EG1986

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    Multi-Dimensional Graphics: Algorithms & Applications
    (The Eurographics Association, 1986) Inselberg, Alfred; A.A.G. Requicha
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    An Introduction to the Graphics Systems Processor
    (The Eurographics Association, 1986) Short, Graham; A.A.G. Requicha
    This paper describes the system applications of the Graphics System Processor (GSP) produced by Texas Instruments Inc. The paper discusses the general-purpose capabilities of the GSP which make it a flexible processor to use. It then goes on to show how the graphics-specific parts of the GSP make it a powerful tool, ideally suited to graphics applications. Finally the paper discusses some of the programmable hardware functions of the GSP which make it easy to design into any graphics system.
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    An Implementation of the GKS-3D/Phigs Viewing Pipeline
    (The Eurographics Association, 1986) Singleton, Karen; A.A.G. Requicha
    Following the establishment of GKS as the first international standard for computer graphics, two new standards, GKS-3D and PHIGS, are emerging which cater for three dimensional graphics. In order to display a 3-D object, a description of how it is to be viewed must be given. GKS-3D and PHIGS provide a viewing pipeline to generate the parallel or perspective view required. This paper describes in detail the functionality and an implementation of the GKS-3D/PHIGS viewing pipeline.
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    A Quad-Tree Algorithm for Displaying a 2-Dimensional Slice of an N-Dimensional Weighted Voronoi Tessellation
    (The Eurographics Association, 1986) Angell, Ian O.; Moore, Richard E.M.; A.A.G. Requicha
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    A Statistical Method For Adaptive Stochastic Sampling
    (The Eurographics Association, 1986) Purgathofer, Werner; A.A.G. Requicha
    Stochastic sampling is a good alternative to pure oversampling in terms of image quality. A method for adaptively controlling the number of required samples to the complexity of the picture is presented. The quality of the obtained picture can be controlled by two well-understandable parameters, these parameters define an error interval sire and the probability that a pixel lies within it. The usefulness of the method is described by applying it to distributed ray-tracing.
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    A General Purpose User Interface With Hierarchical Data Structure Management
    (The Eurographics Association, 1986) Janni, Alberto Di; Italiano, Margherita; A.A.G. Requicha
    This paper presents a general purpose User Interface Management System based upon a user driven menu handling and a hierarchical organization of graphic data structure. The package has mainly two purposes: one being to provide facilities to the application programmer in order to ease their tasks and the other one bei to provide a uniform enviroment to the final user. It fulfills two different tasks: it realizes the dialogue with the user and offers a complete set of high level procedures to manage graphic data. lauded attributes, like device independence, feedback at both syntactic and semantic levels, internal automatic recovery, style independent interface toward the application, management and hierarchical definition of structured graphic output, high level graphic functions and a simple definition language. Moreover this system is particularly intended to cover requirements of tools dedicated to integrated circuit design and makes use of a few devices to cut off the computation time and to optimize the memory occupation.
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    A Multiple Application Graphics Integrated Circuit - MAGIC
    (The Eurographics Association, 1986) Agate, M.; Finch, H.R.; Garel, A.A.; Grimsdale, R.L.; Simmonds, A.C.; Lister, P. F.; A.A.G. Requicha
    MAGIC is a geometry processor which Corms a part of a graphics system based on parallel processing. The number of MAGIC processors required is dictated by the desired system performance. Each unit is capable of controlling the transformation of points and edges from the co-ordinate system of the world model into screen co-ordinates, and performing the associated clipping operations. The proposed VLSI implementation of these transformations is intended to be sufficiently flexible for additional operations such as texture mapping and ray tracing to be supported.
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    Towards the Construction of Graphical Interfaces on the Basis of Geometric Models
    (The Eurographics Association, 1986) Prospero, Manuel Joao; Messina, Luiz Ary; A.A.G. Requicha
    Dialogue control and dialogue object structures are the outlined concepts developed in this paper. Phases of a CAD-Process are presented to show an outstanding application for the concepts The use of logic programming dealing with geometric structures performs the innovative elements to enable the construction of more flexible graphical interfaces, which can operate as information collectors and structure checks in design processes.
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    A consistent algorithm to fill triangles and triangular patches
    (The Eurographics Association, 1986) Overveld, C.W.A.M. van; Lierop, M.L.P van; A.A.G. Requicha
    In this paper an algorithm is described for filling triangles in 3D. Since this algorithm uses integer arithmetic only, it is not hampered by inconsistencies that normally arise due to finite machine precision. Moreover, the same algorithm is used for both curved and flat triangular patches.
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    A Visualisation Tool for (Landscape) Architects
    (The Eurographics Association, 1986) Lankhorst, Mrs. J. Roos - Klein; A.A.G. Requicha
    In a small and crowded country such as the Netherlands both the government and the individual people are very concerned with what is happening in their environment. Apart from the ecological impacts, the visual effects of new developments are often a very important issue. In this respect a realistic visualisation of future developments can be very useful. Described here is the product of the first stage of a research programme aimed at providing visualistion aids for landcape architects and building designers. Besides showing future developments to the people involved, this tool should enable the building designer to evaluate the aesthetics of a design with respect to the surroundings. Moreover it should enable the landscape architect to "reshape" the landscape by adding, removing and editing artifacts and natural elements on the the graphics screen.
