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Has files: true × End date: 1989 × Start date: 1980 ×

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Now showing 1 - 10 of 345
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    GRAPHIC DISPLAYS IN THE COMPUTER AIDED DESIGN OF LIFT SYSTEMS
    (The Eurographics Association, 1982) Barney, G.C.; D.S. Greenaway and E.A. Warman
    The sizing of lift systems to meet passenger demands is normally carried out in a quantitative way by calculation. Nothing is done to determine the quality of service provided. This paper describes how a computer aided design suite using discrete simulation techniques coupled to extensive graphic displays overcomes these deficiencies.
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    Free-Form Surfaces Modeling by Evolution Simulation
    (Eurographics Association, 1988) Lienhardt, Pascal
    We present in this paper a procedural method for modeling free-form, planar surfaces subdivisions, which allows simulating evolutions of such subdivisions. This method is founded on the common principles deduced from corpuscular phenomena modeling method (particle systems), and method for vegetal trees modeling by simulation of evolution. These principles are : - use of a discrete model, which is a set of basic elements, from which time discretization is deduced, -proper activity of basic elements; these methods consists in simulating the behaviour of these elements; - characterization of modelled object evolution, which is achieved by "functions" associated to basic elements; - priority of topology over geometry. A surface is defined as a set of surface elements, supported by a rooted, planar tree. A surface is initially reduced to a point. Surface evolution characterization and control are exclusively exerted through this tree. This method is applied to image synthesis and animation of natural shapes, especially vegetal shapes.
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    HUTWINDOWS: AN APPROACH TO USER INTERFACE DEVELOPMENT
    (The Eurographics Association, 1985) Koivunen, Marja-Riitta; Mntyl, Martti; C.E. Vandoni
    The design and implementation of good graphical user interfaces is a difficult task requiring good taste and proper tools. The HutWindows system under development at Helsinki University of Technology is intended to be an easy-to-use set of tools for implementing a graphical user interface to an application having a simple text-oriented interface. It provides a single input channel for interleaved input from a collection of non-overlapping windows, and output primitives for the display of text and graphics. All details of the user interface are effectively hidden from the application, and can be modified by the user without touching the application code.
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    A Three-Dimensional Shaded Display Method for Voxel-Based Representation
    (The Eurographics Association, 1985) OHASHI, Toshiaki; UCHIKI, Tetsuya; TOKORO, Mario; C.E. Vandoni
    In this paper, methods for displaying solid objects represented by a three-dimensional array of voxels are described. The Linear Interpolating Projection Method is proposed as a method by which such objects can be projected onto the screen in perspective. In order to shade the projected images, the Depth only Shading Method is proposed. These methods are so simple that three-dimensional perspective images with shading can be produced rapidly. This paper also describes an architecture based on these methods for generating animation interactively.
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    Blending Rational B-Spline Surfaces
    (Eurographics Association, 1989) Bardis, L.; Patrikalakis, N.M.
    A method for blendin non uniform rational B-spline surface patches, either open or periodic, is developed. he blending surface is expressed in terms of an integral, bicubic B-spline patch. The blend ensures position and normal vector continuity along linkage curves to within a specified accuracy. The linkage curves are either user-defined or are obtained by offsetting the intersection of the two patches using geodesics on each patch. An example illustrates the applicability of our method.
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    DETERMINATION OF LOCAL COORDINATE SYSTEMS FOR TEXTURE SYNTHESIS ON 3-D SURFACES
    (The Eurographics Association, 1985) MA, SONG DE; GAGALOWICZ, ANDRE; C.E. Vandoni
    We propose and compare three types of local coordinate systems and describe their geometric properties Several results of texture synthesis on 3-D surfaces using these local coordinate systems are presented The synthesis procedure is driven by a texture model including only a small amount of statistical parameters
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    TOWN PLANNING AIDED BY AN INTEGRATED MUNICIPAL LAND INFORMATION SYSTEM
    (The Eurographics Association, 1981) Eloranta, Kirsi; J. L. Encarnacao
    The purpose of this paper is to describe the results of our recent land information systems research in The Institute of Geodesy at Helsinki University of Technology. Our goal is to make research on municipal systems by building pilot systems and also by studying technical implementation problems on theoretic basis. In this paper one of our pilot systems is described, the one that is designed for town planning applications. Generally the research project could be characterized by the following keywords: use of minicomputers, problem oriented approach, evolutive approach in systems design, applications oriented data base management and integration of urban land information systems.
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    Fast Previewing Techniques in Raster Graphics
    (The Eurographics Association, 1983) Jansen, F.W.; Wijk, J.J. van; P.J.W. ten Hagen
    The long processing times inherent in the use of raster graphics techniques for the shading of complex scenes, complicate the design and debugging of a picture. The efficiency of the picture-generating process can, however, be improved by adding several interactive facilities to the system. In particular, fast previewing techniques are valuable for checking the modeling and for getting a good impression in an early stage of the picture-definition process. A discussion of raster graphics system design is followed by examples of fast pre-viewing techniques for the shading and texture mapping of surface models and for the shading of solid models using a raycasting technique.
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    Architectures for Mass Market 3D Displays
    (Eurographics Association, 1988) Winser, Paul; Bonnet, Thierry; Dumont, Dominique; Mathieu, Yves
    We discuss the specific architecture requirements of real time 3D display systems intended for low cost mass market products of the near future. Vertex transformation and polygon rendering are two processing aspects where hardware acceleration must be used to achieve the performance target. The use of one or more DSP chips as vertex processors is discussed, and two efficient z-buffer implementations described. Antialiasing and texture mapping greatly improve the visual impression at some processing cost.
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    Variations on a Dither Algorithm
    (Eurographics Association, 1989) Pins, Markus; Hild, Hermann
    Mapping continuous-tone pictures into digital halftone pictures, i.e. 0/1-pictures, for printing purposes is a well explored technique. In this paper, one of these algorithms, the two-dimensional error-diffusion algorithm is extended to color pictures and animated pictures. The color picture algorithm is superior to existing algorithms by considering extreme color values as well as adjacent color values. The animation algorithm eliminates the noise created by the correct but varying pixel patterns generated by applying a single picture dithering algorithm on every frame. The power of the algorithms is demonstrated by experiments carried out on synthetic images generated by ray tracing.