![]() ![]() Automatic Stream Surface Seeding M. Edmunds, T. McLoughlin, R.S. Laramee, G. Chen, E. Zhang, N. Max. In EUROGRAPHICS 2011 Short Papers, pp. 53--56. 2011. |
![]() ![]() A wildland fire modeling and visualization environment, J. Mandel, J.D. Beezley, A. Kochanski, V.Y. Kondratenko, L. Zhang, E. Anderson, J. Daniels II, C.T. Silva, C.R. Johnson. In Proceedings of the Ninth Symposium on Fire and Forest Meteorology, pp. (published online). 2011. |
![]() ![]() Simple and Efficient Mesh Layout with Space-Filling Curves H.T. Vo, C.T. Silva, L.F. Scheidegger, V. Pascucci. In Journal of Graphics, GPU, and Game Tools, pp. 25--39. 2011. ISSN: 2151-237X |
![]() ![]() Branching and Circular Features in High Dimensional Data Bei Wang, B. Summa, V. Pascucci, M. Vejdemo-Johansson. In IEEE Transactions of Visualization and Computer Graphics (TVCG), Vol. 17, No. 12, pp. 1902--1911. 2011. DOI: 10.1109/TVCG.2011.177 PubMed ID: 22034307 Large observations and simulations in scientific research give rise to high-dimensional data sets that present many challenges and opportunities in data analysis and visualization. Researchers in application domains such as engineering, computational biology, climate study, imaging and motion capture are faced with the problem of how to discover compact representations of high dimensional data while preserving their intrinsic structure. In many applications, the original data is projected onto low-dimensional space via dimensionality reduction techniques prior to modeling. One problem with this approach is that the projection step in the process can fail to preserve structure in the data that is only apparent in high dimensions. Conversely, such techniques may create structural illusions in the projection, implying structure not present in the original high-dimensional data. Our solution is to utilize topological techniques to recover important structures in high-dimensional data that contains non-trivial topology. Specifically, we are interested in high-dimensional branching structures. We construct local circle-valued coordinate functions to represent such features. Subsequently, we perform dimensionality reduction on the data while ensuring such structures are visually preserved. Additionally, we study the effects of global circular structures on visualizations. Our results reveal never-before-seen structures on real-world data sets from a variety of applications. Keywords: Dimensionality reduction, circular coordinates, visualization, topological analysis |
![]() ![]() Combinatorial Laplacian Image Cloning A. Cuadros-Vargas, L.G. Nonato, V. Pascucci. In Proceedings of XXIV Sibgrapi – Conference on Graphics, Patterns and Images, pp. 236--241. 2011. DOI: 10.1109/SIBGRAPI.2011.7 Seamless image cloning has become one of the most important editing operation for photomontage. Recent coordinate-based methods have lessened considerably the computational cost of image cloning, thus enabling interactive applications. However, those techniques still bear severe limitations as to concavities and dynamic shape deformation. In this paper we present novel methodology for image cloning that turns out to be highly efficient in terms of computational times while still being more flexible than existing techniques. Our approach builds on combinatorial Laplacian and fast Cholesky factorization to ensure interactive image manipulation, handling holes, concavities, and dynamic deformations during the cloning process. The provided experimental results show that the proposed technique outperforms existing methods in requisites such as accuracy and flexibility. |
![]() ![]() Experiences in Disseminating Educational Visualizations N. Andrysco, P. Rosen, V. Popescu, B. Benes, K.R. Gurney. In Lecture Notes in Computer Science (7th International Symposium on Visual Computing), Vol. 2, pp. 239--248. September, 2011. DOI: 10.1007/978-3-642-24031-7_24 Most visualizations produced in academia or industry have a specific niche audience that is well versed in either the often complicated visualization methods or the scientific domain of the data. Sometimes it is useful to produce visualizations that can communicate results to a broad audience that will not have the domain specific knowledge often needed to understand the results. In this work, we present our experiences in disseminating the results of two studies to national audience. The resulting visualizations and press releases allowed the studies’ researchers to educate a national, if not global, audience. |
![]() ![]() An Evaluation of 3-D Scene Exploration Using a Multiperspective Image Framework P. Rosen, V. Popescu. In The Visual Computer, Vol. 27, No. 6-8, Springer-Verlag New York, Inc., pp. 623--632. 2011. DOI: 10.1007/s00371-011-0599-2 PubMed ID: 22661796 PubMed Central ID: PMC3364594 Multiperspective images (MPIs) show more than what is visible from a single viewpoint and are a promising approach for alleviating the problem of occlusions. We present a comprehensive user study that investigates the effectiveness of MPIs for 3-D scene exploration. A total of 47 subjects performed searching, counting, and spatial orientation tasks using both conventional and multiperspective images. We use a flexible MPI framework that allows trading off disocclusion power for image simplicity. The framework also allows rendering MPI images at interactive rates, which enables investigating interactive navigation and dynamic 3-D scenes. The results of our experiments show that MPIs can greatly outperform conventional images. For searching, subjects performed on average 28% faster using an MPI. For counting, accuracy was on average 91% using MPIs as compared to 42% for conventional images. Keywords: Interactive 3-D scene exploration, Navigation, Occlusions, User study, Visual interfaces |
