23-Issue 1

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https://diglib.eg.org/handle/10.2312/114

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    7th International Workshop on Immersive Projection Technology and 9th Eurographics Workshop on Virtual Environments
    (The Eurographics Association and Blackwell Publishing Ltd., 2004) Kunz, Dr. Andreas
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    Approximation of Optimal Voxel Size for Collision Detection in Maintainability Simulations within Massive Virtual Environments
    (The Eurographics Association and Blackwell Publishing Ltd., 2004) Borro, D.; Garcia-Alonso, A.; Matey, L.
    This paper describes a Collision Method for massive virtual environments composed of millions of triangles. It has been applied in the aeronautics industry for maintainability simulations using virtual aircraft engine mock-ups. The method performs well and has a good interactive frame rate even when it is used for computing force feedback with haptic devices. Space sorting problems chiefly related to voxel techniques, such as memory requirements and optimal voxel size, have been solved. We use advanced memory structures and hashing techniques. To find the optimal voxel size, several analytical solutions have been proposed and compared. These solutions are based on the performance cost function of the algorithm used. Experiments have been undertaken to verify these analytical solutions.
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    CGForum 2004 Cover Image
    (The Eurographics Association and Blackwell Publishing Ltd., 2004)
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    Cultural Heritage Preservation Using Constructive Shape Modeling
    (The Eurographics Association and Blackwell Publishing Ltd., 2004) Vilbrandt, C.; Pasko, G.; Pasko, A.; Fayolle, P.-A.; Vilbrandt, T.; Goodwin, J. R.; Goodwin, J. M.; Kunii, T. L.
    Issues of digital preservation of shapes and internal structures of historical cultural objects are discussed. An overview of existing approaches to digital preservation related to shape modeling is presented and corresponding problems are considered. We propose a new digital preservation paradigm based on both constructive modeling reflecting the logical structure of the objects and open standards and procedures. Constructive Solid Geometry (CSG) and Function Representation (FRep) are examined and practically applied as mathematical representations producing compressed yet precise data structures, thus providing inter-operability between current and future computer platforms crucial to archiving. Examples of CSG reconstruction of historical temples and FRep modeling of traditional lacquer ware are given. We examine the application of fitting of a parameterized FRep model to a cloud of data points as a step towards automation of the modeling process. Virtual venues for public access to cultural heritage objects including real time interactive simulation of cultural heritage sites over the Web are discussed and illustrated.
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    Editorial
    (2004)
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    Eurographics 2003
    (The Eurographics Association and Blackwell Publishing Ltd., 2004) Duce, David; Torres, Juan Carlos
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    Eurographics Symposium on Rendering 2003
    (The Eurographics Association and Blackwell Publishing Ltd., 2004) Lagae, Ares; Masselus, Vincent; Dutre, Philip
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    An Eye Gaze Model for Dyadic Interaction in an Immersive Virtual Environment: Practice and Experience
    (The Eurographics Association and Blackwell Publishing Ltd., 2004) Vinayagamoorthy, V.; Garau, M.; Steed, A.; Slater, M.
    This paper describes a behavioural model used to simulate realistic eye-gaze behaviour and body animations for avatars representing participants in a shared immersive virtual environment (IVE). The model was used in a study designed to explore the impact of avatar realism on the perceived quality of communication within a negotiation scenario. Our eye-gaze model was based on data and studies carried out on the behaviour of eye-gaze during face-to-face communication. The technical features of the model are reported here. Information about the motivation behind the study, experimental procedures and a full analysis of the results obtained are given in [17].
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    Fast Multipath Radiosity using Hierarchical Subscenes
    (The Eurographics Association and Blackwell Publishing Ltd., 2004) Castro, F.; Sbert, M.; Neumann, L.
    This paper presents an efficient acceleration technique for the global line radiosity Multipath method. In this approach, the scene is subdivided in a hierarchy of box bounded subscenes, the boxes subdivided in a grid of virtual patches which store angular information. A new recursive (according to the hierarchy of subscenes) function allows to execute the Multipath algorithm at different levels of the hierarchy. A speed up factor up to 3-4 has been obtained on some of the tested scenes.
