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Now showing 1 - 10 of 1288
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    Simulation of Facial Muscle Actions Based on Rational Free Form Deformations
    (Blackwell Science Ltd and the Eurographics Association, 1992) Kalra, Prem; Mangili, Angelo; Thalmann, Nadia Magnenat; Thalmann, Daniel
    This paper describes interactive facilities for simulating abstract muscle actions using Rational Free Form Deformations (RFFD). The particular muscle action is simulated as the displacement of the control points of the control-unit for an RFFD defined on a region of interest. One or several simulated muscle actions constitute a Minimum Perceptible Action (MPA), which is defined as the atomic action unit, similar to Action Unit (AU) of the Facial Action Coding System (FACS), to build an expression.
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    Haptic Simulation, Perception and Manipulation of Deformable Objects
    (The Eurographics Association, 2007) Magnenat-Thalmann, Nadia; Volino, Pascal; Bonanni, Ugo; Summers, Ian R.; Brady, A. C.; Qu, J.; Allerkamp, D.; Fontana, M.; Tarri, F.; Salsedo, F.; Bergamasco, Massimo; Karol Myszkowski and Vlastimil Havran
    This tutorial addresses haptic simulation, perception and manipulation of complex deformable objects in virtual environments (VE). We first introduce HAPTEX, a research project dealing with haptic simulation and perception of textiles in VEs. Then, we present state-of-the-art techniques concerning haptic simulation and rendering, ranging from physically based modelling to control issues of tactile arrays and force-feedback devices. In the section on cloth simulation for haptic systems we describe techniques for simulating textiles adapted to the specific context of haptic applications. The section concerning tactile aspects of virtual objects shows how arrays of contactors on the skin can be used to provide appropriate spatiotemporal patterns of mechanical excitation to the underlying mechanoreceptors. Finally, the last section addresses the problem of developing suitable force feedback technologies for the realistic haptic rendering of the physical interaction with deformable objects, addressing the design of novel force feedback systems, innovative concepts for curvature simulation and control algorithms for accuracy improvement.
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    An Accurate Illumination Model for Objects Coated with Multilayer Films
    (Eurographics Association, 2000) Hirayama, H.; Kaneda, K.; Yamashita, H.; Monden, Y.
    This paper proposes an accurate illumination model for rendering objects coated with multilayer films. Optical phenomenaof multilayer films are caused by reflection, refraction, interference, and absorption of light inside each layer of multiple films, and these physical phenomena are complicatedly related with each other. The proposed method calculates composite reflectance and transmittance of multilayer films, taking into account all the physical phenomena described above, and visualizes the optical phenomena caused by the multilayer films accurately. The illumination model proposed in the paper can handle both smooth surface and locally smooth rough surfaces. Several examples of objects coated with various kinds of films demonstrate the usefulness of the proposed method.
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    A Graph-Based Approach to Surface Reconstruction
    (Blackwell Science Ltd and the Eurographics Association, 1995) Mencl, Robert
    A new approach to the reconstruction of a surface from an unorganized set of points in space is presented. The point set may for example be obtained with a laser scanner or a manual digitizing tool, and is the only source of information about the shape of the acquired object. The basic idea is to calculate the Euclidean minimum spanning tree (EMST) of the given points. The EMST is then augmented to the so-called surface description graph (SDG). Finally the wire frame defined by the SDG are filled with triangles. The advantage of our approach is that also highly non-convex and even disconnected surfaces are reconstructed quite reliably. This is demonstrated for a variety of data sets.
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    Template-Based Volume Viewing
    (Blackwell Science Ltd and the Eurographics Association, 1992) Yagel, Roni; Kaufman, Arie
    We present an efficient three-phase algorithm for volume viewing that is based on exploiting coherency between rays in parallel projection. The algorithm starts by building a ray-template and determining a special plane for projection - the base-plane. Parallel rays are cast into the volume from within the projected region of the volume on the base-plane, by repeating the sequence of steps specified in the ray-template. We carefully choose the type of line to be employed and the way the template is being placed on the base-plane in order to assure uniform sampling of the volume by the discrete rays. We conclude by describing an optimized software implementation of our algorithm and reporting its performance.
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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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    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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    Combining finite element deformation with cutting for surgery simulations
    (Eurographics Association, 2000) Nienhuys, Han-Wen; van der Stappen, A. Frank
    Interactive surgery simulations have conflicting requirements of speed and accuracy. In this paper we show how to combine a relatively accurate deformation model—the Finite Element (FE) method—and interactive cutting without requiring expensive matrix updates or precomputation. Our approach uses an iterative algorithm for an interactive linear FE deformation simulation. The iterative process requires no global precomputation, so runtime changes of the mesh, i.e. cuts, can be simulated efficiently. Cuts are performed along faces of the mesh; this prevents growth of the mesh. We present a provably correct method for changing the mesh topology, and a satisfactory heuristic for determining along which faces to perform cuts. The incision surface will be jagged; this problem is a subject of current research.
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    High Dynamic Range Techniques in Graphics: from Acquisition to Display
    (The Eurographics Association, 2005) Goesele, Michael; Heidrich, Wolfgang; Höfflinger, Bernd; Krawczyk, Grzegorz; Myszkowski, Karol; Trentacoste, Matthew; Ming Lin and Celine Loscos
    This course is motivated by tremendous progress in the development and accessibility of high dynamic range technology (HDR) that happened just recently, which creates many interesting opportunities and challenges in graphics. The course presents a complete pipeline for HDR image and video processing from acquisition, through compression and quality evaluation, to display. Also, successful examples of the use of HDR technology in research setups and industrial applications are provided. Whenever needed relevant background information on human perception is given which enables better understanding of the design choices behind the discussed algorithms and HDR equipment.
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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.