EG1984 Proceedings (Technical Papers)
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COMPUTER-AIDED THREE-DIMENSIONAL RECONSTRUCTION FROM SERIAL SECTIONS: A SOFTWARE PACKAGE FOR RECONSTRUCTION AND SELECTIVE IMAGE GENERATION FOR COMPLEX TOPOLOGIES
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Huijsmans, D. P.
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Lamers, W. H.
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Los, J. A.
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Smith, J.
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Strackee, J.
A NEW DISPLAY FILE STRUCTURE FOR LINE AND SURFACE PRESENTATIONS
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Krmer, Thomas
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Rix, Joachim
APPLICATION OF COMPUTER-GENERATED ANIMATION IN EUROPEAN SPACE RESEARCH
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Kristiansen, E.
AN ANALYTICAL VISIBILITY METHOD FOR DISPLAYING PARAMETRICALLY DEFINED SURFACES
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Rehwald, Peter
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Hornung, Christoph
Three-Dimensional Data Input by Selection of Hierarchically Defined Blocks
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Yamaguchi, K.
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Inamoto, N.
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Kunii, H. S.
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Kunii, T. L.
A COMPUTER GRAPHIC APPROACH TO LATERAL SKULL CEPHALOSTAT RADIOGRAPH ANALYSIS FOR ORTHODONTIC DIAGNOSIS AND TREATMENT PLANNING
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Hubbold, R.J.
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Eid, A.A.
NUMERICAL SIMULATION AND VIDEO DISPLAY OF DYNAMIC PROBLEMS
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Janick, CARNET
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Jacques, DUJARDIN
DIRECT CADD DRAWING (A Flexible Screen Oriented user interface to CADD)
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Hudson, Fred W.
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Jr.,
THE DEVELOPMENT OF COMPUTER GRAPHICS CURRICULA FOR DESIGN EDUCATION
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King, Robin G.
THE COMPUTER GRAPHICS SCENE IN THE UNITED STATES
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Badler, Norman I.
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Carlbom, Ingrid
GENERATING HIGH QUALITY PICTURES BY RAY-TRACING
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BOUVILLE, C.
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DUBOIS, J.L.
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MARCHAL, I.
USER INTERFACE: CONCEPTS AND SPECIFICATIONS
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Spliid, Axel Monrad
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Sorgen, Amos
IMPROVING COMPUTER GRAPHICS TOOLS FOR ARCHITECTS
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Ekeberg, Oerjan
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Engblom, Carl-Henrik
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Kjelldahl, Lars
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Lundequist, Jerker
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Thörnblom, Ingvar
EXPERIENCES WITH NEW IMAGE COMPONENT ALGORITHMS
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Samet, Hanan
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Tamminen, Markku
COMPUTER GRAPHICS FOR VISUALIZING SIMULATION RESULTS
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NAKAMAE, Eihachiro
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YAMASHITA, Hideo
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NISHITA, Tomoyuki
GRAPHICAL SUPPORT IN A USER INTERFACE MANAGEMENT SYSTEM
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Guest, Steve
;
Edmonds, Ernest
BILEVEL DISPLAY SCREEN PRESENTATION OF TEXT, GRAPHICS AND IMAGES FOR PAGE MAKE-UP WORK
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Sundblad, Yngve
AN APPROACH TO THE DESIGN OF HARDWARE CURVE GENERATORS FOR GRAPHIC DISPLAYS
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Alia, G.
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Martinelli, E.
;
Tani, N.
