5 results
Search Results
Now showing 1 - 5 of 5
Item Adaptive View Dependent Tessellation of Displacement Maps(The Eurographics Association, 2000) Doggett, Michael; Hirche, Johannes; I. Buck and G. Humphreys and P. HanrahanDisplacement Mapping is an effective technique for encoding the high levels of detail found in today s triangle based surface models. Extending the hardware rendering pipeline to be capable of handling displacement maps as geometric primitives, will allow highly detailed models to be constructed without requiring large numbers of triangles to be passed from the CPU to the graphics pipeline. We present a new approach based on recursive tessellation that adapts to the surface complexity described by the displacement map. We also ensure that the resolution of the displaced mesh is tessellated with respect to the current view point. Our tessellation scheme performs all tests only on triangle edges to avoid generating cracks on the displaced surface. The main decision for vertex insertion is based on two comparisons involving the average height surrounding the vertices and the normals at the vertices. Individually, the tests will fail to tessellate a mesh satisfactorily, but their combination achieves good results. We propose several additions to the typical hardware rendering pipeline in order to achieve displacement map rendering in hardware. The mesh tessellation is placed within the rendering pipeline so that we can take advantage of the pre-existing vertex transformation units to perform the setup calculations for our view dependent test. Our method adds only simple arithmetic and comparison operations to the graphics pipeline and makes use of existing units for calculations wherever possible.Item Hardware-Accelerated Free-Form Deformation(The Eurographics Association, 2000) Chua, Clint; Neumann, Ulrich; I. Buck and G. Humphreys and P. HanrahanHardware-acceleration for geometric deformation is developed in the framework of an extension to the OpenGL specification. The method requires an addition to the front-end of the OpenGL rendering pipeline and an appropriate OpenGL primitive. Our approach is to implement general geometric deformations so the system supports additional layers of abstraction, including physically based simulations. This approach would support a wide range of users with an accelerated implementation of a wellunderstood deformation method, reducing the need for software deformation engines and the execution time penalty associated with them.Item Tile-Based Texture Mapping on Graphics Hardware(The Eurographics Association, 2004) Wei, Li-Yi; Tomas Akenine-Moeller and Michael McCoolTexture mapping has been a fundamental feature for commodity graphics hardware. However, a key challenge for texture mapping is how to store and manage large textures on graphics processors. In this paper, we present a tilebased texture mapping algorithm by which we only have to physically store a small set of texture tiles instead of a large texture. Our algorithm generates an arbitrarily large and non-periodic virtual texture map from the small set of stored texture tiles. Because we only have to store a small set of tiles, it minimizes the storage requirement to a small constant, regardless of the size of the virtual texture. In addition, the tiles are generated and packed into a single texture map, so that the hardware filtering of this packed texture map corresponds directly to the filtering of the virtual texture. We implement our algorithm as a fragment program, and demonstrate performance on latest graphics processors.Item Comparing Reyes and OpenGL on a Stream Architecture(The Eurographics Association, 2002) Owens, John D.; Khailany, Brucek; Towles, Brian; Dally, William J.; Thomas Ertl and Wolfgang Heidrich and Michael DoggettThe OpenGL and Reyes rendering pipelines each render complex scenes from similar scene descriptions but differ in their internal pipeline organizations. While the OpenGL organization has dominated hardware architectures over the past twenty years, a Reyes organization differs in several important ways from OpenGL, including a shader coordinate system that supports coherent texture accesses, a single shader in the vertex stage, and tessellation and sampling instead of triangle rasterization. Hardware for the OpenGL pipeline has been well-studied, but the lack of a hardware Reyes implementation has prevented a comparison between the two pipelines. We analyze and compare implementations of an OpenGL and a Reyes pipeline on the Imagine stream processor, a high performance programmable processor for media applications. This comparison both demonstrates the applicability of Reyes for hardware implementation and exposes many issues that architects will face in implementing Reyes in hardware, in particular the need for efficient subdivision algorithms and implementations.Item A Multigrid Solver for Boundary Value Problems Using Programmable Graphics Hardware(The Eurographics Association, 2003) Goodnight, Nolan; Woolley, Cliff; Lewin, Gregory; Luebke, David; Humphreys, Greg; M. Doggett and W. Heidrich and W. Mark and A. SchillingWe present a case study in the application of graphics hardware to general-purpose numeric computing. Specifi- cally, we describe a system, built on programmable graphics hardware, able to solve a variety of partial differential equations with complex boundary conditions. Many areas of graphics, simulation, and computational science require efficient techniques for solving such equations. Our system implements the multigrid method, a fast and popular approach to solving large boundary value problems. We demonstrate the viability of this technique by using it to accelerate three applications: simulation of heat transfer, modeling of fluid mechanics, and tone mapping of high dynamic range images. We analyze the performance of our solver and discuss several issues, including techniques for improving the computational efficiency of iterative grid-based computations for the GPU.