Volume 21 (2002)

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Browsing Volume 21 (2002) by Title

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    12th Eurographics Workshop on Rendering
    (Blackwell Publishers Ltd and the Eurographics Association, 2002)
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    13th Eurographics Workshop on Rendering
    (Blackwell Publishers, Inc and the Eurographics Association, 2002) Debevec, Paul; Gibson, Simon
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    1st Ibero-American Symposium in Computer Graphics
    (Blackwell Publishers, Inc and the Eurographics Association, 2002) Marcos, Aderito; Brunet, Pere; Jorge, Joaquim; Regincos, Jordi
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    22nd EUROGRAPHICS General Assembly
    (Blackwell Publishers Ltd and the Eurographics Association, 2002)
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    23rd Eurographics General Assembly
    (Blackwell Publishers, Inc and the Eurographics Association, 2002)
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    The 3D Model Acquisition Pipeline
    (Blackwell Publishers Ltd and the Eurographics Association, 2002) Bernardini, Fausto; Rushmeier, Holly
    Three-dimensional (3D) image acquisition systems are rapidly becoming more affordable, especially systems based on commodity electronic cameras. At the same time, personal computers with graphics hardware capable of displaying complex 3D models are also becoming inexpensive enough to be available to a large population. As a result, there is potentially an opportunity to consider new virtual reality applications as diverse as cultural heritage and retail sales that will allow people to view realistic 3D objects on home computers.Although there are many physical techniques for acquiring 3D data-including laser scanners, structured light and time-of-flight-there is a basic pipeline of operations for taking the acquired data and producing a usable numerical model. We look at the fundamental problems of range image registration, line-of-sight errors, mesh integration, surface detail and color, and texture mapping. In the area of registration we consider both the problems of finding an initial global alignment using manual and automatic means, and refining this alignment with variations of the Iterative Closest Point methods. To account for scanner line-of-sight errors we compare several averaging approaches. In the area of mesh integration, that is finding a single mesh joining the data from all scans, we compare various methods for computing interpolating and approximating surfaces. We then look at various ways in which surface properties such as color (more properly, spectral reflectance) can be extracted from acquired imagery. Finally, we examine techniques for producing a final model representation that can be efficiently rendered using graphics hardware.
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    3D Scanning Technology: Capabilities and Issues
    (Blackwell Publishers, Inc and the Eurographics Association, 2002) Scopigno, Roberto
    The recent evolution of graphics technology makes it possible to manage very complex models on inexpensive platforms. These impressive rendering capabilities should be paired with detailed and accurate digital models. The construction of high quality 3D models is made easier by the increasing diffusion of automatic 3D measuring devices (often called 3D scanners). These allow to build highly accurate models of real 3D objects in a cost- and time-effective manner. The talk will present the capabilities of this technology focusing mainly on a particular application context: the acquisition of Cultural Heritage artifacts. The peculiar requirements of this domain (high accuracy in the acquisition of both shape and surface appearance, expected low cost and easiness of use of the tools) make it a perfect application example. This talk aims also at presenting and discussing the main issues in the acquisition of accurate 3D models, together with some limitations of current hardware and software tools. Some examples of the results of current projects will be shown.
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    3rd Eurographics Workshop on Parallel Graphics and Visualization
    (Blackwell Publishers Ltd and the Eurographics Association, 2002)
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    6th Eurographics Workshop on Multimedia
    (Blackwell Publishers Ltd and the Eurographics Association, 2002)
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    An Adaptive Sampling Scheme for Out-of-Core Simplification
    (Blackwell Publishers Ltd and the Eurographics Association, 2002) Fei, Guangzheng; Cai, Kangying; Guo, Baining; Wu, Enhua
    Current out-of-core simplification algorithms can efficiently simplify large models that are too complex to be loaded in to the main memory at one time. However, these algorithms do not preserve surface details well since adaptive sampling, a typical strategy for detail preservation, remains to be an open issue for out-of-core simplification. In this paper, we present an adaptive sampling scheme, called the balanced retriangulation (BR), for out-of-core simplification. A key idea behind BR is that we can use Garland's quadric error matrix to analyze the global distribution of surface details. Based on this analysis, a local retriangulation achieves adaptive sampling by restoring detailed areas with cell split operations while further simplifying smooth areas with edge collapse operations. For a given triangle budget, BR preserves surface details significantly better than uniform sampling algorithms such as uniform clustering. Like uniform clustering, our algorithm has linear running time and small memory requirement.
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    Adaptive Zooming in Web Cartography
    (Blackwell Publishers, Inc and the Eurographics Association, 2002) Cecconi, Alesandro; Galanda, Martin
    Beyond any doubt much of the current web mapping and web GIS applications lack cartographic quality. Thereasons aren't only the technical limitations related to Internet delivery, but also the neglect of one of the maincartographic principles of digital mapping, namely adaptive zooming. Adaptive zooming describes the adjustmentof a map, its contents and the symbolization to target scale in consequence of a zooming operation. The approachdescribed in this paper proposes the combination of two commonly known concepts: on the one hand levelsof detail (LoD) for those object classes, that require high computational cost for the automated generalizationprocess (e.g. buildings, road network); on the other hand an on-the-fly generalization for those object classeswhich can be generalized by less complex methods and algorithms (e.g. rivers, lakes). Realizing such interactiveand dynamic concept for web mapping requires the use of vector based visualization tools. The data format bestmeeting the criteria is the W3C standard Scalable Vector Graphics (SVG). Thus, it has been used to implementthe presented ideas in a prototype application for topographic web mapping based on the landscape modelVECTOR25 of the Swiss Federal Office of Topography.
