Issue 2

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https://diglib.eg.org/handle/10.2312/73

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    Efficient Lossless Image Contour Coding
    (Blackwell Science Ltd and the Eurographics Association, 1996) Turner, Martin J.; Wiseman, Neil E.
    A process is presented for converting a raster image into a discrete set of plateaus or contours. A contour coder has been developed which fully describes these contours via their boundary descriptions in a compact and computationally efficient manner, and is the basis for an image compression method. An analysis of some of the possible edge coding schemes is presented with both theoretical and practical conclusions. Described is a detailed study of the problems encountered and solutions chosen.
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    Energy Duality Methods for Piecewise Bezier Curve Construction
    (Blackwell Science Ltd and the Eurographics Association, 1996) Bercovier, M.; Volpin, O.
    Piecewise Bezier Curves are constructed using a minimization principle. Ck and GCk continuity is imposed by linear constraints. The corresponding quadratic programming with linear constraints problem is introduced and solved by duality methods. Bordering matrices methods are implemented to deal with local refinement (subdivision). The result is a versatile tool for defining/editing contours made of piecewise Bezier curves.
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    Functions Defining Arbitrary Meshes - A Flexible Interface between Numerical Data and Visualization Routines
    (Blackwell Science Ltd and the Eurographics Association, 1996) Rumpf, Martin; Schmidt, Alfred; Siebert, Kunibert G.
    Most of the rendering tools in scientific visualization are restricted to special data structures which differ substantially from the data formats used in numerical applications. Trying to close this gap, we present an interface between data from numerical methods on general types of grids - like cuboidal, prismatic, simplicial, parametric, mixed, or hierarchical meshes - and general visualization routines. It is based on a procedural approach managing a collection of arbitrary elements and a set of functions describing each element type. No mapping of (an in general enormous amount of) numerical data onto new data structures is necessary- a user may use his own data structures and only has to provide this small set of procedures and functions. The visualization tools will then use these routines to access (temporarily and locally) data of interest, like information about a single element. Compared with display routines on a specialized data structure, this general interface does not produce much cpu overhead.
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    Incremental Line Labelling for Sketch Input of Solid Models
    (Blackwell Science Ltd and the Eurographics Association, 1996) Grimstead, I. J.; Martin, R. R.
    Designers need to transfer three-dimensional objects from their minds via a two-dimensional interface into a solid modelling system. We propose a system where objects are sketched interactively in two-dimensions and incrementally line-labelled as the drawing progresses, as the preliminary stage in constructing a solid model. Once the sketch is complete, the line-labels are coupled with various inferred constraints to enable us to generate a solid model. In this paper we describe and evaluate a modification to existing line labelling methods to allow them to work incrementally. In this way, the labelling and region information can be built up as the user sketches, rather than all at once at the end of the sketching process, which reduces the delay before the final solid model is built.
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    The Layout Design Language: A Technique for Generating Layout Plans
    (Blackwell Science Ltd and the Eurographics Association, 1996) Grimsdale, R.L.; Chang, C.W.
    The work described in this paper arose from a requirement for a system to support the production of models for training simulator visual systems and other visualisation applications. To reduce the labour involved in generating such models, it was decided to develop a technique whereby models could be generated by a high-leuel language. For these models there is a requirement to generate 2-D plans showing, for example, the locations of roads and buildings, subsequently 3-D models of the buildings are placed at the defined locations. The 2-D plans can be created through the use of the Layout Design Language (LD-Language). LD-Language has been formulated particularly for designing urban area street plans.The primitive elements of the LD-Language, plots, are assembled into patterns which can be further combined into a layout plan, with some support provided by the system. The work reported has successfully demonstrated that a complex layout plan can be developed using this language.
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    Pertinent Data for Modelling Pigmented Materials in Realistic Rendering
    (Blackwell Science Ltd and the Eurographics Association, 1996) Callet, Patrick
    This article discusses the important problem of determining pertinent data to describe a pigmented medium. The first part deals with optical characteristics of pigments and the general properties of binders and fillers. It also exposes the limits and conditions of applicability of single scattering. In the second part the connection between individual optical properties, size, and form of particles is made with phenomenological theories of multiple scattering in absorbing media, Progressively, it appears that pertinent data in realistic modelling are always in relation with true or effective complex refractive indices and size parameters.