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Item Toward a Lagrangian Vector Field Topology(The Eurographics Association and Blackwell Publishing Ltd., 2010) Fuchs, Raphael; Peikert, Ronny; Kemmler, Jan; Schindler, Benjamin; Waser, Juergen; Sadlo, Filip; Hauser, Helwig; G. Melancon, T. Munzner, and D. WeiskopfIn this paper we present an extended critical point concept which allows us to apply vector field topology in the case of unsteady flow.We propose a measure for unsteadiness which describes the rate of change of the velocities in a fluid element over time. This measure allows us to select particles for which topological properties remain intact inside a finite spatio-temporal neighborhood. One benefit of this approach is that the classification of critical points based on the eigenvalues of the Jacobian remains meaningful. In the steady case the proposed criterion reduces to the classical definition of critical points. As a first step we show that finding an optimal Galilean frame of reference can be obtained implicitly by analyzing the acceleration field. In a second step we show that this can be extended by switching to the Lagrangian frame of reference. This way the criterion can detect critical points moving along intricate trajectories. We analyze the behavior of the proposed criterion based on two analytical vector fields for which a correct solution is defined by their inherent symmetries and present results for numerical vector fields.Item Interactive Visual Analysis of Families of Surfaces: An Application to Car Race and Car Setup(The Eurographics Association, 2010) Matkovic, Kresimir; Gracanin, Denis; Splechtna, Reiner; Hauser, Helwig; Joern Kohlhammer and Daniel KeimModern simulations often produce time series, or even functions of two variables as outputs for single attributes. Such complex data require carefully chosen and designed analysis procedures and the corresponding data model. The use of previously developed curve and surface views provides strong support for visual exploration and analysis of complex data. In this paper we describe how interactive visual analysis can support users in getting insight into complex data. The case study, based on TORCS 3D racing cars simulator, illustrates our approach and its successful application to a real world problem. The analysis of the car parameters and driving performances during races provides an insight and explanation for race results. That insight is then used to fine-tune car parameters to achieve better driving performance.Item Brushing Moments in Interactive Visual Analysis(The Eurographics Association and Blackwell Publishing Ltd., 2010) Kehrer, Johannes; Filzmoser, Peter; Hauser, Helwig; G. Melancon, T. Munzner, and D. WeiskopfWe present a systematic study of opportunities for the interactive visual analysis of multi-dimensional scientific data that is based on the integration of statistical aggregations along selected independent data dimensions in a framework of coordinated multiple views (with linking and brushing). Traditional and robust estimates of the four statistical moments (mean, variance, skewness, and kurtosis) as well as measures of outlyingness are integrated in an iterative visual analysis process. Brushing particular statistics, the analyst can investigate data characteristics such as trends and outliers. We present a categorization of beneficial combinations of attributes in 2D scatterplots: (a) kth vs. (k+1)th statistical moment of a traditional or robust estimate, (b) traditional vs. robust version of the same moment, (c) two different robust estimates of the same moment. We propose selected view transformations to iteratively construct this multitude of informative views as well as to enhance the depiction of the statistical properties in scatterplots and quantile plots. In the framework, we interrelate the original distributional data and the aggregated statistics, which allows the analyst to work with both data representations simultaneously. We demonstrate our approach in the context of two visual analysis scenarios of multi-run climate simulations.Item Editorial(The Eurographics Association, 2010) Hauser, Helwig; Reinhard, Erik; Helwig Hauser and Erik ReinhardThe annual EUROGRAPHICS conference includes several very interesting tracks, of which the State-of-the-Art Reports (STARs) has proved to be consistently popular. The reports in this track survey topic areas that have not been covered before, at least not recently, and allow interested readers to quickly gain an overview as well as a first understanding of the related research in the covered areas.Item Guided Visualization of Ultrasound Image Sequences(The Eurographics Association, 2010) Angelelli, Paolo; Viola, Ivan; Nylund, Kim; Gilja, Odd Helge; Hauser, Helwig; Dirk Bartz and Charl Botha and Joachim Hornegger and Raghu Machiraju and Alexander Wiebel and Bernhard PreimUltrasonography allows informative and expressive real time examinations of patients. Findings are usually reported as printouts, screen shots and video sequences. However, in certain scenarios, the amount of imaged ultrasound data is considerable or it is challenging to detect the anatomical features of interest. Post-examination access to the information present in the data is, therefore, cumbersome. The examiner must, in fact, review entire video sequences or risk to lose relevant information by reducing the examination to single screen shot and printouts. In this paper we propose a novel post-processing pipeline for guided visual exploration of ultrasound video sequences, to allow easier and richer exploration and analysis of the data. We demonstrate the usefulness of this approach by applying it to a liver examination case, showing easier and quicker ultrasound image selection and data exploration.Item Visual Analysis of Multivariate Movement Data using Interactive Difference Views(The Eurographics Association, 2010) Lampe, Ove Daae; Kehrer, Johannes; Hauser, Helwig; Reinhard Koch and Andreas Kolb and Christof Rezk-SalamaMovement data consisting of a large number of spatio-temporal agent trajectories is challenging to visualize, especially when all trajectories are attributed with multiple variates. In this paper, we demonstrate the visual exploration of such movement data through the concept of interactive difference views. By reconfiguring the difference views in a fast and flexible way, we enable temporal trend discovery. We are able to analyze large amounts of such movement data through the use of a frequency-based visualization based on kernel density estimates (KDE), where it is also possible to quantify differences in terms of the units of the visualized data. Using the proposed techniques, we show how the user can produce quantifiable movement differences and compare different categorical attributes (such as weekdays, ship-type, or the general wind direction), or a range of a quantitative attribute (such as how two hours' traffic compares to the average). We present results from the exploration of vessel movement data from the Norwegian Coastal Administration, collected by the Automatic Identification System (AIS) coastal tracking. There are many interacting patterns in such movement data, both temporal and other more intricate, such as weather conditions, wave heights, or sunlight. In this work we study these movement patterns, answering specific questions posed by Norwegian Coastal Administration on potential shipping lane optimizations.