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5th Eurographics Workshop on 3D Object Retrieval, EG 3DOR 2012

作者： Saavedra, J.M. Bustos, B. Schreck, T. Yoon, S. Scherer, M. KDW-PRISMA Research Group Department of Computer Science University of Chile Chile Data Analysis and Visualization Group University of Konstanz Germany Yonsei Institute of Convergence Technology Yonsei University Korea Republic of GRIS TU Darmstadt Germany

ISBN: (纸本)9783905674361

Since 3D models are becoming more popular, the need for effective methods capable of retrieving 3D models is becoming crucial. Current methods require an example 3D model as query. However, in many cases, such a query is not easy to get. An alternative is using a hand-drawn sketch as query. In this work, we present a new keyshape based approach named HKO-KASD for retrieving 3D models using rough sketches as queries. Our approach comprises two general steps. First, a global descriptor is used to determine the appropriate viewpoint for each model. Second, we apply a local matching process to determine the final ranking for an input sketch. To this end, we present a local descriptor capable of working with sketch representations. The global descriptors as well as the local descriptors rely on a set of keyshapes precomputed from 2D representations of 3D models and from the query sketch as well. We evaluate our method using the first-tier precision and compare it with current approaches (HELO, STELA). Our results show a significant increase in precision for many classes of 3D models. © The Eurographics Association 2012.

关键词： Self organizing maps

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Graph-based combinations of fragment descriptors for improved 3D object retrieval 12

Graph-based combinations of fragment descriptors for improve...

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3rd ACM Multimedia Systems Conference, MMSys'12

作者： Schreck, Tobias Scherer, Maximilian Walter, Michael Bustos, Benjamin Yoon, Sang Min Kuijper, Arjan Data Analysis and Visualization Group University of Konstanz Germany Interactive Graphics Systems Technische Universität Darmstadt Germany KDW+PRISMA Department of Computer Science University of Chile Chile Yonsei Institute of Convergence Technology Yonsei University Korea Republic of Fraunhofer Institute for Computer Graphics Research Darmstadt Germany

ISBN: (纸本)9781450311311

3D Object Retrieval is an important field of research with many application possibilities. One of the main goals in this research is the development of discriminative methods for similarity search. The descriptor-based approach to date has seen a lot of research attention, with many different extraction algorithms proposed. In previous work, we have introduced a simple but effective scheme for 3D model retrieval based on a spatially fixed combination of 3D object fragment descriptors. In this work, we propose a novel flexible combination scheme based on finding the best matching fragment descriptors to use in the combination. By an exhaustive experimental evaluation on established benchmark data we show the capability of the new combination scheme to provide improved retrieval effectiveness. The method is proposed as a versatile and inexpensive method to enhance the effectiveness of a given global 3D descriptor approach. © 2012 ACM.

关键词： Self organizing maps

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Liquidlike correlations in single-crystalline Y2Mo2O7: An unconventional spin glass

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Physical Review B 2014年第5期89卷 054433-054433页

作者： H. J. Silverstein K. Fritsch F. Flicker A. M. Hallas J. S. Gardner Y. Qiu G. Ehlers A. T. Savici Z. Yamani K. A. Ross B. D. Gaulin M. J. P. Gingras J. A. M. Paddison K. Foyevtsova R. Valenti F. Hawthorne C. R. Wiebe H. D. Zhou Department of Chemistry University of Manitoba Winnipeg Manitoba R3T 2N2 Canada Department of Physics and Astronomy McMaster University Hamilton Ontario L8S 4M1 Canada Department of Physics and Astronomy University of Waterloo Waterloo Ontario N2L 3G1 Canada Perimeter Institute for Theoretical Physics 31 Caroline Street North Waterloo Ontario N2L 2Y5 Canada School of Physics HH Wills Physics Laboratory University of Bristol Bristol BS8 1TL United Kingdom Indiana University 2401 Milo B. Sampson Lane Bloomington Indiana 47408 USA NIST Center for Neutron Research National Institute of Standards and Technology Gaithersburg Maryland 20899-6102 USA Department of Materials Science and Engineering University of Maryland College Park Maryland 20742 USA Quantum Condensed Matter Division Neutron Sciences Directorate Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA Neutron Data Analysis and Visualization Division Neutron Sciences Directorate Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA Canadian Neutron Beam Centre Chalk River Ontario K0J 1P0 Canada Canadian Institute for Advanced Research 180 Dundas St. W. Toronto Ontario M5G 1Z8 Canada Brockhouse Institute for Materials Research McMaster University Hamilton Ontario L8S 4M1 Canada Department of Chemistry University of Oxford Inorganic Chemistry Laboratory South Parks Road Oxford OX1 3QR United Kingdom ISIS Facility Rutherford Appleton Laboratory Chilton Didcot Oxfordshire OX11 0QX United Kingdom Institut für Theoretische Physik Goethe-Universität Frankfurt Frankfurt am Main 60438 Germany Department of Geological Sciences University of Manitoba Winnipeg Manitoba R3T 2N2 Canada Department of Chemistry University of Winnipeg 515 Portage Ave. Winnipeg Manitoba R3B 2E9 Canada Department of Physics and Astronomy University of Tennessee Knoxville Tennessee 37996-1200 USA National High Magnetic Field Laboratory Florida State University Tallahassee Florida 32306-4005 USA

