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Item Toward Wall Function Consistent Interpolation of Flow Fields(The Eurographics Association, 2013) Üffinger, Markus; Sadlo, Filip; Munz, Claus-Dieter; Ertl, Thomas; Mario Hlawitschka and Tino WeinkaufIn this paper we provide a first step toward simulation-consistent visualization techniques. We focus on wall functions modeling near-wall flow in computational fluid dynamics (CFD) using the law of the wall. By integrating these functions, which are effective only in cells adjacent to solid boundaries, with traditional interpolation schemes used in the interior of the domain, we obtain results that account for the simulation model. We demonstrate the advantages of our scheme using flow visualization techniques on two three-dimensional CFD examples.Item Visual Analytics of Microblog Data for Public Behavior Analysis in Disaster Events(The Eurographics Association, 2013) Chae, Junghoon; Thom, Dennis; Jang, Yun; Kim, Sung Ye; Ertl, Thomas; Ebert, David S.; M. Pohl and H. SchumannIn disaster management, analysis of public behavior plays an important role for evacuation planning. Unfortunately, finding meaningful information for analysis is challenging and collecting relevant data can be very costly. However, the growing dataset of Location-based Social Networks services with its time-stamped, geo-located data offers a new opportunity. Such spatiotemporal data has substantial potential to increase the situational awareness of local events and provide for both planning and investigation. In this paper, we present a visual analytics tool that provides users with interactive social media data analysis and investigation in order to help evacuation planning, analysis, and response. We demonstrate how to improve investigation by analyzing the extracted public behavior responses before and after the evacuation order during the natural disaster event, such as Hurricane Sandy.Item Atomistic Visualization of Mesoscopic Whole-Cell Simulations Using Ray-Casted Instancing(The Eurographics Association and Blackwell Publishing Ltd., 2013) Falk, Martin; Krone, Michael; Ertl, Thomas; Holly Rushmeier and Oliver DeussenMolecular visualization is an important tool for analysing the results of biochemical simulations. With modern GPU ray casting approaches, it is only possible to render several million of atoms interactively unless advanced acceleration methods are employed. Whole‐cell simulations consist of at least several billion atoms even for simplified cell models. However, many instances of only a few different proteins occur in the intracellular environment, which can be exploited to fit the data into the graphics memory. For each protein species, one model is stored and rendered once per instance. The proposed method exploits recent algorithmic advances for particle rendering and the repetitive nature of intracellular proteins to visualize dynamic results from mesoscopic simulations of cellular transport processes. We present two out‐of‐core optimizations for the interactive visualization of data sets composed of billions of atoms as well as details on the data preparation and the employed rendering techniques. Furthermore, we apply advanced shading methods to improve the image quality including methods to enhance depth and shape perception besides non‐photorealistic rendering methods. We also show that the method can be used to render scenes that are composed of triangulated instances, not only implicit surfaces.Molecular visualization is an important tool for analyzing the results of biochemical simulations. With modern GPU ray casting approaches it is only possible to render several million of atoms interactively unless advanced acceleration methods are employed. Whole‐cell simulations consist of at least several billion atoms even for simplified cell models. However, many instances of only a few different proteins occur in the intracellular environment, which can be exploited to fit the data into the graphics memory. For each protein species, one model is stored and rendered once per instance. The proposed method exploits recent algorithmic advances for particle rendering and the repetitive nature of intracellular proteins to visualize dynamic results from mesoscopic simulations of cellular transport processes with implicit surfaces and triangular meshes.Item Interactive Extraction and Tracking of Biomolecular Surfaces Features(The Eurographics Association and Blackwell Publishing Ltd., 2013) Krone, Michael; Reina, Guido; Schulz, Christoph; Kulschewski, Tobias; Pleiss, Jürgen; Ertl, Thomas; B. Preim, P. Rheingans, and H. TheiselWe present a coordinated-view application for the analysis of molecular surface features like cavities, channels and pockets. Our tool employs object-space ambient occlusion for the detection of such features and tracks