Volume 07 (1988)

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A Survey of Computer Animation
(Blackwell Publishing Ltd and the Eurographics Association, 1988) Pueyo, Xavier; Tost, Daniela
A survey on computer animation is presented with three specific goals: * .To clarify what people understand by computer animation. * .To separate the different aspects of computer animation and underline its main problems. * .To present the different solutions given to these problems.Several classifications for computer animation systems are first made attending to different criteria. The report is subsequently divided into two basic sections according to the historical classification of computer animation systems: computer-assisted animation, where traditional animation is just helped by the use of computers, and modelled animation where the use of computers is essential in different aspects of the animation process. Special emphasis is placed on motion specification and generation.Finally, special attention is paid to human body animation because of the great interest of this specific field of computer animation and the peculiarity of its problems.Aspects of hardware aspects and postprocessing has just been taken into account in the classification section but have not been studied.
EDITORIAL
(Blackwell Publishing Ltd and the Eurographics Association, 1988)
Experimenting with a Parallel Ray-Tracing Algorithm on a Hypercube Machine
(Eurographics Association, 1988) Priol, Thierry; Bouatouch, Kadi
A parallel space tracing algorithm is presented. It subdivides the scene into regions. These latter are distributed among the processors of an iPSC hypercube machine designed by Intel company. Each processor subdivides its own region into cells to accelerate the ray tracing algorithm. Processors communicate by means of messages. The pyramidal shape of the regions allows the deletion of the primary ray messages. A method of performing a roughly uniform load distribution is proposed.
A Method for Providing Full Interactive Control of the Shape of 3-D Curves and Surfaces
(Eurographics Association, 1988) Cros, Frederic; Brock, Philip J.
This paper presents a new method for providing an interactive local control on 3-D curves and surfaces. The possibility of interacting directly on the vector tangent to the curve at each control point (e.g. changing its magnitude and direction) gives the user a more intuitive control for shaping a curve than if he has to manipulate "abstract" parameters (like bias or tension). This technique is based on the use of Cardinal-splines and can also provide a means to obtain local control on surfaces.
Computer Graphics and Computer-Aided Design Literature: A Keyword-Indexed Bibliography for the Year 1987
(Blackwell Publishing Ltd and the Eurographics Association, 1988) Owen, Jon
Report on the Third Eurographics Workshop on Graphics Hardware
(Blackwell Publishing Ltd and the Eurographics Association, 1988) Blake, E.H.
Experience with Chisl, a Configurable Hierarchical Interface Specification Language
(Blackwell Publishing Ltd and the Eurographics Association, 1988) Wood, C.A.; Gray, P.D.; Kilgour, A.C.
This paper describes the design, implementation and initial evaluation of a graphical dialogue specification language and its interpreter. Features of the system include a hierarchical dialogue structure with the capability to export options to lower levels of the hierarchy, the use of a restricted form of production rule approach to option selection in each unit of the dialogue, and suspended time editing (allowing modification of the dialogue specification during execution without loss of context).
Report on the International Conference"Theory and Practice of Geometric Modelling"
(Blackwell Publishing Ltd and the Eurographics Association, 1988) Seidel, Hans-Peter
A Procedural System for the Definition and Storage of Technical Drawings in Parametric Form
(Eurographics Association, 1988) Cugini, U.; Folini, F.; Vicini, I.
The construction of a truly USER-FRIENDLY CAD system requires the acquisition and management of a tremendous amount of information which cannot be. and must not be. directly requested from the user, but which has to be obtained by intelligently interpreting the sequence of operations performed by him. The system described here is out forward as a USERFRIENDLY tool for the definition. storage and modification of technical drawings in parametric form. The system that has been implemented (GIPS Graphic Interactive Parametric System) assists the user during the steps of definition and modification. taking advantage of the abiIity to interpret the procedure the user follows in describing the object he wants to design.
A System for Graphical Interaction on Parametrized Models
(Eurographics Association, 1988) Van Emmerik , Maarten J.G.M.
A system that enables the definition of parametrized solid models by means of graphical interaction is presented. The position, orientation and dimensions of primitive volumes for Constructive Solid Geometry (CSG) are determined by a number of control points. All control points are linked to nodes in a tree of local coordinate systems. The relations between control points is therefore determined by the relations of the nodes in this geometric tree. The user can create nodes and define geometric relations between them by graphical interaction on the geometric tree. With the system described in this paper, it is possible to define relations
Report on the"CGM in the Real World" Workshop (NBS, Wasington)
(Blackwell Publishing Ltd and the Eurographics Association, 1988) Carr, R.; Pink, J.
