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End date: 2009 × Author: Dachsbacher, Carsten × Start date: 2003 ×

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Now showing 1 - 10 of 10
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    Translucent Shadow Maps
    (The Eurographics Association, 2003) Dachsbacher, Carsten; Stamminger, Marc; Philip Dutre and Frank Suykens and Per H. Christensen and Daniel Cohen-Or
    Shadow maps are a very efficient means to add shadows to arbitrary scenes. In this paper, we introduce Translucent Shadow Maps, an extension to shadow maps which allows very efficient rendering of sub-surface scattering. Translucent Shadow Maps contain depth and incident light information. Sub-surface scattering is computed on-the-fly during rendering by filtering the shadow map neighborhood. This filtering is done efficiently using a hierarchical approach. We describe optimizations for an implementation of Translucent Shadow Maps on contemporary graphics hardware, that can render complex translucent objects with varying light and material properties in real-time.
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    Point-Based Computer Graphics
    (Eurographics Association, 2003) Alexa, Marc; Dachsbacher, Carsten; Gross, Markus; Pauly, Mark; van Baar, Jeroen; Zwicker, Matthias
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    Realtime Isosurface Extraction with Graphics Hardware
    (Eurographics Association, 2004) Reck, Frank; Dachsbacher, Carsten; Grosso, Roberto; Greiner, Günther; Stamminger, Marc; M. Alexa and E. Galin
    In this paper we introduce a method for the display of isosurfaces extracted from unstructured tetrahedral grids. Our algorithm completely runs on the graphics hardware. The tetrahedra are streamed into a vertex program, which extracts the surface for the given isovalue and immediately renders it. The triangles are not stored explicitly but are computed during rendering time, so the user can modify the isovalue with immediate feedback. If the tetrahedra entirely fit into video memory, we achieve a throughput of more than nine million tetrahedra per second. Our performance can be further improved by using a hybrid method which pre-selects tetrahedra containing the isovalue. We compare our approach with a pure CPU based implementation which achieves about half the performance of our hardware accelerated method.
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    Structure-Preserving Reshape for Textured Architectural Scenes
    (The Eurographics Association and Blackwell Publishing Ltd, 2009) Cabral, Marcio; Lefebvre, Sylvain; Dachsbacher, Carsten; Drettakis, George
    Modeling large architectural environments is a difficult task due to the intricate nature of these models and the complex dependencies between the structures represented. Moreover, textures are an essential part of architectural models. While the number of geometric primitives is usually relatively low (i.e., many walls are at surfaces), textures actually contain many detailed architectural elements.We present an approach for modeling architectural scenes by reshaping and combining existing textured models, where the manipulation of the geometry and texture are tightly coupled. For geometry, preserving angles such as oor orientation or vertical walls is of key importance. We thus allow the user to interactively modify lengths of edges, while constraining angles. Our texture reshaping solution introduces a measure of directional autosimilarity to focus stretching in areas of stochastic content and to preserve details in such areas.We show results on several challenging models, and show two applications: Building complex road structures from simple initial pieces and creating complex game-levels from an existing game based on pre-existing model pieces.
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    Rendering Procedural Terrain by Geometry Image Warping
    (The Eurographics Association, 2004) Dachsbacher, Carsten; Stamminger, Marc; Alexander Keller and Henrik Wann Jensen
    We describe an approach for rendering large terrains in real-time. A digital elevation map defines the rough shape of the terrain. During rendering, procedural geometric and texture detail is added by the graphics hardware. We show, how quad meshes can be generated quickly that have a locally varying resolution that is optimized for the inclusion of procedural detail.We obtain these distorted meshes by importance based warping of geometry images. The resulting quad mesh can then be rendered very efficiently by graphics hardware, which also adds all visible procedural detail using vertex and fragment programs.
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    Instant Sound Scattering
    (The Eurographics Association, 2007) Tsingos, Nicolas; Dachsbacher, Carsten; Lefebvre, Sylvain; Dellepiane, Matteo; Jan Kautz and Sumanta Pattanaik
    Real-time sound rendering engines often render occlusion and early sound reflection effects using geometrical techniques such as ray or beam tracing. They can only achieve interactive rendering for environments of low local complexity resulting in crude effects which can degrade the sense of immersion. However, surface detail or complex dynamic geometry has a strong influence on sound propagation and the resulting auditory perception. This paper focuses on high-quality modeling of first-order sound scattering. Based on a surface-integral formulation and the Kirchhoff approximation, we propose an efficient evaluation of scattering effects, including both diffraction and reflection, that leverages programmable graphics hardware for dense sampling of complex surfaces. We evaluate possible surface simplification techniques and show that combined normal and displacement maps can be successfully used for audio scattering calculations. We present an auralization framework that can render scattering effects interactively thus providing a more compelling experience. We demonstrate that, while only considering first order phenomena, our approach can provide realistic results for a number of practical interactive applications. It can also process highly detailed models containing millions of unorganized triangles in minutes, generating high-quality scattering filters. Resulting simulations compare well with on-site recordings showing that the Kirchhoff approximation can be used for complex scattering problems.
