EG1984 Proceedings (Technical Papers)

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AN ANALYTICAL VISIBILITY METHOD FOR DISPLAYING PARAMETRICALLY DEFINED SURFACES
(The Eurographics Association, 1984) Rehwald, Peter; Hornung, Christoph; K. BO and H.A. TUCKER
This paper describes an analytical method to determine the visible parts of a Cartesian product surface. The bounds of these visible areas are determined in terms of the (u,v)-parameter-plane. This leads to many advantages over approximating algorithms. The new method allows the calculation and display of only the boundaries and contour curves with high precision. It calculates the critical points of a surface (contours, overlapping contours, penetrations) with machine precision, independent of the resolution of the output device and makes the parallel output on vector- and raster-devices possible. The results of this method are invarying under image-transformations.
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.
AN APPROACH TO THE DESIGN OF HARDWARE CURVE GENERATORS FOR GRAPHIC DISPLAYS
(The Eurographics Association, 1984) Alia, G.; Martinelli, E.; Tani, N.; K. BO and H.A. TUCKER
Special devices to generate curves are more and more convenient because of ever growing performance graphic tools are requested for. In this paper an approach to the design of fast hardware curve generators is proposed, mainly based on the use of vector generators and of stored tables. The needed precision can be achieved, while the final point and a selected subset of intermediate points are reached with an error of half a pixel at most; output rate is very close to available vector generators rate. Our method was applied to circle generation: for radius values up to some thousands of pixels, single-chip implementation results feasible. The method is easily extensible to threedimensional curves.
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.
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.
COMPUTER GRAPHICS DEVELOPMENT IN EUROPE
(The Eurographics Association, 1984) Marechal, Guy; Matthys, Jan; K. BO and H.A. TUCKER
Europe is becoming aware that a political determination to collaborate is required, if it wants to attain the position it could claim on the basis of its research achievements. This is especially true in the field of Computer Graphics. The program ESPRIT is hopefully a decisive step in this direction.
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.
COMPUTER GRAPHICS PRODUCTION AS A BUSINESS
(The Eurographics Association, 1984) Kaneko, Mitsuru; K. BO and H.A. TUCKER
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.
COMPUTER-AIDED THREE-DIMENSIONAL RECONSTRUCTION FROM SERIAL SECTIONS: A SOFTWARE PACKAGE FOR RECONSTRUCTION AND SELECTIVE IMAGE GENERATION FOR COMPLEX TOPOLOGIES
(The Eurographics Association, 1984) Huijsmans, D. P.; Lamers, W. H.; Los, J. A.; Smith, J.; Strackee, J.; K. BO and H.A. TUCKER
To extend computer-aided three-dimensional reconstruction of (microscopic) biological structures to complex topologies, a number of specially developed contour algorithms are employed to generate hidden-line displays of user-specified selections from a dual-access relational database. The database consists of piles of automatically aligned contours from either handtraced or automatically detected surface boundaries in a series of parallel cross-sections that result from the slicing of an embedded, stained biologic structure with alignment references. A video-tape with animation sequences generated with this package will be shown during the conference.
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.
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.
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.
DIRECT CADD DRAWING (A Flexible Screen Oriented user interface to CADD)
(The Eurographics Association, 1984) Hudson, Fred W.; Jr.,; K. BO and H.A. TUCKER
Computer aided design/drafting (CADD) system developers are taking advantage of the latest developments in personal computing and human factors research by including icon (picture) driven, direct manipulation menus in a Drafting Workstation (DW). This paper describes the menus, the drafting context which they create and ways this should affect the software and hardware architecture of a DW. The software for creating the human interface, the facility for building custom menus and icons and the ways these provide access to the built-in features of the DW are described.
DRAWING OF AN UNUSUAL KIND OF DIAGRAMS - NOMOGRAM DRAWING
(The Eurographics Association, 1984) Kjelldahl, Lars; K. BO and H.A. TUCKER
Diagram drawing has traditionally been a major part of computer graphics applications. During the last few years we have seen new trends in this area. The quality of diagram drawing has increased and diagrams has been used in new applications (e.g. business graphics). In this paper we focus on another trend in computerized diagram drawing, i.e. drawing of unusual kinds of diagram. We describe a special kind of diagrams - nomograms. A system for nomogram drawing has been implemented and problem solved in that implementation are described.
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.
GENERATING HIGH QUALITY PICTURES BY RAY-TRACING
(The Eurographics Association, 1984) BOUVILLE, C.; DUBOIS, J.L.; MARCHAL, I.; K. BO and H.A. TUCKER
Ray-casting techniques provide a very general framework in which many problems can be solved in a much easier way than with conventional methods. This is particularly true for the illumination model when a high level of realism is required. Another interesting feature of ray-casting is its ability to display a wide class of algebraic surfaces with a minimum of approximations. Both aspects are developped in this paper where a full lighting model, based on a theoritical approach, is presented. Then, an algorithm for the display of surfaces of revolution is described.
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).

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