Issue 1

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https://diglib.eg.org/handle/10.2312/72

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    Surface Reconstruction from Unstructured 3D Data
    (Blackwell Science Ltd and the Eurographics Association, 1996) Algorri, Maria-Elena; Schmitt, Francis
    Building 3 0 models from unstructured data is a problem that arises increasingly as new 30 scanning technology is able to produce large and complex databases of full 3 0 information. Huge efforts put into segmenting entire sets of 20 images demand robust tools that are then able to reconstruct any arbitrary 30 surface segmented from the images. In this paper we propose an algorithmic methodology that automatically produces a surface from a set of points in ?3 about which we have no topological knowledge. Our method uses a spatial decomposition and a surface tracking algorithm to produce a rough approximation S of the unknown manifold S. The produced surface S serves as a robust initialisation for a physically based modeling technique that yields the fine details of S and so improves the quality of the reconstruction.
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    Scripting Interactive Physically-Based Motions with Relative Paths and Synchronization
    (Blackwell Science Ltd and the Eurographics Association, 1996) Lamouret, Alexis; Gascuel, Marie-Paule
    This paper presents a novel approach for facilitating the use of physically based models by animators. The idea is to let the user guide motion at a high level of control by giving approximate desired trajectories and synchronization constraints between the objects over time, while a simulation module computes the final motion, dealing with collision detection and response, and enhancing realism.The objects, which are either isolated or components of an articulated structure, are guided through the specification of key-positions and orientations, defined by coordinates that can be fixed or relative to another object. The animation sequence is scripted by specifying a graph of synchronization constraints between objects over time. During the animation, objects automatically regulate their speed in order to meet these constraints.
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    Accelerated Evaluation of Box Splines via a Parallel Inverse FFT
    (Blackwell Science Ltd and the Eurographics Association, 1996) McCool, Michael D.
    Box splines are a multivariate extension of uniform univariate B-splines. Direct evaluation of a box spline basis function can he difficult but they have a relatively simple Fourier transform and can therefore be evaluated with an inverse FFT. Symmetry recursive evaluation of the coefficients, and parallelization can be used to improve absolute performance. A windowing function can also he used to reduce truncation artifacts. We explore all these options in the context of a high-performance parallel implementation. Our goal is the provision of an empirical touchstone for the inverse FFT evaluation of box spline basis functions, for eventual application to forward projection (splat-based) volume rendering.
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    An Efficient Algorithm for Line Clipping by Convex and Non-convex Polyhedra in E3
    (Blackwell Science Ltd and the Eurographics Association, 1996) Skala, Vaclav
    A new algorithm for clipping lines against convex polyhedron with O(N) complexity is given with modification for non-convex polyhedron. The suggested algorithm is faster for higher number of facets of the given polyhedron than the traditional Cyrus-Beck s algorithm. Some principal results of comparison of all algorithms are shown and give some ideas how the proposed algorithm could be used effectively.
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    Animation of Human Diving
    (Blackwell Science Ltd and the Eurographics Association, 1996) Wooten, Wayne L.; Hodgins, Jessica K.
    The motion of a human platform diver was simulated using a dynamic model and a control system. The dynamic model has 32 actuated degrees of freedom and dynamic parameters within the range of those reported in the literature for humans. The control system uses algorithms for balance, jumping, and twisting to initiate the dive, sequences of desired values for proportional-derivative servos to perform the aerial portion of the dice, and a state machine to sequence the actions throughout the dice. The motion of the simulated diver closely resembles video footage of dices performed by human athletes. The control and simulation techniques presented in this paper are useful for providing realistic motion for synthetic actors in computer animations and virtual environments and may some day be useful for analysis of sports performance.
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    Fitting Triangular B-Splines to Functional Scattered Data
    (Blackwell Science Ltd and the Eurographics Association, 1996) Pfeifle, Ron; Seidel, Hans-Peter
    Scattered data is, by definition, irregularly spaced. Uniform surface schemes are not well adapted to the locally varying nature of such data. Conversely, Triangular B-Spline surfaces 2 are more flexible in that they can be built over arbitrary triangulations and thus can be adapted to the scattered data.This paper discusses the use of DMS spline surfaces for approximation of scattered data. A method is provided for automatically triangulating the domain containing the points and generating basis functions over this triangulation. A surface approximating the data is then found by a combination of least squares and bending energy minimization. This combination serves both to generate a smooth surface and to accommodate for gaps in the data. Examples are presented which demonstrate the eftectiveness of the technique for mathematical, geographical and other data sets.