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Compressed Bounding Volume Hierarchies for Efficient Ray Tracing of Disperse Hair
(The Eurographics Association, 2018) Martinek, Magdalena; Stamminger, Marc; Binder, Nikolaus; Keller, Alexander; Beck, Fabian and Dachsbacher, Carsten and Sadlo, Filip
Ray traced human hair is becoming more and more ubiquitous in photorealistic image synthesis. Despite hierarchical data structures for accelerated ray tracing, performance suffers from the bad separability inherent with ensembles of hair strands. We propose a compressed acceleration data structure that improves separability by adaptively subdividing hair fibers. Compression is achieved by storing quantized as well as oriented bounding boxes and an indexing scheme to specify curve segments instead of storing them. We trade memory for speed, as our approach may use more memory, however, in cases of highly curved hair we can double the number of traversed rays per second over prior work. With equal memory we still achieve a speed-up of up to 30%, with equal performance we can reduce memory by up to 30%.
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.
Interactive Sampling and Rendering for Complex and Procedural Geometry
(The Eurographics Association, 2001) Stamminger, Marc; Drettakis, George; S. J. Gortle and K. Myszkowski
We present a new sampling method for procedural and complex geometries, which allows interactive point-based modeling and rendering of such scenes. For a variety of scenes, object-space point sets can be generated rapidly, resulting in a sufficiently dense sampling of the final image. We present an integrated approach that exploits the simplicity of the point primitive. For procedural objects a hierarchical sampling scheme is presented that adapts sample densities locally according to the projected size in the image. Dynamic procedural objects and interactive user manipulation thus become possible. The same scheme is also applied to on-the-fly generation and rendering of terrains, and enables the use of an efficient occlusion culling algorithm. Furthermore, by using points the system enables interactive rendering and simple modification of complex objects (e.g., trees). For display, hardware-accelerated 3-D point rendering is used, but our sampling method can be used by any other point-rendering approach.
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.
Topological Triangle Sorting for Predefined Camera Paths
(The Eurographics Association, 2016) Weber, Christoph; Stamminger, Marc; Matthias Hullin and Marc Stamminger and Tino Weinkauf
We present a preprocessing pipeline for triangle meshes that topologically sorts all triangles for a given camera and scene animation in front-to-back or back-to-front order. This allows us to efficiently render a given animation without depth buffer, and to include transparency. We also remove non-contributing triangles, thus improving render time, especially when applying anti-aliasing. To this end we first record the visible triangles of a sequence of frames. For every frame we create a directed graph storing occlusion information. After a topological sort of this graph, all triangles are sorted properly. The contribution of this paper is the reduction of redundancy by merging the graphs of all frames. The result of our pipeline is a single sorted index buffer, over which we slide a window that yields sorted index buffers for each single frame. Circular dependencies are broken by placing duplicates of the affected triangles in the index buffer. Our sliding window then displays only frame specific triangles in their proper order. We conclude by demonstrating the benefits of removing invisible triangles and disabling the hardware visibility test.
On Floating-Point Normal Vectors
(The Eurographics Association and Blackwell Publishing Ltd, 2010) Meyer, Quirin; Suessmuth, Jochen; Sussner, Gerd; Stamminger, Marc; Greiner, Guenther
In this paper we analyze normal vector representations. We derive the error of the most widely used representation, namely 3D floating-point normal vectors. Based on this analysis, we show that, in theory, the discretization error inherent to single precision floating-point normals can be achieved by 250.2 uniformly distributed normals, addressable by 51 bits. We review common sphere parameterizations and show that octahedron normal vectors perform best: they are fast and stable to compute, have a controllable error, and require only 1 bit more than the theoretical optimal discretization with the same error.
Tutorial 1 -Advanced Radiosity:Complex Scenes and Glossy Reflections
(Eurographics Association, 1999) Stamminger, Marc; Wexler, Daniel; Kresse, Wolfram; Holzschuch, Nicolas; Christensen, Per H.
A lot of research towards global illumination has been focussed on the radiosity method. Nevertheless, it is still a rather academic topic which finds very slowly its way into commercial products. The scope of this tutorial is to describe recent developments in radiosity research that might narrow the gap with commercial applications. The first part of the tutorial course will be given by a pioneer in commercial computer graphics, who will set the stage for the demands of commercial rendering products and assess why radiosity has not been used until now.
Data‐Parallel Decompression of Triangle Mesh Topology
(The Eurographics Association and Blackwell Publishing Ltd., 2012) Meyer, Quirin; Keinert, Benjamin; Sußner, Gerd; Stamminger, Marc; Holly Rushmeier and Oliver Deussen
We propose a lossless, single‐rate triangle mesh topology codec tailored for fast data‐parallel GPU decompression. Our compression scheme coherently orders generalized triangle strips in memory. To unpack generalized triangle strips efficiently, we propose a novel parallel and scalable algorithm. We order vertices coherently to further improve our compression scheme. We use a variable bit‐length code for additional compression benefits, for which we propose a scalable data‐parallel decompression algorithm. For a set of standard benchmark models, we obtain (min: 3.7, med: 4.6, max: 7.6) bits per triangle. Our CUDA decompression requires only about 15% of the time it takes to render the model even with a simple shader.We propose a lossless, single‐rate triangle mesh topology codec tailored for fast data‐parallel GPU decompression. Our compression scheme coherently orders generalized triangle strips in memory. To unpack generalized triangle strips efficiently, we propose a novel parallel and scalable algorithm. We order vertices coherently to further improve our compression scheme. We use a variable bit‐length code for additional compression benefits, for which we propose a scalable data‐parallel decompression algorithm. For a set of standard benchmark models, we obtain (min: 3.7, med: 4.6, max: 7.6) bits per triangle. Our CUDA decompression requires only about 15% of the time it takes to render the model even with a simple shader.
Faster Ray-Traced Shadows for Hybrid Rendering of Fully Dynamic Scenes by Pre-BVH Culling
(The Eurographics Association, 2015) Selgrad, Kai; Müller, Jonas; Stamminger, Marc; Andrea Giachetti and Silvia Biasotti and Marco Tarini
With ever increasing ray traversal and hierarchy construction performance the application of ray tracing to problems often tackled by rasterization-based algorithms is becoming a viable alternative. This is especially desirable as the ground truth for these algorithms is often determined by using ray tracing and thus directly applying it is the simplest way to generate images satisfying the reference. In this paper we propose a very efficient pre-process to speed up the construction and traversal of sub-optimal, but fast-to-build hierarchies used for interactive ray tracing and show how it can be applied to shadow rays in a hybrid environment, where ray tracing is used to sample area lights for scene positions found and shaded via rasterization.
Real-time Local Displacement using Dynamic GPU Memory Management
(ACM, 2013) Schäfer, Henry; Keinert, Benjamin; Stamminger, Marc; Kayvon Fatahalian and Christian Theobalt
We propose a novel method for local displacement events in large scenes, such as scratches, footsteps, or sculpting operations. Deformations are stored as displacements for vertices generated by hardware tessellation. Adaptive mesh refinement, application of the displacement and all involved memory management happen completely on the GPU. We show various extensions to our approach, such as on-the-fly normal computation and multi-resolution editing. In typical game scenes we perform local deformations at arbitrary positions in far less than one millisecond. This makes the method particularly suited for games and interactive sculpting applications.

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