![]() ![]() A User Study of Visualization Effectiveness Using EEG and Cognitive Load E.W. Anderson, K.C. Potter, L.E. Matzen, J.F. Shepherd, G.A. Preston, C.T. Silva. In Computer Graphics Forum, Vol. 30, No. 3, Note: Awarded 2nd Best Paper!, Edited by H. Hauser and H. Pfister and J.J. van Wijk, pp. 791--800. June, 2011. DOI: 10.1111/j.1467-8659.2011.01928.x Effectively evaluating visualization techniques is a difficult task often assessed through feedback from user studies and expert evaluations. This work presents an alternative approach to visualization evaluation in which brain activity is passively recorded using electroencephalography (EEG). These measurements are used to compare different visualization techniques in terms of the burden they place on a viewer's cognitive resources. In this paper, EEG signals and response times are recorded while users interpret different representations of data distributions. This information is processed to provide insight into the cognitive load imposed on the viewer. This paper describes the design of the user study performed, the extraction of cognitive load measures from EEG data, and how those measures are used to quantitatively evaluate the effectiveness of visualizations. |
![]() ![]() Branching and Circular Features in High Dimensional Data SCI Technical Report, Bei Wang, B. Summa, V. Pascucci, M. Vejdemo-Johansson. No. UUSCI-2011-005, SCI Institute, University of Utah, 2011. |
![]() Topological Methods in Data Analysis and Visualization: Theory, Algorithms, and Applications (Mathematics and Visualization), Valerio Pascucci, Xavier Tricoche, Hans Hagen, Julien Tierny. Springer, 2011. ISBN: 978-3642150135 |
![]() ![]() Non-Pinhole Approximations for Interactive Rendering P. Rosen, V. Popescu, K. Hayward, C. Wyman. In IEEE Computer Graphics and Applications, Vol. 99, 2011. |
![]() ![]() Edge Maps: Representing Flow with Bounded Error H. Bhatia, S. Jadhav, P.-T. Bremer, G. Chen, J.A. Levine, L.G. Nonato, V. Pascucci. In Proceedings of IEEE Pacific Visualization Symposium 2011, Hong Kong, China, Note: Won Best Paper Award!, pp. 75--82. March, 2011. DOI: 10.1109/PACIFICVIS.2011.5742375 |
![]() ![]() Visual Links across Applications M. Waldner, W. Puff, A. Lex, M. Streit, D. Schmalstieg. In Proceedings of the Conference on Graphics Interface (GI '10), Canadian Human-Computer Communications Society, pp. 129--136. 2010. ISBN: 1568817125 The tasks carried out by modern information workers become increasingly complex and time-consuming. They often require to evaluate, interpret, and compare information from different sources presented in multiple application windows. With large, high resolution displays, multiple application windows can be arranged in a way so that a large amount of information is visible simultaneously. However, individual application windows' contents and visual representations are isolated and relations between information items contained in these windows are not explicit. Thus, relating and comparing information across applications has to be executed manually by the user, which is a tedious and error-prone task. |
![]() ![]() Caleydo: Design and Evaluation of a Visual Analysis Framework for Gene Expression Data in its Biological Context A. Lex, M. Streit, E. Kruijff, D. Schmalstieg. In Proceeding of the IEEE Symposium on Pacific Visualization (PacificVis '10), pp. 57--64. 2010. ISBN: 424466856 DOI: 10.1109/PACIFICVIS.2010.5429609 The goal of our work is to support experts in the process of hypotheses generation concerning the roles of genes in diseases. For a deeper understanding of the complex interdependencies between genes, it is important to bring gene expressions (measurements) into context with pathways. Pathways, which are models of biological processes, are available in online databases. In these databases, large networks are decomposed into small sub-graphs for better manageability. This simplification results in a loss of context, as pathways are interconnected and genes can occur in multiple instances scattered over the network. Our main goal is therefore to present all relevant information, i.e., gene expressions, the relations between expression and pathways and between multiple pathways in a simple, yet effective way. To achieve this we employ two different multiple-view approaches. Traditional multiple views are used for large datasets or highly interactive visualizations, while a 2.5D technique is employed to support a seamless navigation of multiple pathways which simultaneously links to the expression of the contained genes. This approach facilitates the understanding of the interconnection of pathways, and enables a non-distracting relation to gene expression data. We evaluated Caleydo with a group of users from the life science community. Users were asked to perform three tasks: pathway exploration, gene expression analysis and information comparison with and without visual links, which had to be conducted in four different conditions. Evaluation results show that the system can improve the process of understanding the complex network of pathways and the individual effects of gene expression regulation considerably. Especially the quality of the available contextual information and the spatial organization was rated good for the presented 2.5D setup. |
![]() ![]() Pathline: A Tool for Comparative Functional Genomics M.D. Meyer, B. Wong, M. Styczynski, T. Munzner, H. Pfister. In Computer Graphics Forum, Vol. 29, No. 3, Wiley-Blackwell, pp. 1043--1052. Aug, 2010. DOI: 10.1111/j.1467-8659.2009.01710.x Biologists pioneering the new field of comparative functional genomics attempt to infer the mechanisms of gene regulation by looking for similarities and differences of gene activity over time across multiple species. They use three kinds of data: functional data such as gene activity measurements, pathway data that represent a series of reactions within a cellular process, and phylogenetic relationship data that describe the relatedness of species. No existing visualization tool can visually encode the biologically interesting relationships between multiple pathways, multiple genes, and multiple species. We tackle the challenge of visualizing all aspects of this comparative functional genomics dataset with a new interactive tool called Pathline. In addition to the overall characterization of the problem and design of Pathline, our contributions include two new visual encoding techniques. One is a new method for linearizing metabolic pathways that provides appropriate topological information and supports the comparison of quantitative data along the pathway. The second is the curvemap view, a depiction of time series data for comparison of gene activity and metabolite levels across multiple species. Pathline was developed in close collaboration with a team of genomic scientists. We validate our approach with case studies of the biologists' use of Pathline and report on how they use the tool to confirm existing findings and to discover new scientific insights. |