EG1984 Proceedings (Technical Papers)

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APPLICATION OF COMPUTER-GENERATED ANIMATION IN EUROPEAN SPACE RESEARCH
(The Eurographics Association, 84) Kristiansen, E.; K. BO and H.A. TUCKER
In space research, there is often a need to illustrate motion, such as a spacecraft's orbital motion and attitude manoeuvres. This paper presents various types of applications for computer generated animation in space research. Some problem areas are discussed, such as scaling in space and time, conflicts between small and large objects, and problems of representation of slow and fast motion. Finally, a particular project is presented, together with the experience gained.
A PAINT PROGRAM FOR THE GRAPHIC ARTS IN PRINTING
(The Eurographics Association, 84) Willis, P J; K. BO and H.A. TUCKER
There is considerable scope for the application of computer techniques to help the graphic designer working with printed products, provided that pictures of high technical quality result. Described here is the product of the first stage of a research programme aimed at providing computer assisted drawing aids for high quality colour pictures. The product is an interactive paint program. The paper first explains the nature of the application and the hardware available to the author. It then claims that transcription is central to the task of high quality painting. Next there is a description of the facilities available to the interactive user. Finally, a case study of the implementation of one particular command is used to illustrate the general design of the program and to illustrate why this results in a less rigid interaction than in conventional paint programs.
CONVENTIONAL ELEMENTS OF ENGINEERING DRAWINGS - FREE FORM CURVES
(The Eurographics Association, 1984) Renner, G.; K. BO and H.A. TUCKER
Technical objects which are typically described by free-form surfaces, usually also contain conventional elements (planes, cylinders, cones). Consequently, methods and systems for defining free-form shapes are advantageously complemented by description of simple geometrical elements. In the paper, known methods of computational geometry are examined from the point of view of describing curves containing straight line sections. Moreover an analysis of the accuracy of approximating a circle by these methods i s given.
CADASTRAL MAPPING PILOT PROJECT
(The Eurographics Association, 1984) Sondergaard, Aage; K. BO and H.A. TUCKER
The immense and complicated task of converting a traditional cadastral map production into the most modern computer assisted interactive graphic production technique, and at the same time achieve increased productivity, improved quality and reduced costs, was regarded as a challenge so big that it was advisable to analyse and test the prospects in a pilot project environment. The project has now revealed that all this is obtainable, and that it is possible to extend the conversion from analogue to digital maps over a considerable period of time without losing overview or control of the entire map production.
A COMPUTER GRAPHIC APPROACH TO LATERAL SKULL CEPHALOSTAT RADIOGRAPH ANALYSIS FOR ORTHODONTIC DIAGNOSIS AND TREATMENT PLANNING
(The Eurographics Association, 1984) Hubbold, R.J.; Eid, A.A.; K. BO and H.A. TUCKER
Interactive computer graphics programs have been developed to permit the clinical application of a new method of analysis of craniofacial discrepancies and its use for diagnosis and testing alternative treatment plans. The validity of the method has been tested statistically, and the programs have been used to formulate treatment plans for a number of orthodontic patients. Example results from the treatment planning are included.
TWO DISPLAY ALGORITHMS FOR OCTTREES
(The Eurographics Association, 1984) Oliver, M.A.; K. BO and H.A. TUCKER
This paper deals with the problem of the fast display of a three dimensional object that is represented by an Octtree with the Octtree encoded as a simple linear structure without pointers. Two algorithms are described: the first allows a plane section through an Octtree image to be displayed and the second is for the orthographic projection of an Octtree. In the latter algorithm only trivial modifications are needed in order to depth cue. In both algorithms the display image is generated in the form of a quadtree.
EXPERIENCES WITH NEW IMAGE COMPONENT ALGORITHMS
(The Eurographics Association, 1984) Samet, Hanan; Tamminen, Markku; K. BO and H.A. TUCKER
We present experiences and comparisons evaluating a fast algorithm for connected component labeling of quad- and octrees. The algorithm works without loss of efficiency on linear tree representations that may reside in external storage.
BILEVEL DISPLAY SCREEN PRESENTATION OF TEXT, GRAPHICS AND IMAGES FOR PAGE MAKE-UP WORK
(The Eurographics Association, 1984) Sundblad, Yngve; K. BO and H.A. TUCKER
Limitations in resolution of bilevel display screens and processing power of processors call for special considerations in the design of computerised tools for make-up of document and newspaper pages. Here we discuss and illustrate various such considerations for presentation of text with typography, graphics and continuous tone images.
A TWO-DIMENSIONAL CLIPPING DIVIDER
(The Eurographics Association, 1984) MERIAUX, Michel; K. BO and H.A. TUCKER
The clipping problem is the heart of a lot of algorithms to produce computer generated images. Sutherland and Hodgman proposed a reentrant clipping algorithm ; we propose here two solutions to achieve a true two-dimensional line clipping and we apply them to convex polygon clipping. Performance evaluation shows that this parallel solution is much more interesting than the classical sequential one.
SUDS - SUrface Description System
(The Eurographics Association, 1984) Moretonl, Henry P.; Bergeron, R. Daniel; K. BO and H.A. TUCKER
A library of routines has been developed for the design of arbitrarily curved three-dimensional surfaces. The routines provide for the description and editing of surfaces. Surfaces are defined by families of parametric curves which are blended, using linear interpolation, approximating splines or interpolating splines. Each component curve is in turn defined by a set of ordered control points which are blended using any of these techniques. This approach affords greater flexibility than more classical methods such as bi-variate patches. The editing facilities include the basic spatial transforms as well as a full complement of attribute setting functions.
