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Item HUTWINDOWS: AN APPROACH TO USER INTERFACE DEVELOPMENT(The Eurographics Association, 1985) Koivunen, Marja-Riitta; Mntyl, Martti; C.E. VandoniThe 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.Item A Three-Dimensional Shaded Display Method for Voxel-Based Representation(The Eurographics Association, 1985) OHASHI, Toshiaki; UCHIKI, Tetsuya; TOKORO, Mario; C.E. VandoniIn 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.Item DETERMINATION OF LOCAL COORDINATE SYSTEMS FOR TEXTURE SYNTHESIS ON 3-D SURFACES(The Eurographics Association, 1985) MA, SONG DE; GAGALOWICZ, ANDRE; C.E. VandoniWe 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 parametersItem FRACTIONAL BROWNIAN RELIEF : AN EXACT LOCAL METHOD(The Eurographics Association, 1985) FELLOUS, A.; GRANARA, J.; HOURCADE, J. C.; Vandoni, C. E.Fractional Brownian process has been widely used for computer rendering of terrain models. The implementation constraints in Computer Graphics have led to the use of recursive methods, based on some local properties of this model. We present in this article s mathematical study of these local properties and propose a local model for fractal modeling based on strict observance of fractional Brownian probability law.Item MODEL DRIVEN SYNTHESIS OF NATURAL TEXTURES FOR 3-D SCENES(The Eurographics Association, 1985) GAGALOWICZ, ANDRE; MA, SONG DE; C.E. VandoniThis paper presents a new method for the synthesis of textures on 3-D surfaces. With the exception of fractals, graftals and particle systems used for very restricted types of textures, one basic technique for the faithful reproduction of textures has been presented in the literature up to now. In this standard method, textures are synthesized by mapping a rectangular template onto a patch of the curved surface. In the method proposed here, the synthesis is achieved continuously on the surface by interpolating only statistics of the texture which have a much narrower spectrum than the texture itself so that there are no aliasing effects. A vast class of textures can be reproduced with a visual appearance similar to the reference texture used. The method applies for any 3-D surface and is relatively quick and easy.Item Moving Picture Synthesis at Linkoping University(Blackwell Publishing Ltd and the Eurographics Association, 1985) Fahlander, OlovWe believe that in the future we will see a diverse variety of applications in the now emerging technology of real time computer animation. Such animations impose stringent computational and bandwidth demands on the underlying system. It is important to investigate carefully the methods best suited to the particular requirements of animation when motion is involved.1,2,3 In this paper we describe a system - Retina - which is now operational. We discuss the underlying concept of parameterization, which is of fundamental importance to the software design. Some timing data for this system will be given. A short description of the 3D editor, which is currently under development, is also given.Item VIEWING SOLID MODELS BY BINTREE CONVERSION(The Eurographics Association, 1985) Koistinen, Petri; Tamminen, Markku; Samet, Hanan; C.E. VandoniA hidden surface algorithm is presented for viewing constructive solid geometry representations of solids (CSG trees) by converting them implicitly into a 3-d recursive spatial subdivision (bintree). The algorithm prunes the CSG tree to its minimal representation within each bintree block and does not evaluate it in regions of space (bintree nodes) that are totally hidden to the observer.Item Report of the Timberline Meeting of ISO TC97/SC21/WG2 "Computer Graphics"(Blackwell Publishing Ltd and the Eurographics Association, 1985) Bono, Peter R.Item GRAPHICS PROGRAMMING FOR KNOWLEDGE-GUIDED INTERACTION(The Eurographics Association, 1985) Tibbert, Lee; Bergeron, R. Daniel; C.E. VandoniThis paper describes a design approach that combines knowledge engineering techniques with an interactive graphics program. A prototype for specifying computer systems interactively is used to demonstrate the design approach. The program incorporates a rule-based knowledge engineering module which allows for both data base consistency and the ability to guide the user through an interactive dialogue.Item Concerning the Specification of User Interfaces(Blackwell Publishing Ltd and the Eurographics Association, 1985) Duce, D. A.