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Item 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. TUCKERTo 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.Item A NEW DISPLAY FILE STRUCTURE FOR LINE AND SURFACE PRESENTATIONS(The Eurographics Association, 1984) Krmer, Thomas; Rix, Joachim; K. BO and H.A. TUCKERIn 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.Item APPLICATION OF COMPUTER-GENERATED ANIMATION IN EUROPEAN SPACE RESEARCH(The Eurographics Association, 84) Kristiansen, E.; K. BO and H.A. TUCKERIn 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.Item A PAINT PROGRAM FOR THE GRAPHIC ARTS IN PRINTING(The Eurographics Association, 84) Willis, P J; K. BO and H.A. TUCKERThere 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.Item AN ANALYTICAL VISIBILITY METHOD FOR DISPLAYING PARAMETRICALLY DEFINED SURFACES(The Eurographics Association, 1984) Rehwald, Peter; Hornung, Christoph; K. BO and H.A. TUCKERThis 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.Item RAY TRACING OBJECTS DEFINED BY SWEEPING A SPHERE(The Eurographics Association, 1984) Wijk, J.J. van; K. BO and H.A. TUCKERThe 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.Item Twixt: A 3D Animation System(The Eurographics Association, 1984) Gomez, Julian E.; K. BO and H.A. TUCKERThis 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.Item 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. TUCKERThis 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.Item CADASTRAL MAPPING PILOT PROJECT(The Eurographics Association, 1984) Sondergaard, Aage; K. BO and H.A. TUCKERThe 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.Item 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. TUCKERInteractive 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.Item CONVENTIONAL ELEMENTS OF ENGINEERING DRAWINGS - FREE FORM CURVES(The Eurographics Association, 1984) Renner, G.; K. BO and H.A. TUCKERTechnical 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.Item NUMERICAL SIMULATION AND VIDEO DISPLAY OF DYNAMIC PROBLEMS(The Eurographics Association, 1984) Janick, CARNET; Jacques, DUJARDIN; K. BO and H.A. TUCKERThe 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.Item DIRECT CADD DRAWING (A Flexible Screen Oriented user interface to CADD)(The Eurographics Association, 1984) Hudson, Fred W.; Jr.,; K. BO and H.A. TUCKERComputer 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.Item THE DEVELOPMENT OF COMPUTER GRAPHICS CURRICULA FOR DESIGN EDUCATION(The Eurographics Association, 1984) King, Robin G.; K. BO and H.A. TUCKERWith 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.Item THE DESIGN OF A USER INTERFACE FOR A CAM APPLICATION(The Eurographics Association, 1984) Sauter, Roland; K. BO and H.A. TUCKERThis 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.Item INTERACTIVE EDITING OF POLYGONS(The Eurographics Association, 1984) Olsson, Lennart; K. BO and H.A. TUCKERThis 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.Item QUADTREE SCAN CONVERSION(The Eurographics Association, 1984) Oliver, M.A.; King, T.R.; Wiseman, N.E.; K. BO and H.A. TUCKERAn 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.Item SHAPING THE FUTURE A SYSTEMS APPROACH TO MIS PLANNING(The Eurographics Association, 1984) Kirkley, John L.; K. BO and H.A. TUCKERItem SUDS - SUrface Description System(The Eurographics Association, 1984) Moretonl, Henry P.; Bergeron, R. Daniel; K. BO and H.A. TUCKERA 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.Item THE COMPUTER GRAPHICS SCENE IN THE UNITED STATES(The Eurographics Association, 1984) Badler, Norman I.; Carlbom, Ingrid; K. BO and H.A. TUCKERWe 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.Item GENERATING HIGH QUALITY PICTURES BY RAY-TRACING(The Eurographics Association, 1984) BOUVILLE, C.; DUBOIS, J.L.; MARCHAL, I.; K. BO and H.A. TUCKERRay-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.Item USER INTERFACE: CONCEPTS AND SPECIFICATIONS(The Eurographics Association, 1984) Spliid, Axel Monrad; Sorgen, Amos; K. BO and H.A. TUCKERA 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.Item COMPUTER GRAPHICS DEVELOPMENT IN EUROPE(The Eurographics Association, 1984) Marechal, Guy; Matthys, Jan; K. BO and H.A. TUCKEREurope 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.Item 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. TUCKERDuring 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.Item TWO DISPLAY ALGORITHMS FOR OCTTREES(The Eurographics Association, 1984) Oliver, M.A.; K. BO and H.A. TUCKERThis 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.Item EXPERIENCES WITH NEW IMAGE COMPONENT ALGORITHMS(The Eurographics Association, 1984) Samet, Hanan; Tamminen, Markku; K. BO and H.A. TUCKERWe 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.Item STEPS TO EFFECTIVE BUSINESS GRAPHICS(The Eurographics Association, 1984) Macllroy, AI; Wyman, Peggy; K. BO and H.A. TUCKERItem COMPUTER GRAPHICS FOR VISUALIZING SIMULATION RESULTS(The Eurographics Association, 1984) NAKAMAE, Eihachiro; YAMASHITA, Hideo; NISHITA, Tomoyuki; K. BO and H.A. TUCKERComputer 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.Item DRAWING OF AN UNUSUAL KIND OF DIAGRAMS - NOMOGRAM DRAWING(The Eurographics Association, 1984) Kjelldahl, Lars; K. BO and H.A. TUCKERDiagram 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.Item COMPUTER GRAPHICS PRODUCTION AS A BUSINESS(The Eurographics Association, 1984) Kaneko, Mitsuru; K. BO and H.A. TUCKERItem A TWO-DIMENSIONAL CLIPPING DIVIDER(The Eurographics Association, 1984) MERIAUX, Michel; K. BO and H.A. TUCKERThe 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.Item GRAPHICAL SUPPORT IN A USER INTERFACE MANAGEMENT SYSTEM(The Eurographics Association, 1984) Guest, Steve; Edmonds, Ernest; K. BO and H.A. TUCKERSYNICS2 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.Item 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. TUCKERLimitations 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.Item HOW INTELLIGENT CAN BUSINESS GRAPHICS SOFTWARE BE?(The Eurographics Association, 1984) Jones, Peter R.; K. BO and H.A. TUCKERThis 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).Item 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. TUCKERSpecial 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.