14 results
Search Results
Now showing 1 - 10 of 14
Item Editorial(Blackwell Publishers Ltd and the Eurographics Association, 1998) Coquillart, Sabine; Seidel, Hans-PeterItem Editorial(Blackwell Publishers Ltd and the Eurographics Association, 1999) Coquillart, Sabine; Seidel, Hans-PeterItem Editorial(Blackwell Publishers Ltd and the Eurographics Association, 1997) Coquillart, Sabine; Seidel, Hans-PeterItem Editorial(Blackwell Publishers Ltd and the Eurographics Association, 1997) Seidel, Hans-Peter; Coquillart, SabineItem Editorial(Blackwell Publishers Ltd and the Eurographics Association, 1999) Coquillart, Sabine; Seidel, Hans-PeterItem Using Subdivision on Hierarchical Data to Reconstruct Radiosity Distribution(Blackwell Publishers Ltd and the Eurographics Association, 1997) Kobbelt, Leif; Stamminger, Marc; Seidel, Hans-PeterComputing global illumination by finite element techniques usually generates a piecewise constant approximation of the radiosity distribution on surfaces. Directly displaying such scenes generates artefacts due to discretization errors. We propose to remedy this drawback by considering the piecewise constant output to be samples of a (piecewise) smooth function in object space and reconstruct this function by applying a binary subdivision scheme. We design custom taylored subdivision schemes with quadratic precision for the efficient refinement of cell- or pixel-type data. The technique naturally allows to reconstruct functions from non-uniform samples which result from adaptive binary splitting of the original domain (quadtree). This type of output is produced, e.g., by hierarchical radiosity algorithms. The result of the subdivision process can be mapped as a texture on the respective surface patch which allows to exploit graphics hardware for considerably accelerating the display.Item Adaptive Acquisition of Lumigraphs from Synthetic Scenes(Blackwell Publishers Ltd and the Eurographics Association, 1999) Schirmacher, Hartmut; Heidrich, Wolfgang; Seidel, Hans-PeterLight fields and Lumigraphs are capable of rendering scenes of arbitrary geometrical or illumination complexity in real time. They are thus interesting ways of interacting with both recorded real-world and high-quality synthetic scenes.Unfortunately, both light fields and Lumigraph rely on a dense sampling of the illumination to provide a good rendering quality. This induces high costs both in terms of storage requirements and computational resources for the image acquisition. Techniques for acquiring adaptive light field and Lumigraph representations are thus mandatory for practical applications.In this paper we present a method for the adaptive acquisition of images for Lumigraphs from synthetic scenes. Using image warping to predict the potential improvement in image quality when adding a certain view, we decide which new views of the scene should be rendered and added to the light field. This a-priori error estimator accounts for both visibility problems and illumination effects such as specular highlights.Item Light Field Techniques for Reflections and Refractions(The Eurographics Association, 1999) Heidrich, Wolfgang; Lensch, Hendrik; Cohen, Michael F.; Seidel, Hans-Peter; Dani Lischinski and Greg Ward LarsonReflections and refractions are important visual effects that have long been considered too costly for interactive applications. Although most contemporary graphics hardware supports reflections off curved surfaces in the form of environment maps, refractions in thick, solid objects cannot be handled with this approach, and the simplifying assumptions of environment maps also produce visible artifacts for reflections. Only recently have researchers developed techniques for the interactive rendering of true reflections and refractions in curved objects. This paper introduces a new, light field based approach to achieving this goal. The method is based on a strict decoupling of geometry and illumination. Hardware support for all stages of the technique is possible through existing extensions of the OpenGL rendering pipeline. In addition, we also discuss storage issues and introduce methods for handling vector-quantized data with graphics hardware.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 Bounded Radiosity - Illumination on General Surfaces and Clusters(Blackwell Publishers Ltd and the Eurographics Association, 1997) Stamminger, Marc; Slusallek, Philipp; Seidel, Hans-PeterTraditionally, Radiosity algorithms have been restricted to scenes made from planar patches. Most algorithms for computing form factors and the subdivision criterion for hierarchical methods implicitly assume planar patches. In this paper, we present a new radiosity algorithm that is solely based on simple geometric information about surface elements, namely their bounding boxes and cone of normals. Using this information allows to compute efficient error bounds that can be used for the subdivision oracle and for computing the energy transfer. Due to the simple interface to geometric objects, our algorithm not only allows for computing illumination on general curved surfaces, but it can also be directly applied to a hieararchy of clusters. Several examples demonstrate the advantages of the new approach.