EG1984

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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.
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.
INTERACTIVE EDITING OF POLYGONS
(The Eurographics Association, 1984) Olsson, Lennart; K. BO and H.A. TUCKER
This paper describes an internal data structure which can be used in interactive editing of polygons. A user can delete, restore, split and merge polygons and change type and direction of polygons. The polygons that are edited are segmented lists of pixels. These lists are extracted from digital images by automatic programs.
COMPUTER GRAPHICS PRODUCTION AS A BUSINESS
(The Eurographics Association, 1984) Kaneko, Mitsuru; K. BO and H.A. TUCKER
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.
IMPROVING COMPUTER GRAPHICS TOOLS FOR ARCHITECTS
(The Eurographics Association, 1984) Ekeberg, Oerjan; Engblom, Carl-Henrik; Kjelldahl, Lars; Lundequist, Jerker; Thörnblom, Ingvar; K. BO and H.A. TUCKER
During the last ten years a lot of work has been done in architectural applications using computers and especially computer graphics. It is however obvious that these new tools have not been fully accepted by architects in common. We think that one of the main reasons for this is the poor facilities for the interaction between the user and the machine. In our project at KTH in Stockholm we use modern workstations with bitmapped techniques to study the possibilities to design good interactive facilities. Ideas for interactive techniques are gathered together with architects and are implemented on a Xerox LISP machine. The most interesting and important techniques are studied in experiments that are set up together with behavioural scientists.
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.
QUADTREE SCAN CONVERSION
(The Eurographics Association, 1984) Oliver, M.A.; King, T.R.; Wiseman, N.E.; K. BO and H.A. TUCKER
An efficient method is described for turning a quadtree encoding of an image into scan lines. When implemented in hardware it becomes possible to generate video in real time for a raster display without the need for a conventional frame buffer. This suggests that a new form of display processor could be constructed that operates on coded images instead of rasters and (from previous work) that useful speed improvements might then obtain for certain operations.
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.
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.
SHAPING THE FUTURE A SYSTEMS APPROACH TO MIS PLANNING
(The Eurographics Association, 1984) Kirkley, John L.; K. BO and H.A. TUCKER
RAY TRACING OBJECTS DEFINED BY SWEEPING A SPHERE
(The Eurographics Association, 1984) Wijk, J.J. van; K. BO and H.A. TUCKER
The basic calculation underlying ray tracing is that of the intersection of a line with the surfaces of an object. A method is presented here for performing this calculation for a new and powerful class of objects, those defined by sweeping a sphere of varying radius along a 3D trajectory. When polynomials are used for the parametrization of the centre and radius of the sphere, the intersection problem reduces to the location of the roots of a polynomial. An implementation is presented, together with sample applications.
Twixt: A 3D Animation System
(The Eurographics Association, 1984) Gomez, Julian E.; K. BO and H.A. TUCKER
This paper describes a visually interactive 3D computer animation system. Animation is controlled by lists of events stored in tracks. Tracks are interpolated by functions that have an arbitrary degree of knowledge about how to control display parameters. The system provides real time wireframe playback so the animator can see what the animation looks like and is both input and output device independent.
Three-Dimensional Data Input by Selection of Hierarchically Defined Blocks
(The Eurographics Association, 1984) Yamaguchi, K.; Inamoto, N.; Kunii, H. S.; Kunii, T. L.; K. BO and H.A. TUCKER
This paper discusses inputing three dimensional solid object data by means of a two dimensional tablet. This method involves refining an object by gradually generalizing a class of 'permissible' objects. The design of an object is first limited to an octree, which is a set of cubes. At this step, a single selection can create, divide or destroy a cube. It is expected that after this rough design step has been completed, the designer can go on to the next step in which the target object is a polyhedron. The advantages of using this octree design method are: 1. the designer always has a valid three dimensional object, 2. few selections are required for generating a rough design, and 3. each displayed candidate cube serves as a menu for guiding the designer in making decisions. A technique for displaying objects and experimental designs is illustrated.
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.

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