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Item Interactive Rendering of Atmospheric Scattering Effects Using Graphics Hardware(The Eurographics Association, 2002) Dobashi, Yoshinori; Yamamoto, Tsuyoshi; Nishita, Tomoyuki; Thomas Ertl and Wolfgang Heidrich and Michael DoggettTo create realistic images using computer graphics, an important element to consider is atmospheric scattering, that is, the phenomenon by which light is scattered by small particles in the air. This effect is the cause of the light beams produced by spotlights, shafts of light, foggy scenes, the bluish appearance of the earth s atmosphere, and so on. This paper proposes a fast method for rendering the atmospheric scattering effects based on actual physical phenomena. In the proposed method, look-up tables are prepared to store the intensities of the scattered light, and these are then used as textures. Realistic images are then created at interactive rates by making use of graphics hardware.Item Adaptive Texture Maps(The Eurographics Association, 2002) Kraus, Martin; Ertl, Thomas; Thomas Ertl and Wolfgang Heidrich and Michael DoggettWe introduce several new variants of hardware-based adaptive texture maps and present applications in two, three, and four dimensions. In particular, we discuss representations of images and volumes with locally adaptive resolution, lossless compression of light fields, and vector quantization of volume data. All corresponding texture decoders were successfully integrated into the programmable texturing pipeline of commercial off-the-shelf graphics hardware.Item The Ray Engine(The Eurographics Association, 2002) Carr, Nathan A.; Hall, Jesse D.; Hart, John C.; Thomas Ertl and Wolfgang Heidrich and Michael DoggettAssisted by recent advances in programmable graphics hardware, fast rasterization-based techniques have made significant progress in photorealistic rendering, but still only render a subset of the effects possible with ray tracing. We are closing this gap with the implementation of ray-triangle intersection as a pixel shader on existing hardware. This GPU ray-intersection implementation reconfigures the geometry engine into a ray engine that efficiently intersects caches of rays for a wide variety of host-based rendering tasks, including ray tracing, path tracing, form factor computation, photon mapping, subsurface scattering and general visibility processing.Item Low Latency Photon Mapping Using Block Hashing(The Eurographics Association, 2002) Ma, Vincent C. H.; McCool, Michael D.; Thomas Ertl and Wolfgang Heidrich and Michael DoggettFor hardware accelerated rendering, photon mapping is especially useful for simulating caustic lighting effects on non-Lambertian surfaces. However, an efficient hardware algorithm for the computation of the k nearest neighbours to a sample point is required. Existing algorithms are often based on recursive spatial subdivision techniques, such as kd-trees. However, hardware implementation of a tree-based algorithm would have a high latency, or would require a large cache to avoid this latency on average. We present a neighbourhood-preserving hashing algorithm that is low-latency and has sub-linear access time. This algorithm is more amenable to fine-scale parallelism than tree-based recursive spatial subdivision, and maps well onto coherent block-oriented pipelined memory access. These properties make the algorithm suitable for implementation using future programmable fragment shaders with only one stage of dependent texturing.Item SaarCOR - A Hardware Architecture for Ray Tracing(The Eurographics Association, 2002) Schmittler, Jörg; Wald, Ingo; Slusallek, Philipp; Thomas Ertl and Wolfgang Heidrich and Michael DoggettThe ray tracing algorithm is well-known for its ability to generate high-quality images and its flexibility to support advanced rendering and lighting effects. Interactive ray tracing has been shown to work well on clusters of PCs and supercomputers but direct hardware support for ray tracing has been difficult to implement. In this paper, we present a new, scalable, modular, and highly efficient hardware architecture for real-time ray tracing. It achieves high performance with extremely low memory bandwidth requirements by efficiently tracing bundles of rays. The architecture is easily configurable to support a variety of workloads. For OpenGL-like scenes our architecture offers performance comparable to state-of-the-art rasterization chips. In addition, it supports all the usual ray tracing features including exact shadows, reflections, and refraction and is capable of efficiently handling complex scenes with millions of triangles. The architecture and its performance in different configurations is analyzed based on cycle-accurate simulations.Item VIZARD II: A Reconfigurable Interactive Volume Rendering System(The Eurographics Association, 2002) Meißner, M.; Kanus, U.; Wetekam, G.; Hirche, J.; Ehlert, A.; Straßer, W.; Doggett, M.; Forthmann, P.; Proksa, R.; Thomas Ertl and Wolfgang Heidrich and Michael DoggettThis paper presents a reconfigurable, hardware accelerated, volume rendering system for high quality perspective ray casting. The volume rendering accelerator performs ray casting by calculating the path of the ray through the volume using a programmable Xilinx Virtex FPGA which provides fast design changes and low cost development. Volume datasets are stored on the card in low profile DIMMs with standard connectors allowing both, large datasets up to 1 GByte with 32 bit per voxel, and easy upgrades to larger memory capacities. Per-sample Phong shading and post-classification is performed in hardware, giving immediate feedback to changes in the visualization of a dataset. Adding new features, such as pre-integrated classification, can be accomplished using the existing card without expensive and time consuming redesigns. The card can also be used for medical image reconstruction by reconfiguring the FPGA broadening its usefulness for end users. For the first time, users are able to generate high quality perspective images as required for applications such as virtual endoscopy and colonoscopy, and stereoscopic image generation.