DSpace Repository :: Browsing Volume 03 (1984) by Title

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An Algorithm for Constructing a Quadtree from Polygonal Regions

(Blackwell Publishing Ltd and the Eurographics Association, 1984) Casciani, T.; Falcidieno, B.; Fasciolo, G.; Pienovi, C.

Quadtrees are a class of hierarchical data structures particularly suitable for the representation of images in a compact form. In this paper a new algorithm is described which builds up the quadtree corresponding to polygonal multiply connected regions starting from their boundary representation.

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An Algorithm for Determining the Intersection of Two Simple Polyhedra

(Blackwell Publishing Ltd and the Eurographics Association, 1984) Szilvasi-Nagy, M.

An algorithm is presented for the construction of the intersection of two simple possibly non-convex polyhedra. The methods of descriptive geometry are applied, so that this three-dimensional problem can be solved in two dimensions.We have to find all intersections of the edges of each polyhedron with the faces of the other, and these points of intersection can be found in Monge’s model. Projecting both polyhedra on the xy and on the xz coordinate planes we obtain two superimposed maps in both projections. The algorithm to find the intersection of two maps is based upon the Shamos-Hoey, the Bentley-Ottmann and the Nievergelt-Preparata algorithms. The asymptotic time requirement for determining the polygon of intersection of two polyhedra is O((N + S)log N), where N is the sum of the numbers of vertices of the two polyhedra and S is the total number of intersections of all projected edges in the xy-plane (S = O(N2)).

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Applications of Computer Graphics in Molecular Biology

(Blackwell Publishing Ltd and the Eurographics Association, 1984) Diamond, R

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Book Reviews

(Blackwell Publishing Ltd and the Eurographics Association, 1984)

Book reviewed in this article:The Computer Image: Applications of Computer Graphics by Donald Greenburg, Aaron Marcus, Allan H. Schmidt and Vernon Goiter.Fundamentals of Interactive Computer Graphics, by J. Foley and A. van Dam, Addison-Wesley 1983

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Book Reviews

(Blackwell Publishing Ltd and the Eurographics Association, 1984)

Book reviewed in this article:Introduction to the Graphical Kernel System (GKS), F.R.A.Elementary Computer Graphics, A.A.SMALLTALK 80: Bits of History, Words of Advice Edited by Glen Krasner, Xerox PARC.

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CAD For Intelligent Activity of an Autonomous Submersible System

(Blackwell Publishing Ltd and the Eurographics Association, 1984) Russell, G T; Lane, D M

This paper describes a CAD facility for the design of automatic guidance and control strategies for an unmanned autonomous submersible. The facility utilises a three dimensional colour graphics display of the scene and vehicle trajectory, providing a man/ machine interface for the operator in addition to vehicle motion simulation with six degrees of freedom. A primary application envisaged for the CAD facility is in the design of scene analysis algorithms and the intelligent control system structure, for an autonomous submersible employing scanning sonar as its target sensor.

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Calendar of Events

(Blackwell Publishing Ltd and the Eurographics Association, 1984)

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Calendar of Events

(Blackwell Publishing Ltd and the Eurographics Association, 1984)

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Calendar of Events

(Blackwell Publishing Ltd and the Eurographics Association, 1984)

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Change of Chief Editor

(Blackwell Publishing Ltd and the Eurographics Association, 1984) Duce, David

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Colour Gradation, Shading and Texture Using a Limited Terminal

(Blackwell Publishing Ltd and the Eurographics Association, 1984) Magnetat-Thalmann, N; Chourot, N; Thalmann, D

This paper presents a method of colouring pictures by using three kinds of gradation techniques: gradation from a figure to a point, gradation from a figure to a line segment and gradation from a figure to another figure. Intermediate figures are computed by homothesis or interpolation. The gradation is obtained by colouring these intermediate figures. The colours are simulated by using programmed pattern. This approach has allowed us to produce realistic images with a hardware device that is not very good for these types of applications. because of its restricted intensity and colour capabilities. Colour distribution algorithms and gradation techniques are explained in detail. A few examples with shading and texture are shown.

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Colour Graphics and te Fifth Generation Workstation

(Blackwell Publishing Ltd and the Eurographics Association, 1984) Willis, P J

If we accept the above idiosyncratic views, what kind of architecture will the fifth generation machine offer to graphics users? We would hope to see high quality colour raster graphics, tightly coupled to a sophisticated processor but in its own address space. It should allow for pictures much larger than the screen and also at higher resolution. The local disk must be organized to handle the large amounts of data which picture manipulation on this scale calls for. Disk and main memory must have support for manipulation of two dimensional arrays of pixel data and the filing system and its utilities must reflect this. Response is more important than ever.The software to be built on to this hardware is still a matter for conjecture and depends on whether a particular combination of hardware and language family can be packaged to give clear performance advantages. However a real-time style operating system is essential.Timescales for suitable architectures seem quite short, around two or three years, with software developing beyond that. Certainly such a machine will contain far more graphical software in the operating system than any before and ought to satisfy a wide range of raster graphics applications.