The spin-glass behavior of Y2Mo2O7 has remained a puzzle for nearly three decades. Free of bulk disorder within the resolution of powder diffraction methods, it is thought that this material is a rare realization of a spin glass resulting from weak disorder such as bond disorder or local lattice distortions. Here we report on the single-crystal growth of Y2Mo2O7. Using neutron scattering, we present isotropic magnetic diffuse scattering occurring below the spin-glass transition. Our attempts to model the diffuse scattering using a computationally exhaustive search of a class of simple spin Hamiltonians show no agreement with the experimentally observed energy-integrated (diffuse) neutron scattering. This suggests that spin degrees of freedom are insufficient to describe this system. Indeed, a T2 temperature dependence in the heat capacity and density functional theory calculations hint at the presence of a significant frozen degeneracy in both the spin and orbital degrees of freedom resulting from spin-orbital coupling (Kugel-Khomskii type) and random fluctuations in the Mo environment at the local level.

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Diverse subgroup set discovery

Diverse subgroup set discovery

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作者： Van Leeuwen, Matthijs Knobbe, Arno Machine Learning Department of Computer Science Katholieke Universiteit Leuven Leuven Belgium Algorithmic Data Analysis Department of Information and Computer Sciences Universiteit Utrecht Utrecht Netherlands Leiden Institute of Advanced Computer Science Universiteit Leiden Leiden Netherlands

Large data is challenging for most existing discovery algorithms, for several reasons. First of all, such data leads to enormous hypothesis spaces, making exhaustive search infeasible. Second, many variants of essentially the same pattern exist, due to (numeric) attributes of high cardinality, correlated attributes, and so on. This causes top-k mining algorithms to return highly redundant result sets, while ignoring many potentially interesting results. These problems are particularly apparent with subgroup discovery (SD) and its generalisation, exceptional model mining. To address this, we introduce subgroup set discovery: one should not consider individual subgroups, but sets of subgroups. We consider three degrees of redundancy, and propose corresponding heuristic selection strategies in order to eliminate redundancy. By incorporating these (generic) subgroup selection methods in a beam search, the aim is to improve the balance between exploration and exploitation. The proposed algorithm, dubbed DSSD for diverse subgroup set discovery, is experimentally evaluated and compared to existing approaches. For this, a variety of target types with corresponding datasets and quality measures is used. The subgroup sets that are discovered by the competing methods are evaluated primarily on the following three criteria: (1) diversity in the subgroup covers (exploration), (2) the maximum quality found (exploitation), and (3) runtime. The results show that DSSD outperforms each traditional SD method on all or a (non-empty) subset of these criteria, depending on the specific setting. The more complex the task, the larger the benefit of using our diverse heuristic search turns out to be. © The Author(s) 2012.

关键词： Redundancy

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A tale of two systems: Flexibility of usage of Kraken and Nautilus at the National institute for Computational sciences

A tale of two systems: Flexibility of usage of Kraken and Na...

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1st Conference of the Extreme science and Engineering Discovery Environment: Bridging from the eXtreme to the Campus and Beyond, XSEDE12

作者： Szczepański, Amy F. Huang, Jian Ahern, Sean Fahey, Mark R. Remote Data Analysis and Visualization Center Electrical Engineering and Computer Science University of Tennessee 1520 Middle Drive Knoxville TN 37996-2250 United States Remote Data Analysis and Visualization Center National Institute for Computational Sciences University of Tennessee PO Box 2008 Oak Ridge TN 37831-6173 United States National Institute for Computational Sciences Industrial and Information Engineering University of Tennessee PO Box 2008 Oak Ridge TN 37831-6173 United States

ISBN: (纸本)9781450316026

The National institute for Computational sciences (NICS) at the University of Tennessee currently operates two computational resources for the eXtreme science and Engineering Discovery Environment (XSEDE), Kraken, a 112,896-core Cray XT5 for general purpose computation, and Nautilus, a 1,024-core SGI Altix UV 1000 for data analysis and visualization. We analyze a year's worth of accounting logs for Kraken and Nautilus to understand how users take advantage of these two systems and how analysis jobs differ from general HPC computation We find that researchers take advantage of the flexibility offered by these systems, running a wide variety of jobs at many scales and using the full range of core counts and available memory for their jobs. The jobs on Nautilus tend to use less walltime and more memory per core than the jobs run on Kraken. Additionally, researchers are more likely to run interactive jobs on Nautilus than on Kraken. Small jobs experience a good quality of service on both systems. This information can be used for the management and allocation of time on existing HPC and analysis systems as well as for planning for deploying future HPC and analysis systems. © 2012 ACM.

