Issue 5

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https://diglib.eg.org/handle/10.2312/76

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    Adaptive Enumeration of Implicit Surfaces with Affine Arithmetic
    (Blackwell Science Ltd and the Eurographics Association, 1996) de Figueiredo, Luiz Henrique; Stolfi, Jorge
    We discuss adaptive enumeration and rendering methods for implicit surfaces, using octrees computed with affine arithmetic, a new tool for range analysis. Affine arithmetic is similar to standard interval arithmetic, but takes into account correlations between operands and sub-formulas, generally providing much tighter bounds for the computed quantities. The resulting octrees are accordingly much smaller, and the rendering faster.
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    Adaptive Sampling of Implicit Surfaces for Interactive Modelling and Animation
    (Blackwell Science Ltd and the Eurographics Association, 1996) Desbrun, Mathieu; Tsingos, Nicolas; Gascuel, Marie-Paule
    This paper presents a new adaptive sampling method for implicit surfaces that can be used in both interactive modelling and animation. The algorithm samples implicit objects composed of blending primitives and efficiently maintains this sampling over time, even when their topology changes (during fractures and fusions). It provides two complementary modes of immediate visualization: displaying"scales" lying on the surface, or a"primitive-wise" polygonization. The sampling method efficiently avoids unwanted blending between different parts of an object. Moreover, it can be used for partitioning an implicit surface into local bounding boxes that will accelerate collision detection during animation and ray-intersections during final rendering.
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    Approximate Conversion of Parametric to Implicit Surfaces
    (Blackwell Science Ltd and the Eurographics Association, 1996) Velho, Luiz; Gomes, Jonas
    In this paper we present a framework for the approximate conversion of parametric to implicit surfaces. It takes as input a parametric description and generates a piecewise analytic implicit representation. The conversion process consists of three steps: 1) the parametric surface is rasterized into a volumetric characteristic function. 2) this binary function is converted into a volume array corresponding to samples of a smooth implicit function. 3) this volumetric representation is converted into a multiscale B-spline model. This method is based on wavelet analysis and synthesis techniques and is very general. It can convert to implicit form any geometric object that is suitable for discretization into a characteristic function.
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    Efficient Hierarchical Refinement and Clustering for Radiosity in Complex Environments
    (Blackwell Science Ltd and the Eurographics Association, 1996) Gibson, S.; Hubbold, R.J.
    Generating accurate radiosity solutions of very complex environments is a time-consuming problem. We present a rapid hierarchical algorithm that enables such solutions to be computed quickly and efficiently. Firstly, a new technique for bounding the error in the transfer of radiosity between surfaces is discussed, incorporating bounds on form factors, visibility, irradiance, and reflectance over textured surfaces. This technique is then applied to the problem of bounding radiosity transfer between clusters of surfaces, leading to a fast, practical clustering algorithm that builds on the previous work of Sillion1. Volumes are used to represent clusters of small surfaces, but unlike previous algorithms, the orientations of surfaces inside each cluster are accounted for in both the error bound and radiosity transfer. This enables an accurate solution to be generated very efficiently, and results are presented demonstrating the performance of the algorithm on a variety of complex models, one containing almost a quarter of a million initial surfaces.
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    The Production of Volume Data from Triangular Meshes Using Voxelisation
    (Blackwell Science Ltd and the Eurographics Association, 1996) Jones, Mark W.
    Voxelisation is the term given to the process of converting data from one source type into a three dimensional volume of data values. The techniques known collectively as volume visualisation can then be applied to the data in order to produce a graphical representation of the object. This paper gives a practical approach to the voxelisation of data in the form of triangular meshes, and demonstrates the use of the method on various datasets. Visualisation is achieved by a method also described in the paper.