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Has files: true × Author: Seidel, Hans-Peter × Start date: 1990 × End date: 1999 ×

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Now showing 1 - 10 of 22
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    Using Procedural RenderMan Shaders for Global Illurnination
    (Blackwell Science Ltd and the Eurographics Association, 1995) Slusallek, Philipp; Pflaum, Thomas; Seidel, Hans-Peter
    Global illumination techniques like radiosity or Monte-Carlo ray-tracing are becoming standard features of rendering systems. However, there is currently no accepted interface format which supports an appropriate physically-based scene description. In this paper we present extensions to the well-known RenderMan interface, which allow for a physically based scene description and support advanced global illumination techniques. Special emphasis has been laid on the support for procedural descriptions of reflection and emission by RenderMan surface shaders. So far, they could not be used with most global illumination algorithms. The extensions have been implemented in a physically-based rendering system and are illustrated with examples.
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    Editorial
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Coquillart, Sabine; Seidel, Hans-Peter
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    Editorial
    (Blackwell Publishers Ltd and the Eurographics Association, 1999) Coquillart, Sabine; Seidel, Hans-Peter
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    Control Points for Multivariate B-Spline Surfaces over Arbitrary Triangulations
    (Blackwell Science Ltd and the Eurographics Association, 1991) Fong, Philip; Seidel, Hans-Peter
    This paper describes first results of a test implementation that implements the new multivariate B-splines as recently developed by Dahmen et al. 10for quadratics and cubics. The surface scheme is based on blending functions and control points and allows the modelling of Ck? 1 -continuous piecewise polynomial surfaces of degree k over arbitrary triangulations of the parameter plane. The surface scheme exhibits both affine invariance and the convex hull property, and the control points can be used to manipulate the shape of the surface locally. Additional degrees of freedom in the underlying knot net allow for the modelling of discontinuities. Explicit formulas are given for the representation of polynomials and piecewise polynomials as linear combinations of B-splines.
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    TRIMO A Workstation-Based Interactive System for the Generation, Manipulation, and Display of Surfaces over Arbitrary Topological Meshes
    (Eurographics Association, 1990) Slusallek, Philipp B.; Seidel, Hans-Peter
    TRIMO has been designed as a workstation-based interactive system for the generation, manipulation, and display of surfaces over arbitrary toplogical meshes. In addition to rational tensor product Bezier and B-spline surfaces, TRIMO also supports piecewise rational triangular Bezier and B-patch surfaces. TRIMO has been implemented in C++ under the X Window System. Special emphasis has been given to a hierarchical data structure and to a menu-and-mouse-driven hierarchical user interface.
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    Editorial
    (Blackwell Publishers Ltd and the Eurographics Association, 1997) Coquillart, Sabine; Seidel, Hans-Peter
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    Editorial
    (Blackwell Publishers Ltd and the Eurographics Association, 1997) Seidel, Hans-Peter; Coquillart, Sabine
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    Editorial
    (Blackwell Publishers Ltd and the Eurographics Association, 1999) Coquillart, Sabine; Seidel, Hans-Peter
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    Visualization of Regular Polytopes in Three and Four Dimensions
    (Blackwell Science Ltd and the Eurographics Association, 1994) Hausmann, Barbara; Seidel, Hans-Peter
    Nontrivial regular polytopes only exist in three and four dimensions. This paper describes a software package that allows to interactively visualize and analyze these regular polytopes. The following four tools are available: Display of the Schlegel diagrams, perspective projections with the possibility of interactively rotating the polytope in three-/four-dimensional space before projection, interactive slicing along various directions, cut-throughs and fold-downs. Various examples illustrate the approach.
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    Using Subdivision on Hierarchical Data to Reconstruct Radiosity Distribution
    (Blackwell Publishers Ltd and the Eurographics Association, 1997) Kobbelt, Leif; Stamminger, Marc; Seidel, Hans-Peter
    Computing 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.