TY - GEN A1 - Rosanwo, Olufemi A1 - Petz, Christoph A1 - Prohaska, Steffen A1 - Hotz, Ingrid A1 - Hege, Hans-Christian T1 - Dual Streamline Seeding - Method and Implementation N2 - This work introduces a novel streamline seeding technique based on dual streamlines that are orthogonal to the vector field, instead of tangential. The greedy algorithm presented here produces a net of orthogonal streamlines that is iteratively refined resulting in good domain coverage and a high degree of continuity and uniformity. The algorithm is easy to implement and efficient, and it naturally extends to curved surfaces. N2 - In dieser Arbeit wird eine neue Strategie zur Platzierung von Stromlinien vorgestellt. Hierzu werden zusätzliche duale Stromlinien verwendet, die --im Gegensatz zur üblichen Definition-- orthogonal zum Vektorfeld verlaufen. Der vorgestellte Greedy-Algorithmus berechnet ein Netz aus orthogonalen Stromlinien, welches iterativ verfeinert wird, was zu einer guten Abdeckung der Domäne und einer gleichmäßigen Verteilung der Stromlinien führt. Es handelt sich um einen einfach zu implementierenden und effizienten Algorithmus, der direkt auf gekrümmten Oberflächen anwendbar ist. T3 - ZIB-Report - 08-49 Y1 - 2008 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-11032 SN - 1438-0064 ER - TY - GEN A1 - Kratz, Andrea A1 - Meyer, Björn A1 - Hotz, Ingrid T1 - A Visual Approach to Analysis of Stress Tensor Fields N2 - We present a visual approach for the exploration of stress tensor fields. Therefore, we introduce the idea of multiple linked views to tensor visualization. In contrast to common tensor visualization methods that only provide a single view to the tensor field, we pursue the idea of providing various perspectives onto the data in attribute and object space. Especially in the context of stress tensors, advanced tensor visualization methods have a young tradition. Thus, we propose a combination of visualization techniques domain experts are used to with statistical views of tensor attributes. The application of this concept to tensor fields was achieved by extending the notion of shape space. It provides an intuitive way of finding tensor invariants that represent relevant physical properties. Using brushing techniques, the user can select features in attribute space, which are mapped to displayable entities in a three-dimensional hybrid visualization in object space. Volume rendering serves as context, while glyphs encode the whole tensor information in focus regions. Tensorlines can be included to emphasize directionally coherent features in the tensor field. We show that the benefit of such a multi-perspective approach is manifold. Foremost, it provides easy access to the complexity of tensor data. Moreover, including wellknown analysis tools, such as Mohr diagrams, users can familiarize themselves gradually with novel visualization methods. Finally, by employing a focus-driven hybrid rendering, we significantly reduce clutter, which was a major problem of other three-dimensional tensor visualization methods. T3 - ZIB-Report - 10-26 KW - Visualisierung KW - Datenanalyse KW - Tensorfelder Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-11915 ER - TY - GEN A1 - Reininghaus, Jan A1 - Kasten, Jens A1 - Weinkauf, Tino A1 - Hotz, Ingrid T1 - Combinatorial Feature Flow Fields: Tracking Critical Points in Discrete Scalar Fields N2 - We propose a combinatorial algorithm to track critical points of 2D time-dependent scalar fields. Existing tracking algorithms such as Feature Flow Fields apply numerical schemes utilizing derivatives of the data, which makes them prone to noise and involve a large number of computational parameters. In contrast, our method is robust against noise since it does not require derivatives, interpolation, and numerical integration. Furthermore, we propose an importance measure that combines the spatial persistence