关键词： data visualization

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Topology exploration with hierarchical landscapes

Topology exploration with hierarchical landscapes

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Workshop at SIGGRAPH Asia 2012, WASA 2012

作者： Demir, Dogan Beketayev, Kenes Weber, Gunther H. Bremer, Peer-Timo Pascucci, Valerio Hamann, Bernd Scientific Computing and Imaging Institute School of Computing University of Utah United States Computational Research Divisition Lawrence Berkeley National Laboratory United States Center for Applied Scientific Computing Lawrence Livermore National Laboratory United States Institute for Data Analysis and Visualization Computer Science Department University of California Davis CA United States

ISBN: (纸本)9781450318358

Topological landscapes have been proposed as a visual metaphor for contour trees that does not require an understanding of the theory involved in defining contour trees. The idea is to create a representative terrain with the same topological structure as a given contour tree. This representation exploits the natural human ability to interpret topography and results in an intuitive visualization of otherwise abstract information. However, topological landscapes still suffer from some of the same limitations as traditional contour tree visualization. Most notable is the fact that for complex functions landscapes can quickly become highly complex, exceeding the limits of human comprehension as well as the available computing resources. To address this challenge, we propose a new framework for the dynamic creation and visualization of hierarchical topological landscapes. Our system provides an interactive visualization of complex functions by utilizing a hierarchical decomposition of the contour tree as well as focus+context type interactions. For three dimensional data, we link the landscape display to flexible isosurface extraction in order to correlate terrain features with their corresponding three dimensional counterparts. We demonstrate the utility and versatility of our approach on a variety of both low and high dimensional data sets. © 2012 ACM.

关键词： visualization

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Isosurface extraction from hybrid unstructured grids containing pentahedral elements

Isosurface extraction from hybrid unstructured grids contain...

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International Conference on computer Graphics Theory and Applications, GRAPP 2012 and International Conference on Information visualization Theory and Applications, IVAPP 2012

作者： Narayan, Akshay Sreevalsan-Nair, Jaya Gaither, Kelly Hamann, Bernd International Institute of Information Technology - Bangalore 26/C Electronics City Hosur Road Bangalore 560100 India Texas Advanced Computing Center University of Texas at Austin 10100 Burnet Road Austin TX 78758 United States Institute for Data Analysis and Visualization Department of Computer Science University of California Davis One Shields Avenue Davis CA 95616 United States

ISBN: (纸本)9789898565020

Grid-based computational simulations often use hybrid unstructured grids consisting of various types of elements. Most commonly used elements are tetrahedral, pentahedral (namely, square pyramids and right triangular prisms) and hexahedral elements. Extracting isosurfaces of scalar fields defined on such hybrid unstructured grids is often done using indirect methods, such as, (a) subdividing all non-tetrahedral cells into tetrahedra and computing the triangulated isosurfaces using the marching tetrahedra algorithm, or (b) triangulating intersection points of edges of cells and computing the isosurface using a standard triangulation algorithm. Using the basic ideas underlying the well-established marching cubes and marching tetrahedra algorithms, which are applied to hexahedral and tetrahedral elements, respectively, we generate look-up tables for extracting isosurfaces directly from pentahedral elements. By using appropriate look-up tables, it is possible to process nearly all types of hybrid unstructured grids used in practical applications without the need for indirect methods. We construct look-up tables for square pyramidal and triangular prismatic cells with accurate topological considerations.

关键词： Table lookup

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Progressive parallel coordinates

Progressive parallel coordinates

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Pacific (formerly Asia-Pacific APVIS) visualization Symposium

作者： René Rosenbaum Jian Zhi Bernd Hamann Visual Computing and Computer Graphics group (VCG) Institute for Computer Science University of Rostock Rostock Germany Institute for Data Analysis and Visualization (IDAV) Department of Computer Science University of California Davis CA USA Department of Industrial Engineering and Operations Research Columbia University NY USA

Progressive refinement is a methodology that makes it possible to elegantly integrate scalable data compression, access, and presentation into one approach. Specifically, this paper concerns the effective use of progressive parallel coordinates (PPCs), utilized routinely for high-dimensional data visualization. It discusses how the power of the typical stages of progressive data visualization can also be utilized fully for PPCs. Further, different implementations of the underlying methods and potential application domains are described. The paper also presents empirical results concerning the benefits of PPC with regard to efficient data management and improved presentation, indicating that the proposed approach is able to close the gap between data handling and visualization.