them over time. It offers time-dependent graphs of metrics concerning those features and allows analyzing the temporal relationship of the features, i.e. when they (dis)appear, split or merge and which features participate in each of these events. The automated analysis process is performed in real time while the user interactively explores a dynamic data set. The system supports linking and brushing to allow for a user-guided visual analysis based on different aspects of the data. We demonstrate the effectiveness of our approach by applying it to data sets from biochemistry and report the insights that can be gained. We also evaluate the benefits of our method with respect to recent advancements in the field. The algorithmic pipeline leverages the computing power of modern GPUs, thus achieving interactive frame rates without any precomputation for fully dynamic data sets.Item Local Extraction of Bifurcation Lines(The Eurographics Association, 2013) Machado, Gustavo M.; Sadlo, Filip; Ertl, Thomas; Michael Bronstein and Jean Favre and Kai HormannWe present local extraction of bifurcation lines together with extraction of their manifolds, a topological feature that has not yet been sufficiently recognized in scientific visualization. The bifurcation lines are extracted by a modification of the vortex core line extraction techniques due to Sujudi-Haimes, and Roth-Peikert, both formulated using the parallel vectors operator. While the former provides acceptable results only in configurations with high hyperbolicity and low curvature of the bifurcation lines, the latter operates only well in configurations with low hyperbolicity but is able to perform well with strong curvature of the bifurcation lines, however, with the drawback that it often fails to provide a solution. We present refinement of the solutions of the parallel vectors operator as a means to improve both criteria and, in particular, to refine the solutions of the Sujudi-Haimes criterion in cases where the Roth-Peikert criterion fails. We exemplify our technique on synthetic data, data from computational fluid dynamics, and on magnetohydrodynamics data. As a particularly interesting application, we demonstrate that our technique is able to extract saddle-type periodic orbits locally, and in case of high hyperbolicity at higher accuracy than traditional techniques based on integral curves.Item TrajectoryLenses - A Set-based Filtering and Exploration Technique for Long-term Trajectory Data(The Eurographics Association and Blackwell Publishing Ltd., 2013) Krüger, Robert; Thom, Dennis; Wörner, Michael; Bosch, Harald; Ertl, Thomas; B. Preim, P. Rheingans, and H. TheiselThe visual analysis of spatiotemporal movement is a challenging task. There may be millions of routes of different length and shape with different origin and destination, extending over a long time span. Furthermore there can be various correlated attributes depending on the data domain, e.g. engine measurements for mobility data or sensor data for animal tracking. Visualizing such data tends to produce cluttered and incomprehensible images that need to be accompanied by sophisticated filtering methods. We present TrajectoryLenses, an interaction technique that extends the exploration lens metaphor to support complex filter expressions and the analysis of long time periods. Analysts might be interested only in movements that occur in a given time range, traverse a certain region, or end at a given area of interest (AOI). Our lenses can be placed on an interactive map to identify such geospatial AOIs. They can be grouped with set operations to create powerful geospatial queries. For each group of lenses, users can access aggregated data for different attributes like the number of matching movements, covered time, or vehicle performance. We demonstrate the applicability of our technique on a large, real-world dataset of electric scooter tracks spanning a 2-year period.Item Rendering Molecular Surfaces using Order-Independent Transparency(The Eurographics Association, 2013) Kauker, Daniel; Krone, Michael; Panagiotidis, Alexandros; Reina, Guido; Ertl, Thomas; Fabio Marton and Kenneth MorelandIn this paper we present a technique for interactively rendering transparent molecular surfaces. We use Puxels, our implementation of per-pixel linked lists for order-independent transparency rendering. Furthermore, we evaluate the usage of per-pixel arrays as an alternative for this rendering technique. We describe our real-time rendering technique for transparent depiction of complex molecular surfaces like the Solvent Excluded Surface which is based on constructive solid geometry. Additionally, we explain further graphical operations and extensions possible with the Puxels approach. The evaluation benchmarks the performance of the presented methods and compares it to other methods.