10 results
Search Results
Now showing 1 - 10 of 10
Item Interactive High-Quality Volume Rendering with Flexible Consumer Graphics Hardware(Eurographics Association, 2002) Engel, Klaus; Ertl, ThomasRecently, the classic rendering pipeline in 3D graphics hardware has become flexible by means of programmable geometry engines and rasterization units. This development is primarily driven by the mass market of computer games and entertainment software, whose demand for new special effects and more realistic 3D environments induced a reconsideration of the once static rendering pipeline. Besides the impact on visual scene complexity in computer games, these advances in flexibility provide an enormous potential for new volume rendering algorithms. Thereby, they make yet unseen quality as well as improved performance for scientific visualization possible and allow to visualize hidden features contained within volumetric data. The goal of this report is to deliver insight into the new possibilities that programmable state-of-the-art graphics hardware offers to the field of interactive, high-quality volume rendering. We cover different slicing approaches for texture-based volume rendering, non-polygonal iso-surfaces, dot-product shading, environment-map shading, shadows, pre- and post-classification, multi-dimensional classification, high-quality filtering, pre-integrated classification and pre-integrated volume rendering, large volume visualization and volumetric effects.Item Interactive Visualization with Programmable Graphics Hardware(Eurographics Association, 2002) Ertl, ThomasOne of the main scientific goals of visualization is the development of algorithms and appropriate data models which facilitate interactive visual analysis and direct manipulation of the increasingly large data sets which result from simulations running on massive parallel computer systems, from measurements employing fast highresolution sensors, or from large databases and hierarchical information spaces. This task can only be achieved with the optimization of all stages of the visualization pipeline: filtering, compression, and feature extraction of the raw data sets, adaptive visualization mappings which allow the users to choose between speed and accuracy, and exploiting new graphics hardware features for fast and high-quality rendering. The recent introduction of advanced programmability in widely available graphics hardware has already led to impressive progress in the area of volume visualization. However, besides the acceleration of the final rendering, flexible graphics hardware is increasingly being used also for the mapping and filtering stages of the visualization pipeline, thus giving rise to new levels of interactivity in visualization applications. The talk will present recent results of applying programmable graphics hardware in various visualization algorithms covering volume data, flow data, terrains, NPR rendering, and distributed and remote applications.Item Shadow Mapping Based on Dual Depth Layers(Eurographics Association, 2003) Weiskopf, Daniel; Ertl, ThomasShadow maps are a widely used means for the generation of shadows although they exhibit aliasing artifacts and problems of numerical precision. In this paper we extend the concept of a single shadow map by introducing dual shadow maps, which are based on the two depth layers that are closest to the light source. Our shadow algorithm takes into account these two depth values and computes an adaptive depth bias to achieve a robust determination of shadowed regions. Dual depth mapping only modifies the construction of the shadow map and can therefore be combined with other extensions such as filtering, perspective shadow maps, or adaptive shadow maps. Our approach can be mapped to graphics hardware for interactive applications and can also be used in high-quality software renderers.Item Interactive High-Quality Visualization of Higher-Order Finite Elements(The Eurographics Association and Blackwell Publishing Ltd, 2010) Ueffinger, Markus; Frey, Steffen; Ertl, ThomasHigher-order finite element methods have emerged as an important discretization scheme for simulation. They are increasingly used in contemporary numerical solvers, generating a new class of data that must be analyzed by scientists and engineers. Currently available visualization tools for this type of data are either batch oriented or limited to certain cell types and polynomial degrees. Other approaches approximate higher-order data by resampling resulting in trade-offs in interactivity and quality. To overcome these limitations, we have developed a distributed visualization system which allows for interactive exploration of non-conforming unstructured grids, resulting from space-time discontinuous Galerkin simulations, in which each cell has its own higher-order polynomial solution. Our system employs GPU-based raycasting for direct volume rendering of complex grids