IXPHIGS: A Portable Implementation of the International PHIGS Standard
(Eurographics Association, 1988) Gorog, Jenö; Krammer, Gergely; Vincze, Arpad
This paper describes a "portable" object-oriented implementation of the international standard PHIGS. A rapid prototype has been achieved by making use of earlier developments : the IX-CGI module for graphical input, output and interaction and IX-TAM for the creation of and access to objects of different classes, and thus the creation, manipulation and traversal of graph structures with different classes of leaf objects, The “post” function of PHIGS by definition is applied to structure node objects. For each node, it goes. through the element list of the node and, for each element in the list, it invoker the post function of the appropriate element class. Standard extensions are incorporated into this IX-POST module. The limited capabilities provided by the PHIGS input functions are enhanced by an additional interaction interface module IX-IF. A STRUCture e d i TOR program built on top of the PHIGS application interface serves not only as a demonstration of PHIGS capabilities but also as a turnkey program for the wide class of applicaticans with the task of creating and editing symbolic drawings. IXPHIGS is written in the language C and it is a "full software implementation" of all PHIGS capabilities, even for parts which may he enhanced later by using advanced hardware on some target configurations.
Architectures of Graphic Processors for Interactive 2D Graphics
(Blackwell Publishing Ltd and the Eurographics Association, 1988) Fontenier, Guy; Gros, Pascal
Interactive 2-D systems have benefited greatly from the improvements in 1C technology. Today, the trend is to relieve the host computer from low level tasks through increasing the graphic system s computational power. The introduction of video RAMs has solved the problem of contention for memory cycles between the display generator and the video refresh controller. The improvements in graphic controllers have led from the first fixed instructions controllers to today s third generation of programmable graphic processors, able to support computer graphic interface standards. This article will present this evolution, and focus on a 2-D graphic processor designed at the Imagery, Instrumentation and Systems Laboratory, based on the separation of graphic generation and memory management functions.
Third Eurographics Workshop on Graphics Hardware
(Blackwell Publishing Ltd and the Eurographics Association, 1988)
Optimal Texture Mapping
(Eurographics Association, 1988) De Ma, Song; Lin, Hong
Texture mapping is one of the most important techniques for highquality image synthesis. It can enhance immensely the visual richness of raster-scan images. We address in this paper the problem of mapping planar texture pattern onto arbitrarily curved surfaces. It is well known that such a mapping will inevitably produce distortion for any undevelopable surface. Although many techniques for texture mapping have been presented in the literature [1], to our knowledge, no general method existed which could control or minimize this distortion. We present in this paper a new method for texture mapping. The main idea is to develop the given curved surface approximately on a two-dimensional plane using an approximate locally isometric mapping while minimizing the distortion by an optimization technique. Our experience has shown that by using this technique, one can reduce considerably the distortion and thus improve the quality of the generated images.
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.
Third Alvey Vision Conference University of Cambridge 15-17 September 1987
(Blackwell Publishing Ltd and the Eurographics Association, 1988) CrennelF, K. M.
A Proposal for a Distributed Model of GKS Based on Prolog
(Blackwell Publishing Ltd and the Eurographics Association, 1988) Milanese, V.
The Graphical Kernel System GKS is so well established as a standard for graphics programming that quite a number of models for multiprocessor and distributed environments have already been suggested. It is therefore necessary to consider new languages and methodologies capable of supporting its distributed implementation. In this context, clausal logic languages provide suitable means for describing the system in a declarative form and, moreover, ensure the applicability of meta-programming techniques for specifying the semantics of implementation. The Prolog language, extended with communication and modularization structures required by the distributed programming, is thus here considered as a feasible means for establishing a model of GKS organized in functional modules which could be supported by different processors. For such a model a two-level implementation scheme is outlined and a reconfiguration and personalization methodology is suggested.
A Note on Random Thresholding for Colour Synthesis
(Blackwell Publishing Ltd and the Eurographics Association, 1988) Lastra, G.L.; Rudinger, E.N.
A simple algorithm that improves colour shaded images is presented. The algorithm does not trade spatial resolution for intensity resolution. The basic technique, based on random thresholding modulated by a pseudo-random number generator of uniform distribution, is introduced to render halftone images on bi-level displays. A generalization of the technique is done for displays with multiple bi-per-colour components. An obvious advantage of the algorithm presented over other reported methods is its simplicity. Pictures are included to show results of the algorithm.
G1 Smoothing Solid Objects by Bicubic Bezier Patches
(Eurographics Association, 1988) Liang, Youdong; Ye, Xiuzi; Fang, Shiaofen
A general and unified method is presented for generating a wide range of 3D objects by smoothing the vertices and edges of a given polyhedron with arbitrary topology using bicubic Bezier patches. The common solution to the compatibility equations of geometric continuity between two Bezier patches is obtained and employed as the foundation of this new method such that this new solid and surface model is reliable and compatible with the solid modeling and surface modeling system in the most common use. The new method has been embeded in an algorithm supported by our newly developed solid modeling system MESSAGE. The performance and implementation of this new algorithm show that it is efficient, flexible and easy to manipulate.

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