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    The Gödel Engine - An Interactive Approach to Visualization in General Relativity
    (The Eurographics Association and Blackwell Publishing Ltd., 2009) Grave, Frank; Müller, Thomas; Dachsbacher, Carsten; Wunner, Günter; H.-C. Hege, I. Hotz, and T. Munzner
    We present a methodical new approach to visualize the aspects of general relativity from a self-centered perspective. We focus on the visualization of the Gödel universe, which is an exact solution to Einstein s field equations of general relativity. This model provides astounding features such as the existence of an optical horizon and the possibility of time travel. Although we know that our universe is not of Gödel type, we can using this solution to Einstein s equations visualize and understand the effects resulting from the theory of relativity, which itself has been verified on the large scale in numerous experiments over the last century. We derive the analytical solution to the geodesic equations of Gödel s universe for special initial conditions. Along with programmable graphics hardware we achieve a tremendous speedup for the visualization of general relativity. This enables us to interactively explore the physical aspects and optical effects of Gödel s universe. We also demonstrate how the analytical solution enables dynamic lighting with local illumination models. Our implementation is tailored for Gödel s universe and five orders of magnitude faster than previous approaches. It can be adapted to manifolds for which an analytical expression of the propagation of light is available.
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    An Interactive Perceptual Rendering Pipeline using Contrast and Spatial Masking
    (The Eurographics Association, 2007) Drettakis, George; Bonneel, Nicolas; Dachsbacher, Carsten; Lefebvre, Sylvain; Schwarz, Michael; Viaud-Delmon, Isabelle; Jan Kautz and Sumanta Pattanaik
    We present a new perceptual rendering pipeline which takes into account visual masking due to contrast and spatial frequency. Our framework predicts inter-object, scene-level masking caused by partial occlusion and shadows. It is designed for interactive applications and runs efficiently on the GPU. This is achieved using a layer-based approach together with an efficient GPU-based computation of threshold maps. We build upon this prediction framework to introduce a perceptually-based level of detail control algorithm. We conducted a perceptual user study which indicates that our perceptual pipeline generates results which are consistent with what the user perceives. Our results demonstrate significant quality improvement for scenes with masking due to frequencies and contrast, such as masking due to trees or foliage, or due to high-frequency shadows.
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    Data-Parallel Hierarchical Link Creation for Radiosity
    (The Eurographics Association, 2009) Meyer, Quirin; Eisenacher, Christian; Stamminger, Marc; Dachsbacher, Carsten; Kurt Debattista and Daniel Weiskopf and Joao Comba
    The efficient simulation of mutual light exchange for radiosity-like methods has been demonstrated on GPUs. However, those approaches require a suitable set of links and hierarchical data structures, prepared in an expensive preprocessing step. We present a fast, data-parallel method to create links and a compact tree of patches. We demonstrate our approach for Antiradiance and Implicit Visibility. Our algorithm is able to create up to 50 M links per second on an Nvidia GTX 260, allowing fully dynamic scenes at interactive frame rates.
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    CUDASA: Compute Unified Device and Systems Architecture
    (The Eurographics Association, 2008) Strengert, Magnus; Müller, Christoph; Dachsbacher, Carsten; Ertl, Thomas; Jean M. Favre and Kwan-Liu Ma
    We present an extension to the CUDA programming language which extends parallelism to multi-GPU systems and GPU-cluster environments. Following the existing model, which exposes the internal parallelism of GPUs, our extended programming language provides a consistent development interface for additional, higher levels of parallel abstraction from the bus and network interconnects. The newly introduced layers provide the key features specific to the architecture and programmability of current graphics hardware while the underlying communica- tion and scheduling mechanisms are completely hidden from the user. All extensions to the original programming language are handled by a self-contained compiler which is easily embedded into the CUDA compile process. We evaluate our system using two different sample applications and discuss scaling behavior and performance on different system architectures.