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Item Evaluation of Standard Graphics Packages(Blackwell Publishing Ltd and the Eurographics Association, 1987) Klok, FopkeIn order to compare the quality of different implementations of GKS, the ISO0 standard for computer graphics, an evaluation method for GKS implementations is presented. It is based upon several groups of criteria. One group of criteria is concerned with performance, by which we understand here the memory requirements and time requirements for programs using GKS functions. A program that measures the performance of GKS packages is presented. Results of this evaluation method with several commercially available GKS implementations are described in summary. A checklist for evaluation of standard graphics packages is added as an appendix.Item A Means to Improve the GKS-3D/PHIGS Output Pipeline Implementation(Eurographics Association, 1987) Herman, Ivan; Reviczky, JanosThe output pipeline of GKS-3D/PHIGS isexamined to find some possible points where the implementation could be improved to raise efficiency while remaining strictly within the scope of the Standards. Some interesting results are presented in the paper which have led to a 25-30% improvement in speed when compared to a more conservative implementation.Item Display of Solid Models with a Multi-Processor System(Eurographics Association, 1987) Jansen, Frederik W.; Sutherland, Robert J.There is a growing need for fast high-quality display of solid objects. Recently-developed custom-VLSI hardware offers high-speed display but lacks the flexibility and processing power at the pixel level to sustain the calculations and filter operations needed for realistic reflection models, texture mapping and anti-aliasing. Multi-processor systems built with general-purpose components of relatively high capacity and moderate cost provide an alternative; they also offer higher performance than single processor systems but retain their flexibility. A CSG hidden-surface algorithm based on depth-buffering and image subdivision is presented which is suitable for use with such a multi-processor system.Item A New Algorithm of Space Tracing Using a CSG Model(Eurographics Association, 1987) Bouatouch, Kadi; Madani, M.O.; Priol, Thierry; Arnaldi, BrunoThis paper describes a new algorithm of space tracing. Scenes are modeled by a CSG tree. Space is subdivided regularly into 3D regions called boxes. With each box is associated a subtree which is the restriction of the whole scene CSG tree to primitives belonging to this box. A 3D grid is used to access boxes.Item A New Scan Line Algorithm for the Rendering of CGS Trees(Eurographics Association, 1987) Pueyo, Xavier; Mendoza, Joan CarlesA scan line algorithm is proposed to render CSG modelled solids. Scan planes intersections are obtained by means of a proposed generalisation of Porter’s algorithm. 2-D scan plane primitives are decomposed in a way that provides a more accurate disjointness information then 3-D inclosing boxes and a simple way to class spans. Furtheremore, this scan plane organisation allows the use of most of scan line hidden surface strategies that make use of different types of coherence to speed up the visibility process.Item An Intersecting Modification to the Bresenham Algorithm(Blackwell Publishing Ltd and the Eurographics Association, 1987) Skala, ViclavItem Call for participation(Blackwell Publishing Ltd and the Eurographics Association, 1987)Item Generative Scene Modelling(Eurographics Association, 1987) Beyer, Thomas; Friedell, MarkWe describe a new theory of scene modelling that includes generative processes as integral components of scene descriptions. A single, uniform treatment of generative processes replaces the variety of ad hoc mechanisms commonly in use. We discuss the implementation of the theory in an experimental modelling system and show that L-systems, fractals, and particle systems, as well as many specialized generative processes, become comparatively easy to define and use.Item Making Drawings Talk: Pictures in Minds and Machines(Blackwell Publishing Ltd and the Eurographics Association, 1987) Bijl, AartInteractions between human minds and machine systems will be discussed, drawing on experience of CAD and focusing on modes of expression. Free forms of text and drawings pose deep questions when interpretations have to be"meaningful" to different knowledge representations - especially in loosely defined application fields. What should we expect from technology?Item Inaugural Meeting of the EUROGRAPMCS Spanish Chapter(Blackwell Publishing Ltd and the Eurographics Association, 1987) Duce, D A