Issue 2

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    An Implementer s View of CGM in GKS Environment
    (Blackwell Publishing Ltd and the Eurographics Association, 1987) Moltedo, L.; Noferini, A.
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    A Simple and Efficient Haloed Line Algorithm for Hidden Line Elimination
    (Blackwell Publishing Ltd and the Eurographics Association, 1987) Franklin, W.R; Akman, V.
    An efficient algorithm, HALO, is given to compute haloed line drawings of wire frame objects. Haloed line drawings are described by Appel et al.1HALO has two parts: CUT and DRAW. CUT uses an adaptive grid to find all edge intersections. It overlays a square grid, whose fineness is a function of the number and length of the edges, on the Scene. It determines the cells that each edge passes through, sorts these by cell to obtain the edges in each cell, and then, in each cell, tests each pair of edges in that cell for intersection. For broad classes of input this takes time linear in the number of edges plus the number of intersections. CUT writes a file containing all the locations where each edge is crossed in front by another. Given a halo width, DRAW reads this file edge by edge. For each edge, it subtracts and adds the halo width to each intersection to get the locations where the edge becomes invisible and visible. It sorts these along the edge, and then traverses the edge, plotting those portions where the number of"Visible" transitions is equal to the number of"invisible" transitions. DRAW takes time hear in the number of edge segments. Dividing HALO into two parts means that redrawing a plot with a different halo width is fast, since only DRAW need to be rerun.CR Categories and Subject Descriptions: I.3.5 [Computer Graphics]: Computational Geometry and Object Modeling - geometric algorithm, languages, and systems- F.2.2 [Analysis of Algorithms and Problem Complexity]: Nonnumerid Algorithms and Problems -geometrical problem and computationsGeneral Terms: Algorithms, design.
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    A Scanline Method for Solid Model Display
    (Blackwell Publishing Ltd and the Eurographics Association, 1987) Patel, Manjula; Hubbold, Roger J.
    The modelling of solid objects is becoming increasingly important in the application of computer graphics to a wide variety of problems, such as CAD/CAM, simulation, and molecular modelling. A variety of methods for rendering solid objects exists, including 2-Buffer, Scanline and Ray Tracing. This paper is concerned with a scanline method for the production of still images of complex objects. The implementation of a scanline algorithm is discussed, in conjunction with a consideration of its performance in relation to the z-buffer method.Many scanline methods cater only for a restricted class of primitives, such as polygons or spheres, whereas this implementation is a general purpose scanline algorithm capable of being extended to handle a variety of primitives. The primitives currently available are polygons, spheres, spheres swept along straight-line trajectories, and cylinders. Polygonal models of cubes, cones and cylinders are also available.The approach is capable of dealing with"positive" and"negative" volumes, allowing objects with holes to be modelled and displayed. It has further been extended to cater for the inclusion of transparent objects into a scene, and consequently allows the modelling of coloured"glass" objects.
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    Scan Converting Extruded Lines at Ultra High Definition
    (Blackwell Publishing Ltd and the Eurographics Association, 1987) Willis, Philip; Watters, Geoff
    We consider the problem of generating freehand raster graphics pictures at ultra high definition (typically one gigapixel per picture) by scan converting extruded lines. We describe a fast scan conversion algorithm which is linear in final resolution and which incorporates a number of features to ensure high efficiency. Sample pictures and corresponding performance figures are included.
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    Calendar of Events
    (Blackwell Publishing Ltd and the Eurographics Association, 1987)
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    Welcome to EUROGRAPHICS 87
    (Blackwell Publishing Ltd and the Eurographics Association, 1987)
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    Graphics in Reservoir Simulation
    (Blackwell Publishing Ltd and the Eurographics Association, 1987) Watkins, Howard K.
    Reservoir Simulation is used to manage underground oil reservoirs, and the potential cost savings associated with increased oil recovery are enormous. Because of the mathematical complexity of simulation it is necessary to use graphics to view the results. Graphics programs in this environment must be easy to use, and capable of producing images on a variety of machines and graphical devices. The paper looks at some of the problems involved.
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    UltraPaint: A New Approach to a Painting System
    (Blackwell Publishing Ltd and the Eurographics Association, 1987) Watters, Geoff; Willis, Philip
    The ideas underlying a Painting System being developed at the University of Bath are introduced. This differs from a conventional system in that ultra high definition pictures of upto 1 gigabyte may be created. We discuss approaches to implementing a number of standard paint program utilities in a form suited to our high definition method. Finally, we describe an algorithm for the rapid extrusion of brush strokes on a raster device.
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    Using Abstract Data Types To Define Large-scale World Models For Image Generation Systems
    (Blackwell Publishing Ltd and the Eurographics Association, 1987) Marsh, S.C.; Grimsdale, R.L.
    The creation of databases for real-time image generation systems is expensive and time consuming. This is mostly due to the method of defining the world models which can currently represent an area of up to 500,000 sq Km. This paper suggests that abstract data types can decline the necessary elements of world models. A programming language containing these data types can then be used to specify the construction of world models, and greatly reduce the time taken to create the databases.
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    Offers to EUROGRAPHICS Members
    (Blackwell Publishing Ltd and the Eurographics Association, 1987)
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    Computer Graphics Metafile Open Systems Opportunity Study
    (Blackwell Publishing Ltd and the Eurographics Association, 1987)
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    EUROGRAPHICS Membership Application Forms
    (Blackwell Publishing Ltd and the Eurographics Association, 1987)
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    THE CGM - A METAFILE FOR GKS?
    (Blackwell Publishing Ltd and the Eurographics Association, 1987) Brodlie, Ken; Henderson, Lofton; Mumford, Anne
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    EDITORIAL
    (Blackwell Publishing Ltd and the Eurographics Association, 1987) Arnold, David
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    Graphical Interaction Management
    (Blackwell Publishing Ltd and the Eurographics Association, 1987) Barn, Balbir S.; Willis, Philip
    Graphical interfaces and interactive graphical programmes are awkward to write because of a lack of top-down structure. A methodology for constructing graphical programs will be described, together with a system that generates the basic interaction requirements for such applications.
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    An Experiment in Algorithm Animation using SMALLTALK on a Macintosh
    (Blackwell Publishing Ltd and the Eurographics Association, 1987) Mohamed, Ramzan