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Item Extending Graphics Hardware For Occlusion Queries In OpenGL(The Eurographics Association, 1998) Bartz, Dirk; Meißner, Michael; Hüttner, Tobias; S. N. SpencerFor interactive rendering of large polygonal objects, fast visibility queries are necessary to quickly decide whether polygonal objects are visible and need to be rendered. None of the numerous published algorithms provide visibility performance for interactive rendering of large models. In this paper, we propose an OpenGL extension for fast occlusion queries. Added after the depth test stage of the OpenGL rendering pipeline. our algorithm provides fast queries to establish the occlusion of polygonal objects. Furthermore, hardware aspects of this proposal are discussed and possible implementations on two different graphics architectures are presented.Item PAVLOV: A Programmable Architecture for Volume Processing(The Eurographics Association, 1998) Kreeger, Kevin; Kaufman, Arie; S. N. SpencerWe present a parallel 2D mesh connected architecture with SIMD processing elements. The design allows for real-time volume rendering as well as interactive 30 segmentation and 1D feature extraction. This is possible because the SIMD processing elements are programmable, a feature which also allows the use of many different rendering algorithms. We present an algorithm which, with the addition of hardware resources, provides conflict free access to volume slices along any of the three major axes. The volume access conflict has been the main reason why previous similar architectures could not perform real-time volume rendering. We present the performance of preliminary algorithms on a software simulator of the architecture design.Item Neon: A Single-Chip 3D Workstation Graphics Accelerator(The Eurographics Association, 1998) McCormack, Joel; McNamara, Robert; Gianos, Christopher; Seiler, Larry; Jouppi, Norman P.; Correll, Ken; S. N. SpencerHigh-performance 3D graphics accelerators traditionally require multiple chips on multiple boards, including geometry, rasterizing, pixel processing, and texture mapping chips. These designs are often scalable: they can increase performance by using more chips. Scalability has obvious costs: a minimal configuration needs several chips, and some configurations must replicate texture maps. A less obvious cost is the almost irresistible temptation to replicate chips to increase performance, rather than to design individual chips for higher performance in the first place. In contrast, Neon is a single chip that performs like a multichip design. Neon accelerates OpenGL [19] 3D rendering, as well as X11 [20] and Windows/NT 2D rendering. Since our pin budget limited peak memory bandwidth, we designed Neon from the memory system upward in order to reduce bandwidth requirements. Neon has no special-purpose memories; its eight independent 32-bit memory controllers can access color buffers, 1. depth buffers, stencil buffers, and texture data. To fit our gate budget, we shared logic among different operations with similar implementation requirements, and left floating point calculations to Digital s Alpha CPUs. Neon s performance is between HP s Visualize fx<sup>4</sup> and fx<sup>6</sup>, and is well above SGI s MXE for most operations. Neon-based boards cost much less than these competitors, due to a small part count and use of commodity SDRAMs.Item View-independent Environment Maps(The Eurographics Association, 1998) Heidrich, Wolfgang; Seidel, Hans-Peter; S. N. SpencerEnvironment maps are widely used for approximating reflections in hardware-accelerated rendering applications. Unfortunately, the parameterizations for environment maps used in today s graphics hardware severely undersample certain directions, and can thus not be used from multiple viewing directions. Other parameterizations exist, but require operations that would be too expensive for hardware implementations. In this paper we introduce an inexpensive new parameterization for environment maps that allows us to reuse the environment map for any given viewing direction. We describe how, under certain restrictions, these maps can be used today in standard OpenGL implementations. Furthermore, we explore how OpenGL could be extended to support this kind of environment map more directly.Item Gouraud Bump Mapping(The Eurographics Association, 1998) Ernst, I.; Rüsseler, H.; Schulz, H.; Wittig, 0.; S. N. SpencerIn this paper a new low cost bump mapping hardware is prcsented. The new hardware approach does not rely on per pixel lighting, but instead uses Gouraud interpolated triangles. The bump mapping effect is applied by blending the calculated per pixel bump map color onto the fragment s color. This allows realtime animated distant light-sources to react on the specified bump map. The paper further investigates a number of different variants of recently proposed bump engines. These variants range from lowend PC solution to highest quality high-end solutions.