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Now showing 1 - 10 of 590
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    Fast Continuous Collision Detection among Deformable Models using Graphics Processors
    (The Eurographics Association, 2006) Govindaraju, Naga K.; Kabul, Ilknur; Lin, Ming C.; Manocha, Dinesh; Ming Lin and Roger Hubbold
    We present an interactive algorithm to perform continuous collision detection between general deformable models using graphics processors (GPUs). We model the motion of each object in the environment as a continuous path and check for collisions along the paths. Our algorithm precomputes the chromatic decomposition for each object and uses visibility queries on GPUs to quickly compute potentially colliding sets of primitives. We introduce a primitive classification technique to perform efficient continuous self-collision. We have implemented our algorithm on a 3:0 GHz Pentium IV PC with a NVIDIA 7800 GPU, and we highlight its performance on complex simulations composed of several thousands of triangles. In practice, our algorithm is able to detect all contacts, including self-collisions, at image-space precision in tens of milli-seconds.
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    Constellation Models for Sketch Recognition
    (The Eurographics Association, 2006) Sharon, Dana; Panne, Michiel van de; Thomas Stahovich and Mario Costa Sousa
    Sketch-based modeling shares many of the difficulties of the branch of computer vision that deals with single image interpretation. Most obviously, they must both identify the parts observed in a given 2D drawing or image.We draw on constellation models first proposed in the computer vision literature to develop probabilistic models for object sketches, based on multiple example drawings. These models are then applied to estimate the most-likely labels for a new sketch. A multi-pass branch-and-bound algorithm allows well-formed sketches to be quickly labelled, while still supporting the recognition of more ambiguous sketches. Results are presented for five classes of objects.
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    Efficient Sorting and Searching in Rendering Algorithms
    (The Eurographics Association, 2006) Havran, Vlastimil; Bittner, Jiri; Nadia Magnenat-Thalmann and Katja Bühler
    In the proposed tutorial we would like to highlight the connection between rendering algorithms and sorting and searching as classical problems studied in computer science. We will provide both theoretical and empirical evidence that for many rendering techniques most time is spent by sorting and searching. In particular we will discuss problems and solutions for visibility computation, density estimation, and importance sampling. For each problem we mention its specific issues such as dimensionality of the search domain or online versus offline searching. We will present the underlying data structures and their enhancements in the context of specific rendering algorithms such as ray shooting, photon mapping, and hidden surface removal.
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    HOPI: A Novel High Order Parametric Interpolation in 2D
    (The Eurographics Association, 2006) Xu, Jia; Huang, Zhiyong; Dieter Fellner and Charles Hansen
    This paper presents a novel smooth and convergent high order parametric interpolation method called HOPI with a formal treatment. It employs high order derivatives information and provides more freedom on control of curves. It can be applied to shape design and analysis using curves. This paper reports the work in 2D.
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    WWW-Based Building Information System for "Domus Severiana" Palace at Palatine in Rome by Open Source Software
    (The Eurographics Association, 2006) Heine, Katja; Brasse, Christiane; Wulf, Ulrike; Marinos Ioannides and David Arnold and Franco Niccolucci and Katerina Mania
    The aim of this research project is the digital documentation of the "Domus Severiana" Palace at Palatine in Rome through the integration of geometrical 3D- and non-geometrical information. The great density of information requires an efficient concept of data storage and management and an adequate means of presentation of high quality. The decision was made to develop a www-based information system based mainly on open source software modules. Linux, Apache, MySQL and PHP as well as VRML-data format as open source components, were used for the information system; only the construction of the 3D-geometrical model was realized by means of commercial software. The 3D-model shows the different construction phases and depicts the reconstruction ideas at the respective different construction phases. Above all the 3D-model is the basis of joining the building information system to other sources of information, available in databases: the digital "Raumbuch", which contains all non-geometric information about the several rooms, archives of plans, drawings and photos, catalogues of the devices, brick stamps and constructions, as well as keys to literature and archives. The data storage, management and analysis are the central tasks of the project; realistic visualisation is secondary.
