TY - CONF
T1 - FAnToM - Lessons Learned from Design, Implementation, Administration, and Use of a Visualization System for Over 10 Years
Y1 - 2009
A1 - Gerik Scheuermann
A1 - Alexander Wiebel
A1 - Christoph Garth
A1 - Mario Hlawitschka
A1 - Thomas Wischgoll
AB - Scientific visualization has become a central tool in many research areas since it has been established as a research discipline in 1987 [2]. Naturally, this development resulted in software tools specifically tailored for the visualization task at hand. While many such tools exist, the design choices underlying them vary greatly. This abstract describes some aspects of the FAnToM1 visualization system that is being developed since 1999. Initially created to support research in topological methods for vector and tensor fields, the system quickly grew into a visualization platform for general flow visualization specialized to data represented on unstructured grids. From this origin, FAnToM derives advanced data structures for point location and interpolation over unstructured meshes, as well as fast integral curve capabilities. More recently, FAnToM has gradually been extended to serve a wider area of visualization applications, including medical and graph visualization. Throughout the development of FAnToM, close collaboration with application domain scientists has been a strong priority to facilitate the system s usefulness on state-of-the-art problems. The continuous development of this system over a period of ten years revealed a number of important aspects that are crucial for the usefulness of a visualization system. Furthermore, some design choices underlying FAnToM are uncommon among visualization systems in general. Here, it is our aim to discuss some aspects and design choices underlying the FAnToM system to illustrate some of its properties and differences from other visualization systems. During the discussion, we will point out some experiences and lessons learned in working with the system on modern visualization applications.
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TY - JOUR
T1 - The State of the Art in Flow Visualization: Structure-Based Techniques
JF - SimVis 2008
Y1 - 2008
A1 - Gerik Scheuermann
A1 - Tobias Salzbrunn
A1 - Heike Jaenicke
A1 - Thomas Wischgoll
AB - The analysis of morphometric data of the vasculature of any organ requires appropriate visualization methods to be applied due to the vast number of vessels that can be present in such data. In addition, the geometric properties of vessel segments, i.e. being rather long and thin, can make it difficult to judge on relative position, despite depth cues such as proper lighting and shading of the vessels. Virtual environments that provide true 3-D visualization of the data can help enhance the visual perception. Ideally, the system should be relatively cost-effective. Hence, this paper describes a Linux-based virtual environment that utilizes a 50 inch plasma screen as its main display. The overall cost of the entire system is less than $3,500 which is considerably less than other commercial systems. The system was successfully used for visualizing vascular data sets providing true three-dimensional perception of the morphometric data.
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TY - CHAP
T1 - 3D Loop Detection and Visualization in Vector Fields
Y1 - 2003
A1 - Gerik Scheuermann
A1 - Thomas Wischgoll
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TY - CHAP
T1 - Evolution of Topology in Axi-Symmetric and 3-D Viscous Flows
T2 - Numerical Simulations of Incompressible Flows
Y1 - 2003
A1 - Gerik Scheuermann
A1 - Wolfgang Kollmann
A1 - Xavier Tricoche
A1 - Thomas Wischgoll
AB - Topological methods are used to establish global and to extract local structure properties of vector fields in axi-symmetric and 3-d flows as function of time. The notion of topological skeleton is applied to the interpretation of vector fields generated numerically by the Navier-Stokes equations. The flows considered are swirling jets with super-critical swirl numbers that show low Reynolds number turbulence in the break-up region.
JA - Numerical Simulations of Incompressible Flows
PB - World Scientific
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TY - JOUR
T1 - Parallel Computation of the Topological Skeleton of Vector Fields
JF - High Performance Computing (HPC 2003) Symposium
Y1 - 2003
A1 - Gerik Scheuermann
A1 - Thomas Wischgoll
KW - 2D flow
KW - Linux cluster
KW - parallel
KW - streamline computation
KW - streamlines
KW - vector field
AB - Vector fields occur in many of the problems in science and engineering. In combustion processes, for instance, vector fields describe the flow of the gas. This process can be enhanced using vector field visualization techniques. Also, wind tunnel experiments can be analyzed. An example is the design of an air wing. The wing can be optimized to create a smoother flow around it. To analyze such kind of datasets topological methods that clearly show the whole structure of the vector field in one picture are a very good tool. During the last years, many extensions were proposed for this method. In addition to standard topological methods we also detect closed streamlines since they are a topological feature that completes the topological analysis. To accelerate the computation of such a topological analysis we developed a parallel method to reduce computational time. Therefore, we spread the computation of the separatrices of the topological skeleton to clients of a computer cluster. To test our implementation we use a numerical simulation of a swirling jet with an inflow into a steady medium. We built two different Linux clusters as parallel test systems where we check the performance increase when adding more processors to the cluster. We show that we have a very low parallel overhead due to the neglectable communication expense of our implementation.
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TY - CONF
T1 - Evolution of Topology in Axi-Symmetric and 3-D Viscous Flows
Y1 - 2002
A1 - Gerik Scheuermann
A1 - Wolfgang Kollmann
A1 - Xavier Tricoche
A1 - Thomas Wischgoll
AB - Topological methods are used to establish global and to extract local structure properties of vector fields in axi-symmetric and 3-d flows as function of time. The notion of topological skeleton is applied to the interpretation of vector fields generated numerically by the Navier-Stokes equations. The flows considered are swirling jets with super-critical swirl numbers that show low Reynolds number turbulence in the break-up region.