THE COMPUTER GRAPHICS SCENE IN THE UNITED STATES
(The Eurographics Association, 1984) Badler, Norman I.; Carlbom, Ingrid; K. BO and H.A. TUCKER
We briefly survey the major thrusts of computer graphics activities, examining trends and topics rather than offering a comprehensive survey of all that is happening. The directions of professional activities, hardware, software, and algorithms are outlined. Within hardware we examine workstations, personal graphics systems, high performance systems, and low level VLSI chips; within software, standards and interactive system design; within algorithms, visible surface rendering and shading, three-dimensional modeling techniques, and animation.
GRAPHICAL SUPPORT IN A USER INTERFACE MANAGEMENT SYSTEM
(The Eurographics Association, 1984) Guest, Steve; Edmonds, Ernest; K. BO and H.A. TUCKER
SYNICS2 is a User Interface Management System (UIMS) using the concept of Recursive Transition Networks (RTN) for its control structure. It is used as an intelligence terminal would be, being situated between the computer application program and the end user's interface device. It controls the hardware device and allows the application to be relatively free from hardware dependent coding. The result is that the application interface model can be simplified and allow the user interface to be tailored to a standard so that all applications have a uniform view. Generated graphical output is based on the Graphical Kernel System (GKS). This paper is concerned with the facilities in SYNICS2 for the use of graphical input and output.
HOW INTELLIGENT CAN BUSINESS GRAPHICS SOFTWARE BE?
(The Eurographics Association, 1984) Jones, Peter R.; K. BO and H.A. TUCKER
This paper justifies the question posed in its title, by pointing out some of the reasons which make the use of a "quasi" automatic system necessary, when customized performances of the intelligence built in a business graphics package are desired. The implementation case reports on experience gained from coding a Pascal package for a 16-bit Zilog 8000 machine, hosting Olivetti's proprietary Multifunctional Operating System (MOS).
USER INTERFACE: CONCEPTS AND SPECIFICATIONS
(The Eurographics Association, 1984) Spliid, Axel Monrad; Sorgen, Amos; K. BO and H.A. TUCKER
A CAD/CAM/CAE system may be very powerful, but its acceptance among a user group depends heavily on its User Interface. It is very important that the User Interface of such a system can easily be adapted to the engineer's way of thinking and working. This paper presents the results of the development made at the Control Engineering Section of the Institute for Product Development at the Technical University of Denmark, in order to reach this goal. Modules which can easily be assembled to fulfil differentuser requirements for interaction with the system were developed. The basic building blocks in the input process - like a key stroke on the key board or a light pen interrupt - are hierarchicallycomposed into tokens and higher syntax constructs. Five basic processes are present at each level in the hierarchy: Prompting, echoing, input interpretation, information transmission to a higher level and error handling. Care was taken to clearly identify different interface levels to device dependent features, leaving the User Interface itself device independent.
STEPS TO EFFECTIVE BUSINESS GRAPHICS
(The Eurographics Association, 1984) Macllroy, AI; Wyman, Peggy; K. BO and H.A. TUCKER
THE DEVELOPMENT OF COMPUTER GRAPHICS CURRICULA FOR DESIGN EDUCATION
(The Eurographics Association, 1984) King, Robin G.; K. BO and H.A. TUCKER
With the imminent availability of low cost, high resolution computer graphics systems suitable for visual and graphic arts applications, design education must now come to terms with radical changes in design methodology and stylistic content. This paper explores some of the more critical problems facing design educators and in particular those which will force significant departures from current curricula. A case study is explored and recommendations given for program design and new teaching strategies.
A NEW DISPLAY FILE STRUCTURE FOR LINE AND SURFACE PRESENTATIONS
(The Eurographics Association, 1984) Krmer, Thomas; Rix, Joachim; K. BO and H.A. TUCKER
In the design process of 3D objects i t will be helpful to use not only an output pipeline design for a wire frame model on a vector device but also for shaded surface presentations on a raster device. To reduce the total amount of computations for B-spline defined objects, a common display file is proposed, that allows a fast interpretation for both representations. Also i t supports fast previewing techniques and interaction. All B-spline computations are calculated only once in a device independent way before i t is stored in that display file.
NUMERICAL SIMULATION AND VIDEO DISPLAY OF DYNAMIC PROBLEMS
(The Eurographics Association, 1984) Janick, CARNET; Jacques, DUJARDIN; K. BO and H.A. TUCKER
The increasing ability of computers to digest and regurgitate numerical results requires graphic displays which allow new and complex problems to be dealt with. In this paper we present software designed to study phenomena modelled by partial differential equations. The numerical solution is obtained by the finite element method which has two parts, namely region meshing and discrete equation solving. The simulation results are then displayed on a video screen.
THE DESIGN OF A USER INTERFACE FOR A CAM APPLICATION
(The Eurographics Association, 1984) Sauter, Roland; K. BO and H.A. TUCKER
This paper describes a user interface which has been designed for the rough environment of a workshop floor. It has a strictly hierarchical structure of the commands, but allows a lot of context-free operator's actions and enquiries, which can be activated at any time through the use of universal commands. The user can walk up and down in the dialog, can look at any available data or command, or at the history; he can even look at the user's manual on the screen.
COMPUTER GRAPHICS FOR VISUALIZING SIMULATION RESULTS
(The Eurographics Association, 1984) NAKAMAE, Eihachiro; YAMASHITA, Hideo; NISHITA, Tomoyuki; K. BO and H.A. TUCKER
Computer graphics techniques for visualizing the following simulation results are developed: (1) lighting designs for different type sources such as point sources, linear sources, area sources, and polyhedron sources, (2) shaded time at arbitrary positions such as windows, walls, and even the inside of a room, (3) montages for view environment evaluation, (4) quasi-semi-transparent models for observing life generation process in anatomy, and (5) two and three dimensional magnetic fields analyzed by the finite element method.

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