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Now showing 1 - 10 of 78
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    Dynamic Load Balancing within a High PerformanceGraphics System
    (The Eurographics Association, 1991) Selzer, Harald; A. Kaufman
    Interactive 3D graphics applications require significant arithmetic processing to meet the ever-inreasing desire for higher image complexity and higher resolution in displayed images. This paper describes a graphics processor architecture with a high degree of parallelismconnected to a distributed frame buffer. The architecture can be configured with an arbitrary number of identical, high level programmable processors operating in parallel.Within the architecture an automatic load balancing mechanism is presented whichdistributes the processing load between geometry and rendering section. After the unique features of the architecture are described the load balancing mechanismis analyzed and the increase of performance is demonstrated."
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    Constructive Page Description Opening Up the Prepress World
    (Eurographics Association, 1991) Samara, Veronika; Wiedling, Hans-Peter
    Constructive Page Description (CPD) is an overall approach allowing different kinds of data to be exchanged between a variety of systems and manipulated in arbitrary system environments. Fully changeable pages, which keep information for modification as long as necessary, as well as fully assembled pages, ready for the printing process, can be constructed by the use of CPD. Moreover, descriptions of data as well as operations can be distributed, and so allow the use of networking facilities. CPD is thereby very flexible in handling, combining, and exchanging data and operations used in the construction of pages. In sum, CPD helps bridge the gap between the printing and the computer graphics world; it is an approach to lead prepress towards an open system architecture.
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    Development of an Intelligent Wheelchair Using Computer Graphics Animation and Simulation
    (Blackwell Science Ltd and the Eurographics Association, 1991) Ojala, Jari; Inoue, Kenji; Sasaki, Ken; Takano, Masaharu
    A new robot simulator JC-1 is used as a control software development tool in a project in progress where an intelligent wheelchair for a blind user is being developed. The intelligent wheelchair is planned to be able to fulfill simple symbolic commands like"follow wall" or"follow object" and using the JC-1 simulator an evaluation team which includes e.g. the user, a rehabilitation engineer and a software engineer, can check control algorithms and user interface routines before constructing a real wheelchair prototype. The JC-1 simulator models the environment using simplified boundary- representation where objects, robot sensors and actuators are presented as symbolic objects in the graphics data-base of the simulator. In the JC-1 simulator a robot controller under development controls the motion of the graphical model of the robot while simulator commands or other robot controllers can be used to control the movement of disturbing obstacles. Computer graphics animation and simulation help to find fundamental design errors at an early design stage and as this paper suggests, enable the user of the final product to take part in to the designing process of the robot controller. Benefits and difficulties of using computer graphics simulation in the wheelchair development process are discussed.
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    Refinement criteria for adaptive stochastic ray tracing of textures
    (Eurographics Association, 1991) van Walsum, Theo; van Nieuwenhuizen, Peter R.; Jansen, Frederik W.
    Adaptive stochastic ray tracing is a rendering technique that generates high-quality anti-aliased images by sampling the image in a non-regular pattern that is adaptively refined. Image refinement can be guided by image space or object space criteria. For display of textures, additional criteria that operate in texture space can be added to further improve image quality. In this paper three texture space refinement criteria are introduced. The methods minimize the chance of sampling errors at the cost of only a small amount of preprocessing and are comparable in efficiency with existing texture prefiltering methods.
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    Several approaches to implement the merging step of the split and merge region segmentation
    (Eurographics Association, 1991) Popovic, M.; Chantemargue, F.; Canals, R.; Bonton, P.
    The purpose of this paper is to propose several approaches for the implementation of the merging step of split and merge region segmentation. The splitting step has already been studied and its parallelization has subsequently been implemented on a transputer network. First, the most widely known merging step is described. Then, two approaches which are better suited to a parallelization are presented. Next we discuss the principle behind these approaches. Finally region segmentation according to motionbased criteria has been chosen in order to provide results to evaluate the performance of each approach. We emphasize that the description is general and can be applied to all split and merge algorithms. Therefore this work is a contributory factor in the evolution of region segmentation towards its parallelization.
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    Variable-Radius Blending by Using Gregory Patches in Geo- metric Modeling
    (Eurographics Association, 1991) Harada, T.; Konnoa, K.; Chiyokura, H.
    Blending surfaces, which connect two curved surfaces smoothly, often appear in geometric modeling. Many of the blending surfaces are variable-radius blends. Variableradius blending surfaces are very important in the design process, but it is difficult to generate such surfaces with existing geometric modelers. This paper proposes a new method to generate variable-radius blends. Instead of the popular rolling-ball method, we adopt “sliding-circle” blending. A circle slides on two curved surfaces so that the circle is perpendicular to a specified control curve, and its trajectory defines a blending surface. A variable-radius blend can be generated if the radius of the circle changes smoothly. In our method, the shape of the variable-radius blend is represented by Gregory patches. The Gregory patch is an extension of a Bezier patch and two Gregory patches can be connected together with tangential continuity. The characteristics of the Gregory patch are suitable for representing blending surfaces with geometric modelers.
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    Integrating Inheritance and Composition in an Objective Presentation Model for Multiple Media
    (Eurographics Association, 1991) Took, Roger
    A formal model is presented which combines, in a single structure called a tangle, the power to express both the composition of aggregate objects, and the selective inheritance of object properties over a number of instances or manifestations. The model allows an objective implementation, that is, one in which objects can be created and updated randomly, incrementally, and dynamically. Such a model is ideal as the basis for interactive presentation. The tangle is defined as generic in its node type, and so can model the structure of multiple presentation media.
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    Using temporal and spatial coherence for accelerating the calculation of animation sequences
    (Eurographics Association, 1991) Gröller, Eduard; Purgathofer, Werner
    Ray tracing is a well known technique for generating realistic images. One of the major drawbacks of this approach are the extensive computational requirements for image calculation. When generating animation sequences frame by frame the computational cost might easily become intolerable. In the last years several methods have been devised for accelerating the computational speed by using spatial and temporal coherence. While these techniques work only under certain restrictions, a new approach is presented in this paper which leads to a considerable speed-up of the calculation process without putting any limitations on camera or object movement. In principle, the method is an extension of /ArKi87/, where rays are considered points in 5D space, by the time dimension. CSG is used for object description and has been modified correspondingly to allow easy use of coherence properties. The paper describes the theoretical background and the main concepts of a practical implementation.
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    The Formal Specification of Level la of GKS
    (Blackwell Science Ltd and the Eurographics Association, 1991) Damnjanovic, Ljiljana B.
    In this paper the formal specification of a part of level la of GKS is given in the algebraic specification language OBJ. It shows that it is possible to produce a formal specification of a substantial part of GKS which is of manageable size and complexity specifying the appropriate level of abstraction of the system and using a suitable formal technique.