关键词： Lead visualization Logic gates

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Anisotropic range image integration

Anisotropic range image integration

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Joint 34th Symposium of the German Association for Pattern Recognition, DAGM 2012 and 36th Symposium of the Austrian Association for Pattern Recognition, OAGM 2012

作者： Schroers, Christopher Zimmer, Henning Valgaerts, Levi Bruhn, Andrés Demetz, Oliver Weickert, Joachim Mathematical Image Analysis Group Faculty of Mathematics and Computer Science Saarland University Saarbrücken 66041 Germany Computer Graphics Laboratory Department of Computer Science ETH Zurich Zurich 8092 Switzerland Max-Planck-Institut für Informatik Campus E1.4 Saarbrücken 66123 Germany Institute for Visualization and Interactive Systems University of Stuttgart Universitätsstraße 38 70569 Stuttgart Germany

ISBN: (纸本)9783642327162

Obtaining high-quality 3D models of real world objects is an important task in computer vision. A very promising approach to achieve this is given by variational range image integration methods: They are able to deal with a substantial amount of noise and outliers, while regularising and thus creating smooth surfaces at the same time. Our paper extends the state-of-the-art approach of Zach et al.(2007) in several ways: (i) We replace the isotropic space-variant smoothing behaviour by an anisotropic (direction-dependent) one. Due to the directional adaptation, a better control of the smoothing with respect to the local structure of the signed distance field can be achieved. (ii) In order to keep data and smoothness term in balance, a normalisation factor is introduced. As a result, oversmoothing of locations that are seen seldom is prevented. This allows high quality reconstructions in uncontrolled capture setups, where the camera positions are unevenly distributed around an object. (iii) Finally, we use the more accurate closest signed distances instead of directional signed distances when converting range images into 3D signed distance fields. Experiments demonstrate that each of our three contributions leads to clearly visible improvements in the reconstruction quality. © 2012 Springer-Verlag.

关键词： computer vision

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Structural and magnetic properties in the quantum S=12 dimer system Ba3(Cr1−xVx)2O8 with site disorder

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Physical Review B 2013年第14期87卷 144427-144427页

作者： Tao Hong L. Y. Zhu X. Ke V. O. Garlea Y. Qiu Y. Nambu H. Yoshizawa M. Zhu G. E. Granroth A. T. Savici Zheng Gai H. D. Zhou Quantum Condensed Matter Division Oak Ridge National Laboratory Oak Ridge Tennessee 37831-6393 USA Materials Science Division Argonne National Laboratory Argonne Illinois 60439 USA Department of Physics and Astronomy Michigan State University East Lansing Michigan 48824 USA Center for Neutron Research National Institute of Standards and Technology Gaithersburg Maryland 20899 USA Department of Materials and Engineering University of Maryland College Park Maryland 20742 USA Institute of Multidisciplinary Research for Advanced Materials Tohoku University 2-1-1 Katahira Sendai 980-8577 Japan Neutron Science Laboratory Institute for Solid State Physics University of Tokyo 106-1 Shirakata Tokai Ibaraki 319-1106 Japan Neutron Data Analysis and Visualization Division Oak Ridge National Laboratory Oak Ridge Tennessee 37831-6393 USA Center for Nanophase Materials Sciences Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA National High Magnetic Field Laboratory Florida State University Tallahassee Florida 32306-4005 USA Department of Physics and Astronomy University of Tennessee Knoxville Tennessee 37996-1200 USA

We report a comprehensive study of dc susceptibility, specific-heat, neutron-diffraction, and inelastic neutron-scattering measurements on polycrystalline Ba3(Cr1−xVx)2O8 samples, where x=0, 0.06, 0.15, and 0.53. A Jahn-Teller structure transition occurs for x=0, 0.06, and 0.15 samples, and the transition temperature is reduced upon vanadium substitution from 70(2) K at x=0 to 60(2) K at x=0.06 and 0.15. The structure becomes less distorted as x increases, and such transition disappears at x=0.53. The observed magnetic excitation spectrum indicates that the singlet ground state remains unaltered and spin-gap energy Δ=1.3(1) meV is identical within the instrument resolution for all x. In addition, the dispersion bandwidth W decreases with increase of x. At x=0.53, W is reduced to 1.4(1) meV from 2.0(1) meV at x=0.

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