本)9783642291777

This work deals with the application of metaheuristics to the fuel consumption minimization problem of hybrid electric vehicles (HEV) considering exactly specified driving cycles. A genetic algorithm, a downhill-simplex method and an algorithm based on swarm intelligence are used to find appropriate parameter values aiming at fuel consumption minimization. Finally, the individual metaheuristics are combined to a hybrid optimization algorithm taking into account the strengths and weaknesses of the single procedures. Due to the required time-consuming simulations it is crucial to keep the number of candidate solutions to be evaluated low. This is partly achieved by starting the heuristic search with already meaningful solutions identified by a Monte-Carlo procedure. Experimental results indicate that the implemented hybrid algorithm achieves better results than previously existing optimization methods on a simplified HEV model. © 2012 Springer-Verlag.

关键词： Genetic algorithms

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Classification of gothic and baroque architectural elements

Classification of gothic and baroque architectural elements

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2012 19th International Conference on Systems, Signals and Image Processing, IWSSIP 2012

作者： Shalunts, Gayane Haxhimusa, Yll Sablatnig, Robert Institute of Computer Aided Automation Computer Vision Lab. Vienna University of Technology Austria Institute of Computer Graphics and Algorithms Pattern Recognition and Image Processing Lab. Vienna University of Technology Austria

ISBN: (纸本)9783200023284

Architectural elements are the components and details of buildings. Their unique set, combination, design, construction technique form the architectural style of buildings. Building facade classification by architectural styles is viewed as a task of classifying separate architectural structural elements. In the scope of building facade architectural style classification the current paper targets the problem of classification of Gothic and Baroque architectural elements called tracery, pediment and balustrade. Since certain gradient directions dominate on the shape of each architectural element, discrimination between dominating gradients means classification of architectural elements and thus architectural styles. We use local features to describe gradient directions. Our approach is based on clustering and learning of local features and yields a high classification rate. © 2012 institute of Telecommunica.

关键词： Classification (of information)

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Porosity maps - Interactive exploration and visual analysis of porosity in carbon fiber reinforced polymers

Porosity maps - Interactive exploration and visual analysis ...

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14th Eurographics Conference on Visualization 2012, EuroVis 2012

作者： Reh, A. Plank, B. Kastner, J. Gröller, E. Heinzl, C. University of Applied Sciences Upper Austria Campus Wels Austria Vienna University of Technology Institute of Computer Graphics and Algorithms Vienna Austria

In this work a novel method for the characterization of porosity in carbon fiber reinforced polymers (CFRP) is presented. A visualization pipeline for the interactive exploration and visual analysis of CFRP specimens is developed to enhance the evaluation workflow for non-destructive testing (NDT) practitioners based on specified tasks. Besides quantitative porosity determination and the calculation of local pore properties, i.e., volume, surface, dimensions and shape factors, we employ a drill-down approach to explore pores in a CFRP specimen. We introduce Porosity Maps (PM), to allow for a fast porosity evaluation of the specimen. Pores are filtered in two stages. First a region of interest is selected in the porosity maps. Second, pores are filtered with parallel coordinates according to their local properties. Furthermore a histogram-based best-viewpoint widget was implemented to visualize the quality of viewpoints on a sphere. The advantages of our approach are demonstrated using real world CFRP specimens. We are able to show that our visualization-driven approach leads to a better evaluation of CFRP components than existing reference methods. © 2012 The Author(s).

关键词： Porosity

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