which feature non-convex, curvilinear cells with varying polynomial degree. Frequency-based adaptive sampling accounts for the high variations along rays. For distribution across a GPU cluster, the initial object-space partitioning is determined by cell characteristics like the polynomial degree and is adapted at runtime by a load balancing mechanism. The performance and utility of our system is evaluated for different aeroacoustic simulations involving the propagation of shock fronts.Item An E-Learning Course on Scientific Visualization(The Eurographics Association, 2007) Taras, Christiane; Rotard, Martin; Ertl, Thomas; Isabel Navazo and Petr FelkelIn this paper we present an e-learning course on scientific visualization. Based on over ten years of teaching experiences in this field, we have created a multimedia online course which we use as additional material for our lecture. The course will be made publicly available so that not only our students but all people interested in the field of scientific visualization can benefit from the materials we have prepared. In the course important visualization techniques and algorithms are discussed. The main goal is to lay the foundamentals for future specialists and researchers in the field of scientific visualization.Item FTLE Computation Beyond First-Order Approximation(The Eurographics Association, 2012) Üffinger, Markus; Sadlo, Filip; Kirby, Mike; Hansen, Charles; Ertl, Thomas; Carlos Andujar and Enrico PuppoWe present a framework for different approaches to finite-time Lyapunov exponent (FTLE) computation for 2D vector fields, based on the advection of seeding circles. On the one hand it unifies the popular flow map approach with techniques based on the evaluation of distinguished trajectories, such as renormalization. On the other hand it allows for the exploration of their order of approximation (first-order approximation representing the flow map gradient). Using this framework, we derive a measure for nonlinearity of the flow map, that brings us to the definition of a new FTLE approach. We also show how the nonlinearity measure can be used as a criterion for flow map refinement for more accurate FTLE computation, and we demonstrate that ridge extraction in supersampled FTLE leads to superior ridge quality.Item Fast Flow-based Distance Quantification and Interpolation for High-Resolution Density Distributions(The Eurographics Association, 2017) Frey, Steffen; Ertl, Thomas; Adrien Peytavie and Carles BoschWe present a GPU-targeted algorithm for the efficient direct computation of distances and interpolates between high-resolution density distributions without requiring any kind of intermediate representation like features. It is based on a previously published multi-core approach, and substantially improves its performance already on the same CPU hardware due to algorithmic improvements. As we explicitly target a manycore-friendly algorithm design, we further achieve significant speedups by running on a GPU. This paper quickly reviews the previous approach, and explicitly discusses the analysis of algorithmic characteristics as well as hardware architectural considerations on which our redesign was based. We demonstrate the performance and results of our technique by means of several transitions between volume data sets.Item Spline-based Decomposition of Streamed Particle Trajectories for Efficient Transfer and Analysis(The Eurographics Association, 2017) Scharnowski, Katrin; Frey, Steffen; Raffin, Bruno; Ertl, Thomas; Adrien Peytavie and Carles BoschWe introduce an approach for distributed processing and efficient storage of noisy particle trajectories, and present visual analysis techniques that directly operate on the generated representation. For efficient storage, we decompose individual trajectories into a smooth representation and a high frequency part. Our smooth representation is generated by fitting Hermite Splines to a series of time windows, adhering to a certain error bound. This directly supports scenarios involving in situ and streaming data processing. We show how the individually fitted splines can afterwards be combined into one spline posessing the same mathematical properties, i.e. C1 continuity as well as our error bound. The fitted splines are typically significantly smaller than the original data, and can therefore be used, e.g., for an online monitoring and analysis of distributed particle simulations. The high frequency part can be used to reconstruct the original data, or could also be discarded in scenarios with limited storage capabilities. Finally, we demonstrate the utility of our smooth representation for different analysis queries using real world data.Item Item Programmable Graphics Hardware for Interactive Visualization(Eurographics Association, 2002) Ertl, Thomas; Weiskopf, Daniel; Kraus, Martin; Engel, Klaus; Weiler, Manfred; Hopf, Matthias; Röttger, Stefan; Rezk-Salama, Christof-