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    A Portable Graphical Display System For The Partially Sighted
    (The Eurographics Association, 1986) DUNLOP, G.R.; B.Sc.,; B.E.(Hons),; Ph.D.,; M.I.E.E.,; C.Elec.Eng.,; A.A.G. Requicha
    A portable reading aid based on a graphical display system has been developed for partially sighted persons. This graphical display system incorporates dual microprocessor control of a flat panel AC plasma display and a solid state fibre optics camera. The unique camera uses coherent fibre optics for image dissection so that a synthetic viewing aperture is generated from a single linear imaging device. The lensless camera utilises proximity focusing and switchable electronic magnification settings from 4 to 64. The graphical display produces neon orange images which are refreshed at almost 100 Hz to give bright flicker free images which are suitable for viewing either directly or with only the peripheral vision available to many partially sighted people.
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    A Multiprocessor Architecture For High-Quality Interactive Displays
    (The Eurographics Association, 1986) Sutherland, Robert J.; A.A.G. Requicha
    A multiprocessor array coupled to a deep framebuffer is proposed as the basis for an interactive user environment of high quality. Several aspects of such an architecture are considered, improvements on previous approaches are suggested, and two designs of high-performance displays based on standard LSI components are described.
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    Linked Management Graphics For Production Control
    (The Eurographics Association, 1986) Woodgate, H. Sam; A.A.G. Requicha
    This paper describes the use of Linked Graphical Displays as a means of extending the information transfer capability of Management Graphics Systems in the context of Engineering Manufacturing. As the pace and complexity of manufacturing increases, management need faster and better methods of absorbing the information contained in the large Databases used to control production. In the system described a number of different graphical displays are created from the same large Database and accessed via a "Choice Processor" to give multiple views on the situation represented by that data. The simple effectiveness of computer produced graphics as a man/machine communication media is retained but the multiple access facility enables more complex issues to be revealed and cross checked by sequentially viewing and comparing different interpretation of Data. Examples of the Charting Techniques employed are described together with an explanation of how they are created and used.
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    An Advanced Display System With Natural Interactivity
    (The Eurographics Association, 1986) Kankaanp, Arto; A.A.G. Requicha
    This paper describes an experimental display system that allows easy interaction with the graphics display. The user uses a pen-like device to draw directly on the display surface. The system is based on an electroluminescent flat panel with a resistive touch-sensitive surface. A pen with a conductive tip is used for direct drawing. For evaluation the display system is connected to a powerful microcomputer having a true bit-mapped graphics capability. The prototype software consists of a word processing program that includes integrated line graphics drawing capability. Text correction and formatting is done directly on the display using standard proof correction marks. Graphics drawing is done by sketching a figure on the screen with the pen and correcting it by software. The system is also evaluated using the Keystroke-Level Model by CARD et. al. [1] for accomplishing the basic editing tasks with a word processing application.
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    A Version Management System for Design Environments
    (The Eurographics Association, 1986) Heine, Thomas Riedel-; Köhler, Dagmar; A.A.G. Requicha
    Design environments for CAD/CAM require new techniques of version management. This work presents a concept of a largely data modelindependent version manager thus allowing easy integration into any existing database system. An implementation proposal of a version manager based on a relational database system is given.
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    Digital Synthesis Of Calligraphic Script
    (The Eurographics Association, 1986) Dooijes, E.H.; A.A.G. Requicha
    We discuss some of the problems associated with the generation of publication quality, quasi-calligraphic script from keyboard input. Our ultimate goal is the construction of a system for the production of Arabic texts, to be implemented on a microcomputer.
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    The Integration of Particle and Polygon Rendering using an A-buffer Algorithm
    (The Eurographics Association, 1986) N.Magnenat-Thalmann,; D.Thalmann,; S.Beland,; A.A.G. Requicha
    A particle system, as defined by Reeves, is a collection of particles that together represent a fuzzy object. Over a period of time, particles in the system are born, move, change and die. We have introduced interactive control of procedural models into our extensible director-oriented animation system MIRANIM. With this approach, a user may define his/her own evolution laws in particle systems. Systems may be initialized by interactive commands and are then updated by animation blocks, and the laws may return any state variables. Unlike Reeves' work, particle systems may intersect with other surface-based modeling primitives. Our rendering method is based on a scanline A-buffer algorithm, which is an extension of the processing of translucent polygons. This approach proved to be particularly useful for modelling objects destroyed by a fire with the presence of a wind.
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    Mappings Between Product Data Definitions
    (The Eurographics Association, 1986) Richter, Dieter; A.A.G. Requicha
    It can be observed that existing product data interfaces are constructed by a pragmatic manner. It is not seen any theoretical approach neither for describing nor for evaluating models. In this paper an algebraic approach based on heterogeneous algebras is presented.
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    A Pixel-Parallelhidden Surface Algorithm For Constructive Solid Geometry
    (The Eurographics Association, 1986) Jansen, Frederik W.; A.A.G. Requicha
    VLSI techniques have greatly enlarged the possibilities to design new frame buffer architectures with parallel processing capabilities down to the pixel level. For these pixel processor systems a parallel hidden surface algorithm is presented for displaying objects defined with Constructive Solid Geometry. The algorithm is based on a CSG evaluation with bitwise operations and multiple scanning of the primitives.
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    Geometric Boundary Modelling without Topological Data Structures
    (The Eurographics Association, 1986) Takala, Tapio; A.A.G. Requicha
    The Boundary Representation (BR) scheme for solid modelling is reconsidered and generalized in the paper. It is pointed out that the topological data, though usually represented separately, is derivable from the geometric data, and that there are fundamental inconsistencies between these two. The topological data structures are unnecessary or even harmful in practice as they restrict the modelling domain. New BR methodology without explicit topology is demonstrated by algorithms, which manipulate a stream of separate polygons as a solid model.