00465nas a2200121 4500008004100000245012400041210006900165100001700234700001600251700001700267700002200284856003700306 2007 eng d00aUsability of multiple degree-of-freedom input devices and virtual reality displays for interactive visual data analysis0 aUsability of multiple degreeoffreedom input devices and virtual 1 aMeyer, Joerg1 aHagen, Hans1 aMoritz, Elke1 aWischgoll, Thomas uhttp://www.knoesis.org/node/234900988nas a2200145 4500008004100000245008400041210006900125300001200194520051700206100002300723700002100746700001600767700002200783856003700805 2002 eng d00aTopology Tracking for the Visualization of Time-Dependent Two-Dimensional Flows0 aTopology Tracking for the Visualization of TimeDependent TwoDime a249-2583 aThe 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.
1 aScheuermann, Gerik1 aTricoche, Xavier1 aHagen, Hans1 aWischgoll, Thomas uhttp://www.knoesis.org/node/237901042nas a2200133 4500008004100000245005700041210005700098300006100155520059400216100002200810700002300832700001600855856003700871 2001 eng d00aDistributed Computation of Planar Closed Streamlines0 aDistributed Computation of Planar Closed Streamlines aIEEE Transactions on Visualization and Computer Graphics3 aThe 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.
1 aWischgoll, Thomas1 aScheuermann, Gerik1 aHagen, Hans uhttp://www.knoesis.org/node/238901604nas a2200217 4500008004100000245006100041210006100102300001000163520099000173653001201163653002201175653001601197653001801213653001301231653002701244653001701271100002301288700001601311700002201327856003701349 2001 eng d00aParallel Detection of Closed Streamlines in Planar Flows0 aParallel Detection of Closed Streamlines in Planar Flows a84-883 aClosed 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.
10a2D flow10aclosed streamline10alimit cycle10aLinux cluster10aparallel10astreamline computation10avector field1 aScheuermann, Gerik1 aHagen, Hans1 aWischgoll, Thomas uhttp://www.knoesis.org/node/239101207nas a2200133 4500008004100000245006300041210006200104300001200166520079700178100002300975700001600998700002201014856003701036 2001 eng d00aTracking Closed Streamlines in Time-Dependent Planar Flows0 aTracking Closed Streamlines in TimeDependent Planar Flows a447-4543 aClosed 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.
1 aScheuermann, Gerik1 aHagen, Hans1 aWischgoll, Thomas uhttp://www.knoesis.org/node/239001105nas a2200181 4500008004100000245004000041210004000081300001100121520059600132653001600728653003000744653003000774653002100804100002300825700001600848700002200864856003700886 1999 eng d00aVisualization of Temporal Distances0 aVisualization of Temporal Distances a 43-463 aIn 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.10adeformation10aInformation Visualization10aphysically based modeling10atransport system1 aScheuermann, Gerik1 aHagen, Hans1 aWischgoll, Thomas uhttp://www.knoesis.org/node/2282