Issue 5

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https://diglib.eg.org/handle/10.2312/58

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    ANIMA: An Interactive Tool for Scientific Data Animation
    (Blackwell Science Ltd and the Eurographics Association, 1993) Moltedo, Laura; Morigi, Serena
    This paper describes an animation interactive system that produces image sequences used to study the numerical results of scientific simulations. The fundamental goal of the system is to provide an easy method for observing and exploring scientific computation during its space-time evolution. To do that it is necessary to combine simulation processes, algorithmic and key frame animation with geometric transformations, light effects and camera movements. ANIMA allows the researcher to use animation without special programming, with the aid of a graphic user interface. Modelling, rendering, motion control and synchronization of graphic objects are interactively specified by the animator in order to define an animation script. The system development methodology follows an object-oriented technique using modular programming, abstract data type definition, and graphic metaphor with user interface menus.
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    A Fractal Method for Digital Elevation Model Construction and its Application to a Mountain Region
    (Blackwell Science Ltd and the Eurographics Association, 1993) Brivio, Pietro Alessandro; Marini, Daniele
    This paper presents and discusses the results of a methodology for the construction of Digital Elevation Models (DEM), based on mathematical principles of fractal geometry. Classical approaches to DEM are founded on numerical methods of interpolation or approximation of data extracted from contour lines of standard topographic maps. Fractal geometry opens a new and innovative approach in which the irregularity, erraticity and self similarity of fractal structures mimics at best the typical behaviour of high mountain profiles. The adoption of fractal methods requires the identification of the fractal dimension D for a given data set. The determination of the fractal dimension D can be achieved applying some special mathematical method on finite set of samples. Different methods. for D estimation are presented. Once the fractal dimension is given, it is possible to reconstruct a surface relief using different fractal methods which interpolate the original set of elevation data. Our research has also investigated two different interpolation methods, fBm and IFS, both confirming that the fractal approach is very well suited for high relief terrain modeling. Photo realistic rendering of the computed DEM allows to appreciate the quality of the reconstruction through visual inspection.
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    Graphic Objects: A Mathematical Abstract Model for Computer Graphics
    (Blackwell Science Ltd and the Eurographics Association, 1993) Torres, J.C.; Clares, B.
    This paper defines an abstract mathematical model for graphic systems which incorporates modelling operations. The model is based on the"graphic object" concept. A graphic object is an abstraction of a graphic entity. Graphic objects are a generalization of the Fiume graphic object concept, supporting modelling operations, which give the set of graphic objects an algebraic structure of vector space and booelan algebra. Fiume visualization formalism can be applied to graphic objects. Further, product operations of graphic objects are defined, which are a generalization of solid sweep operations. Graphic object products may be used to build common 2D and 3D objects such as triangles, squares, cubes, circles and spheres from lines and arcs.
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    The Method of Dynamic Palette Construction in Realistic Visualization Systems
    (Blackwell Science Ltd and the Eurographics Association, 1993) Voloboj, Aleksej G.
    The paper describes the colour approximation problem and the method of dynamic palette construction is suggested for its solution. The method uses the graphic display palette based on the computed true colour of the individual picture. Some aspects of human colour perception are considered. Two metrics in colour space are introduced to estimate closeness of the suggested colour approximation. The method was applied to visualize 3D scenes generated by ray tracing.
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    A Multiprocessor Implementation of Radiosity
    (Blackwell Science Ltd and the Eurographics Association, 1993) Ng, Adelene; Slater, Mel
    This paper describes a multi-processor implementation of form factor computation in the radiosity method. Form factors are computed using the ray casting method and the algorithm is enhanced with Binary Space Partition (BSP) Trees and bounding boxes. Experimental results are presented together with a discussion of load balance efficiency.