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    Hardware Lighting and Shading: a Survey
    (The Eurographics Association and Blackwell Publishing Ltd., 2004) Kautz, Jan
    Traditionally, hardware rasterizers only support the Phong lighting model in combination with Gouraud shading using point light sources. However, the Phong lighting model is strictly empirical and physically implausible. Gouraud shading also tends to undersample the highlight unless a highly tesselated surface is used. Hence, higher-quality hardware accelerated lighting and shading has gained much interest in the recent five years. The research on hardware lighting and shading is two-fold. On the one hand, better lighting models for local illumination (assuming point light sources but evaluated per pixel) were demonstrated to be amenable to hardware implementation. On the other hand, recent research has demonstrated that even area lights, represented as environment maps, can be combined with complex lighting models. In both areas, many articles have been published, making it hard to decide which algorithm is well-suited for which application. This state-of-the-art report will review all relevent articles in both areas, and list advantages and disadvantages of each algorithm.
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    Implicit Fitting Using Radial Basis Functions with Ellipsoid Constraint
    (The Eurographics Association and Blackwell Publishing Ltd., 2004) Li, Q.; Wills, D.; Phillips, R.; Viant, W. J.; Griffiths, J. G.; Ward, J.
    Implicit planar curve and surface fitting to a set of scattered points plays an important role in solving a wide variety of problems occurring in computer graphics modelling, computer graphics animation, and computer assisted surgery. The fitted implicit surfaces can be either algebraic or non-algebraic. The main problem with most algebraic surface fitting algorithms is that the surface fitted to a given data set is often unbounded, multiple sheeted, and disconnected when a high degree polynomial is used, whereas a low degree polynomial is too simple to represent general shapes. Recently, there has been increasing interest in non-algebraic implicit surface fitting. In these techniques, one popular way of representing an implicit surface has been the use of radial basis functions. This type of implicit surface can represent various shapes to a high level of accuracy. In this paper, we present an implicit surface fitting algorithm using radial basis functions with an ellipsoid constraint. This method does not need to build interior and exterior layers for the given data set or to use information on surface normal but still can fit the data accurately. Furthermore, the fitted shape can still capture the main features of the object when the data sets are extremely sparse. The algorithm involves solving a simple general eigen-system and a computation of the inverse or psedo-inverse of a matrix, which is straightforward to implement.
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    Join Now!
    (2004)
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    Network Service
    (2004)
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    Prototype Modeling from Sketched Silhouettes based on Convolution Surfaces
    (The Eurographics Association and Blackwell Publishing Ltd., 2004) Tai, Chiew-Lan; Zhang, Hongxin; Fong, Jacky Chun-Kin
    This paper presents a hybrid method for creating three-dimensional shapes by sketching silhouette curves. Given a silhouette curve, we approximate its medial axis as a set of line segments, and convolve a linearly weighted kernel along each segment. By summing the fields of all segments, an analytical convolution surface is obtained. The resulting generic shape has circular cross-section, but can be conveniently modified via sketched profile or shape parameters of a spatial transform. New components can be similarly designed by sketching on different projection planes. The convolution surface model lends itself to smooth merging between the overlapping components. Our method overcomes several limitations of previous sketched-based systems, including designing objects of arbitrary genus, objects with semi-sharp features, and the ability to easily generate variants of shapes.
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    Second Annual Symposium on Computer Animation (SCA 2003)
    (The Eurographics Association and Blackwell Publishing Ltd., 2004) SCA 2003 Chairs
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    Symposium on Geometry Processing
    (The Eurographics Association and Blackwell Publishing Ltd., 2004) Kobbelt, Leif; Schoeder, Peter; Hoppe, Hugues
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    Volume Graphics 2003
    (The Eurographics Association and Blackwell Publishing Ltd., 2004) Fujishiro, Issei; Mueller, Klaus; Kaufman, Arie