Issue 2
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Item Calendar of Events(Blackwell Publishing Ltd and the Eurographics Association, 1990)Item COMPUTER GRAPHICS PROFESSIONALS(Blackwell Publishing Ltd and the Eurographics Association, 1990)Item EDITORIAL(Blackwell Publishing Ltd and the Eurographics Association, 1990) Arnold, David; Ruiter, Behr deItem EG Call for Participation in the Eurographics Working Group on Relationships betwee image Synthesis and Analysis(Blackwell Publishing Ltd and the Eurographics Association, 1990)Item Errata(Blackwell Publishing Ltd and the Eurographics Association, 1990) Herman, I.; Reviczky, J.Item Graphics Object Management in The X Window System(Blackwell Publishing Ltd and the Eurographics Association, 1990) Davison, Allan; Slater, Mel; Smith, MarkThis paper describes a library for the creation and manipulation of geometrically defined graphical objects in The X Window System Objects are arranged in a 2.5D space, and can be transformed, made invisible or visible, or have their priority changed. Transformation of objects occurs immediately and with full damage repair, thus providing an essential requirement for the support of interactive graphics. The paper reports on an experimental implementation of the library and also discusses the implications of graphical objects in the X environment.Item IFSs and Interactive Image Synthesis(Blackwell Publishing Ltd and the Eurographics Association, 1990) Horn, Alastair N.Deterministic Fractal geometry provides a framework for describing both the geometry of man-made structures and the geometry of nature.Certain deterministic Fractals which exist in the plane may be"partitioned" into a number of"tiles" equivalent to the whole under some geometric mapping. We term such Fractals self-tiling images.We describe a scheme called Iterated Function Systems (IFSs) which an represent self-tiling images. IFSs make explicit the mappings which take a self-tiling image into its tiles.We show how a self-tiling image exists as the limit of both random and deterministic processes based upon its associated IFS, and exploit massive SIMD parallelism in image generation on the AMT DAP.We also attempt to answer the question:"Can one synthesise images by the interactive graphical manipulation of a representation of IFSs?", and present our interactive system for image synthesis (ISIS).Item Modelling Clip: Some More Results(Blackwell Publishing Ltd and the Eurographics Association, 1990) Hubl, Josef; Herman, IvanThe modedling clip of the PHIGS ISO Standard is mathematically analysed. The most important result of this analysis is the fact that the projective image of a modding clip body (that is a not necessarily bounded convex body in space) is simply the union of two convex bodies. Furthermore, it will also be proved that in some cases one of these two bodies is empty. This fact makes the implementation of the modelling clip fairly straightforward and makes it also possible to use all already existing results on clipping against general convex bodies without change.Item Offers to EUROGRAPHICS Members(Blackwell Publishing Ltd and the Eurographics Association, 1990)Item A Prolog Rule-Based System for cartographic Name Placement(Blackwell Publishing Ltd and the Eurographics Association, 1990) Cook, Anthony C.; Jones, Christopher B.Manual name placement is an extremely time consuming task and has been one of the most difficult aspects of the map production process to automate. It is complicated by the large number of rules required for the selection and placement of names. A hybrid Prolog/Fortrau rule-based system is described for placing names on a variety of map types. It uses a set of Prolog primitives for spatial search and name placement operations. The Ordnance Surveyâ s 1:625000 scale digital dataset has been used to illustrate the application of rules for the selection of labels as well as for controlling their size and orientation. The application to other types of maps and diagrams is also briefly described.Item Relationships between Image Synthesis and Analysis Towards Unification?(Blackwell Publishing Ltd and the Eurographics Association, 1990) Pun, Thierry; Blake, EdwinImage analysis and image synthesis have evolved on separate tracks, at different paces. There is however an increasing awareness of the numerous and growing overlaps between the two fields. By detailing the various areas where such overlaps might be found this report wishes to promote unification of analysis and synthesis into"imagery".Three ways of looking for common ground are presented: common theoretical background, common areas of study, and common applications. They show that the distinction between image synthesis and image analysis has outlived its usefulness. The absolute differences can be discarded- what remains is a great commonality of interest.Item Top Draw: A Structure Network Visualiser for PHIGS(Blackwell Publishing Ltd and the Eurographics Association, 1990) Howard, T.W.The Programmerâ s Hierarchical Interactive Graphics System (PHIGS) is an International Standard for computer graphics. PHIGS provides a flexible mechanism for creating hierarchical models from collections of directed acyclic graphs known as â structure networksâ . In practice, the combination of powerful data structuring facilities and the ability to dynamically edit structure networks can lead to a potential complexity which makes models difficult to manage and maintain reliably.This paper presents TopDraw, a portable programming tool for visualising PHIGS structure networks, by automatically documenting their topology using diagrams. Drawing tidy representations of graphs algorithmically is a difficult problem, and most existing systems are large, complex and speciallsed The alternative approach taken in TopDraw is to use a fast, straightforward algorithm supplemented when necessary by an interactive â tidief. A novel feature of TopDraw is that the diagrams it produces are themselves PHIGS structures, which the application may edit and manipdate as required. TopDraw is a component of the PHIGS Toolkit, an emerging set of portable integrated tools for PHIGS environments.Item Workshop Report Curves for Computer Graphics Standards(Blackwell Publishing Ltd and the Eurographics Association, 1990) Hewitt, W.T.