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    Advanced Radiance Estimation For Photon Map Global Illumination
    (Blackwell Publishers, Inc and the Eurographics Association, 2002) Hey, Heinrich; Purgathofer, Werner
    We present a new method to compute radiance in photon map based global illumination simulation for polygonal scenes with general bidirectional scattering distribution functions (BSDFs). Our new radiance estimation uses the actual geometry in the neighborhood of the illuminated point, and does not assume that the nearest neighbor photons lie in the same plane as the point, nor that they are distributed in a circular area around that point. This allows us to achieve accurate indirect illumination by direct visualization of the photon map - which is especially important for the simulation of caustics(LS+DS*Epaths) - even in the vicinity of edges and corners of objects, and on surfaces with differently oriented small geometric details.
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    An algorithm for line clipping against a polygon based on shearing transformation
    (Blackwell Publishers, Inc and the Eurographics Association, 2002) Huang, Y. Q.; Liu, Y. K.
    Line clipping against a polygon is widely used in computer graphics such as the hidden line problem. A newline-clipping algorithm against a general polygon is presented in this paper. The basic idea of this algorithm is tochange the line to be clipped into a horizontal line by shearing transformation. Then each edge of the polygonalwindow is transformed by a shearing transformation with the same parameters as those used to the line. Eachedge of the polygon is processed against a horizontal line, which makes the clipping process simpler. The result inthis paper shows that less calculation is needed for the new algorithm with a higher speed compared to existingalgorithms.
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    Angle-Analyzer: A Triangle-Quad Mesh Codec
    (Blackwell Publishers, Inc and the Eurographics Association, 2002) Lee, Haeyoung; Alliez, Pierre; Desbrun, Mathieu
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    Artificial Animals and Humans: From Physics to Intelligence
    (Blackwell Publishers, Inc and the Eurographics Association, 2002) Terzopoulos, Demetri
    The confluence of virtual reality and artificial life, an emerging discipline that spans the computational and biological sciences, has yielded synthetic worlds inhabited by realistic, artificial flora and fauna. Artificial animals are complex synthetic organisms that possess functional biomechanical bodies, sensors, and brains with locomotion, perception, behavior, learning, and cognition centers. Artificial humans and other animals are of interest in computer graphics because they are self-animating characters that dramatically advance the state of the art of production animation and interactive game technologies. More broadly, these biomimetic autonomous agents in their realistic virtual worlds also foster deeper, computationally oriented insights into natural living systems.
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    Artistic Surface Rendering Using Layout of Text
    (Blackwell Publishers Ltd and the Eurographics Association, 2002) Surazhsky, Tatiana; Elber, Gershon
    An artistic rendering method of free-form surfaces with the aid of half-toned text that is laid-out on the given surface is presented. The layout of the text is computed using symbolic composition of the free-form parametric surface S(u, v) with cubic or linear Bezier curve segments C(t) = cu (t), cv (t), comprising the outline of the text symbols. Once the layout is constructed on the surface, a shading process is applied to the text, affecting the width of the symbols as well as their color, according to some shader function. The shader function depends on the surface orientation and the view direction as well as the color and the direction or position of the light source.
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    Auditor's Report
    (2002)
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    Author Index Volume 21 (2002)
    (Blackwell Publishers, Inc and the Eurographics Association, 2002)
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    Automatic Integration of Facade Textures into 3D Building Models with a Projective Geometry Based Line Clustering
    (Blackwell Publishers, Inc and the Eurographics Association, 2002) Lee, Sung Chun; Jung, Soon Ki; Nevatia, Ram
    Visualization of city scenes is important for many applications including entertainment and urban mission planning. Models covering wide areas can be efficiently constructed from aerial images. However, only roof details are visible from aerial views; ground views are needed to provide details of the building facades for high quality 'fly-through' visualization or simulation applications. We present an automatic method of integrating facade textures from ground view images into 3D building models for urban site modeling. We first segment the input image into building facade regions using a hybrid feature extraction method, which combines global feature extraction with Hough transform on an adaptively tessellated Gaussian Sphere and local region segmentation. We estimate the external camera parameters by using the corner points of the extracted facade regions to integrate the facade textures into the 3D building models. We validate our approach with a set of experiments on some urban sites.Categories and Subject Descriptors (according to ACM CCS): I.3.3 [Computer Graphics]: Modeling packages
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    A Biologically-Parameterized Feather Model
    (Blackwell Publishers, Inc and the Eurographics Association, 2002) Streit, L.; Heidrich, W.
    Feathers, unlike other cutaneous appendages such as hair, fur, or scales have a definite structure. Variation in feather structure creates a wide range of resulting appearances. Collectively, feather structure determines the appearance of the feather coat, which can largely affect the resulting look of a feathered object (bird). In this paper we define the structure of individual feathers using a parameterization based on biological structure and substructures of actual feathers. We show that our parameterization can generate a large variety of feathers at multiple levels of detail and provide an initial step to semi-automatically generating a wide range of feather coats. his is achieved by specifying an intuitive interpolation between different structures and ages of feathers.