of a critical point with its temporal evolution. This leads to a time-aware feature hierarchy, which allows us to discriminate important from spurious features. Our method requires only a single, easy-to-tune computational parameter and is naturally formulated in an out-of-core fashion, which enables the analysis of large data sets. We apply our method to a number of data sets and compare it to the stabilized continuous Feature Flow Field tracking algorithm. T3 - ZIB-Report - 11-02 KW - data analysis KW - feature detection KW - time-varying data KW - topology-based techniques Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-12151 ER - TY - GEN A1 - Kratz, Andrea A1 - Reininghaus, Jan A1 - Hadwiger, Markus A1 - Hotz, Ingrid T1 - Adaptive Screen-Space Sampling for Volume Ray-Casting N2 - This work is concerned with adaptive screen-space sampling for volume ray-casting. The goal is to reduce the number of rays being cast into the scene and, thus, the overall number of sampling points. We guarantee reliable images through explicit error control using an error estimator that is founded in the field of finite element methods (FEM). FEM theory further provides a well-founded theory to prove the efficiency of the presented algorithm via convergence analysis. We, therefore, compare the convergence behavior of our method against uniform subdivisions and a refinement scheme that was presented in the context of CPU volume ray-casting. Minimizing the number of sampling points is of interest for rendering large datasets where each evaluation might need an expensive decompression. Furthermore, with increasing screen resolutions high-resolution images are created more efficiently with our method. T3 - ZIB-Report - 11-04 Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-12446 ER - TY - CHAP A1 - Hlawitschka, Mario A1 - Hotz, Ingrid A1 - Kratz, Andrea A1 - Marai, G. Elisabeta A1 - Moreno, Rodrigo A1 - Scheuermann, Gerik A1 - Stommel, Markus A1 - Wiebel, Alexander A1 - Zhang, Eugene ED - Westin, Carl-Frederic ED - Burgeth, Bernhard ED - Vilanova, Anna T1 - Top Challenges in the Visualization of Engineering Tensor Fields T2 - Visualization and Processing of Tensors and Higher-Order Descriptors for Multi-Field Data Y1 - 2014 SP - 3 EP - 15 PB - Springer ER - TY - GEN A1 - Reininghaus, Jan A1 - Günther, David A1 - Hotz, Ingrid A1 - Weinkauf, Tino A1 - Seidel, Hans Peter T1 - Combinatorial Gradient Fields for 2D Images with Empirically Convergent Separatrices Y1 - 2012 UR - http://arxiv.org/abs/1208.6523 ER - TY - CHAP A1 - Kasten, Jens A1 - Zoufahl, Andre A1 - Hege, Hans-Christian A1 - Hotz, Ingrid T1 - Analysis of Vortex Merge Graphs T2 - VMV 2012: Vision, Modeling and Visualization Y1 - 2012 U6 - https://doi.org/10.2312/PE/VMV/VMV12/111-118 SP - 111 EP - 118 PB - Eurographics Association ER - TY - JOUR A1 - Günther, David A1 - Reininghaus, Jan A1 - Wagner, Hubert A1 - Hotz, Ingrid T1 - Efficient Computation of 3D Morse-Smale Complexes and Persistent Homology using Discrete Morse Theory JF - The Visual Computer Y1 - 2012 U6 - https://doi.org/10.1007/s00371-012-0726-8 VL - 28 IS - 10 SP - 959 EP - 969 ER - TY - CHAP A1 - Kasten, Jens A1 - Hotz, Ingrid A1 - Noack, Bernd A1 - Hege, Hans-Christian T1 - Vortex Merge Graphs in Two-dimensional Unsteady Flow Fields T2 - EuroVis – Short Papers Y1 - 2012 UR - http://diglib.eg.org/EG/DL/PE/EuroVisShort/EuroVisShort2012/001-005.pdf U6 - https://doi.org/10.2312/PE/EuroVisShort/EuroVisShort2012/001-005 SP - 1 EP - 5 PB - Eurographics Association CY - Vienna, Austria ER - TY - GEN A1 - Reininghaus, Jan A1 - Hotz, Ingrid ED - Peikert, Ronald ED - Carr, Hamish ED - Hauser, Helwig T1 - Computational Discrete Morse Theory for Divergence-Free 2D Vector Fields T2 - Topological Methods in Data Analysis and Visualization. Theory, Algorithms, and Applications. (TopoInVis 2011) Y1 - 2012 SP - 3 EP - 14 PB - Springer ER -