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TY - JOUR
T1 - Locating Closed Streamlines in 3D Vector Fields
JF - Joint Eurographics and IEEE TCVG Symposium on Data Visualization 2002
Y1 - 2002
A1 - Gerik Scheuermann
A1 - Thomas Wischgoll
AB - The analysis and visualization of flows is a central problem in visualization. Topology based methods have gained increasing interest in recent years. This article describes a method for the detection of closed streamlines in 3D flows. It is based on a special treatment of cases where a streamline reenters a cell to prevent infinite cycling during streamline calculation. The algorithm checks for possible exits of a loop of crossed faces and detects structurally stable closed streamlines. These global features are not detected by conventional topology and feature detection algorithms.
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TY - JOUR
T1 - Topology Tracking for the Visualization of Time-Dependent Two-Dimensional Flows
JF - Computer and Graphics
Y1 - 2002
A1 - Gerik Scheuermann
A1 - Xavier Tricoche
A1 - Hans Hagen
A1 - Thomas Wischgoll
AB - The paper presents a topology-based visualization method for time-dependent two-dimensional vector fields. A time interpolation enables the accurate tracking of critical points and closed orbits as well as the detection and identification of structural changes. This completely characterizes the topology of the unsteady flow. Bifurcation theory provides the theoretical framework. The results are conveyed by surfaces that separate subvolumes of uniform flow behavior in a three-dimensional space-time domain.
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TY - JOUR
T1 - Detection and Visualization of Planar Closed Streamlines
JF - IEEE Transactions on Visualization and Computer Graphics
Y1 - 2001
A1 - Gerik Scheuermann
A1 - Thomas Wischgoll
AB - The analysis and visualization of flows is a central problem in visualization. Topology based methods have gained increasing interest in recent years. This article describes a method for the detection of closed streamlines in flows. It is based on a special treatment of cases where a streamline reenters a cell to prevent infinite cycling during streamline calculation. The algorithm checks for possible exits of a loop of crossed edges and detects structurally stable closed streamlines. These global features are not detected by conventional topology and feature detection algorithms.
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TY - JOUR
T1 - Distributed Computation of Planar Closed Streamlines
JF - IEEE Transactions on Visualization and Computer Graphics
Y1 - 2001
A1 - Thomas Wischgoll
A1 - Gerik Scheuermann
A1 - Hans Hagen
AB - The analysis and visualization of flows is a central problem in visualization. Topology based methods have gained increasing interest in recent years. This article describes a method for the detection of closed streamlines in flows. It is based on a special treatment of cases where a streamline reenters a cell to prevent infinite cycling during streamline calculation. The algorithm checks for possible exits of a loop of crossed edges and detects structurally stable closed streamlines. These global features are not detected by conventional topology and feature detection algorithms.
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TY - JOUR
T1 - Parallel Detection of Closed Streamlines in Planar Flows
JF - International Conference on Visualization, Imaging, and Image Processing
Y1 - 2001
A1 - Gerik Scheuermann
A1 - Hans Hagen
A1 - Thomas Wischgoll
KW - 2D flow
KW - closed streamline
KW - limit cycle
KW - Linux cluster
KW - parallel
KW - streamline computation
KW - vector field
AB - Closed streamlines are an integral part of vector field topology, since they behave like sources respectively sinks but are often neither considered nor detected. If a streamline computation makes too many steps or takes too long, the computation is usually terminated without any answer on the final behavior of the streamline. We developed an algorithm that detects closed streamlines during the integration process. Since the detection of all closed streamlines in a vector field requires the computation of many streamlines we extend this algorithm to a parallel version to enhance computational speed. To test our implementation we use a numerical simulation of a swirling jet with an inflow into a steady medium. We built two different Linux clusters as parallel test systems where we check the performance increase when adding more processors to the cluster. We show that we have a very low parallel overhead due to the neglectable communication expense of our implementation.
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TY - JOUR
T1 - Tracking Closed Streamlines in Time-Dependent Planar Flows
JF - Vision, Modeling, and Visualization 2001
Y1 - 2001
A1 - Gerik Scheuermann
A1 - Hans Hagen
A1 - Thomas Wischgoll
AB - Closed streamlines are a missing part in most visualizations of vector field topology. In this paper, we propose a method which detects closed streamlines in a time-dependent two-dimensional flow and investigates the behavior of these closed streamlines over time. We search in all timesteps for closed streamlines and connect them to each other in temporal order to get a tube shaped visualization. As a starting point for our investigation we look for changes of the type of critical points that lead to the creation or vanishing of closed streamlines (Hopf bifurcation). We follow the resulting limit cycle over time. In addition, changes of the topological skeleton, built by critical points and separatrices, are considered which may start or terminate the life of a closed streamline.
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TY - JOUR
T1 - Visualization of Temporal Distances
JF - Late Breaking Hot Topics of IEEE Symposium on Visualization 1999
Y1 - 1999
A1 - Gerik Scheuermann
A1 - Hans Hagen
A1 - Thomas Wischgoll
KW - deformation
KW - Information Visualization
KW - physically based modeling
KW - transport system
AB - In order to visualize temporal distances, i.e. the time for traveling from one place to another, we arrange some selected cities according to these distances. In this way, the new positions reflect the connectivity of these cities with respect to time. Unlike existing approaches using tables, our method facilitates a global examination of the connectivity of a whole country. For the database, any connectivity information can be used as long as it is ensured that it is unambiguous. Therefore, any transport system can be considered and even a mixture of such systems could be visualized.
ER -