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    Use of Shader Technology for Realistic Presentation of Train Prototypes in Virtual Reality
    (The Eurographics Association, 2006) Gironimo, G. Di; Papa, S.; S. Battiato and G. Gallo and F. Stanco
    The aim of the paper is to make up a virtual showroom and work-through of a train model in order to allow railway companies showing new trains prototypes, in phase of concept, and present their new design in more exhaustive way than simply technical documentation. The possibility of applying Virtual Reality (VR) methodologies to make a scene more realistic as possible is a great advantage for the effectiveness of the presentation, in order to increase their competitivity. Shader technology allows the programmers to have control over shape, appearance (such as colour, lighting, reflection) and animation of objects, in order to make very realistic real-time rendering. In the paper the authors describe the use of shader technology in Virtual Design 2 (VD2) for realistic presentation of train prototypes in VR. The software VD2 is an extensive tool that allows following many phases of product development, from the creation of showroom for realistic presentations supporting shader technology to the assembly simulation or ergonomics analysis. Moreover, the possibility of interfacing with a wide range of input/output devices and the possibility to access to the API made this software to be chosen for Virtual Reality applications in the VR laboratory of the Competence Center for the Qualification of Transportation Systems founded by Campania Region (www.centrodicompetenzatrasporti.unina.it).
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    A Natural and Effective Calibration of the CyberGlove
    (The Eurographics Association, 2006) Partipilo, S.; Felice, F. De; Renna, F.; Attolico, G.; Distante, A.; S. Battiato and G. Gallo and F. Stanco
    This work addresses the calibration of the CyberGlove, a device which provides information about the position and attitude in space of all the components of the user hand in a haptic system for the fruition of digital 3D contents by blind people. A realistic haptic interaction requires a reliable detection of user movements and a good calibration of the device to account for size and articulation capability of the specific hand. At the same time the application of interest calls for a calibration procedure that should be executable in a natural and straightforward way by every user. The two methods provided by the CyberGlove software are not suitable for these purposes: one is very simple and fast but produces quite imprecise results while the other is effective and accurate but involves a complex and cumbersome trial-and-error process not suited for general users. The proposed method aims to reach satisfactory results using a intuitive and simple approach. The user is asked to assume with his hand several pre-defined poses, each supplying the sensors output associated to known joints angles. Combining these data with the constraints derived by the anatomical structure of the hand it is possible to evaluate the values of the two parameters, gain and offset, that drive the digitalization of the sensor output. This process, in spite of its simplicity, has provided satisfactory results in several experimental sessions, enabling a realistic and reliable mirroring of user movements in the virtual space.
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    Animating Shapes at Arbitrary Resolution with Non-Uniform Stiffness
    (The Eurographics Association, 2006) Nesme, Matthieu; Payan, Yohan; Faure, François; Cesar Mendoza and Isabel Navazo
    We present a new method for physically animating deformable shapes using finite element models (FEM). Contrary to commonly used methods based on tetrahedra, our finite elements are the bounding voxels of a given shape at arbitrary resolution. This alleviates the complexities and limitations of tetrahedral volume meshing and results in regular, well-conditionned meshes. We show how to build the voxels and how to set the masses and stiffnesses in order to model the physical properties as accurately as possible at any given resolution. Additionally, we extend a fast and robust tetrahedron-FEM approach to the case of hexahedral elements. This permits simulation of arbitrarily complex shapes at interactive rates in a manner that takes into account the distribution of material within the elements.
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    A Randomized Approach for Patch-based Texture Synthesis using Wavelets
    (The Eurographics Association and Blackwell Publishing Ltd, 2006) Tonietto, L.; Walter, M.; Jung, C. R.
    We present a wavelet-based approach for selecting patches in patch-based texture synthesis. We randomly select the first block that satisfies a minimum error criterion, computed from the wavelet coefficients (using 1D or 2D wavelets) for the overlapping region. We show that our wavelet-based approach improves texture synthesis for samples where previous work fails, mainly textures with prominent aligned features. Also, it generates similar quality textures when compared against texture synthesis using feature maps with the advantage that our proposed method uses implicit edge information (since it is embedded in the wavelet coefficients) whereas feature maps rely explicitly on edge features. In previous work, the best patches are selected among all possible using a L2 norm on the RGB or grayscale pixel values of boundary zones. The L2 metric provides the raw pixel-to-pixel difference, disregarding relevant image structures - such as edges - that are relevant in the human visual system and therefore on synthesis of new textures.
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    Unambiguous Analysis of Woman Breast Shape for Plastic Surgery Outcome Evaluation
    (The Eurographics Association, 2006) Farinella, G. M.; Impoco, G.; Gallo, G.; Spoto, S.; Catanuto, G.; S. Battiato and G. Gallo and F. Stanco
    This paper reports a multidisciplinary research between computer science and plastic and reconstructive surgery. In particular, a new method is proposed to unambiguously define a geometric partitioning of a large thoracic area including the breast mound. The new technique uses only well-defined anatomical points, defined and selected by surgeons. A simple sequence of geometric operations is performed to partition the breast surface into four anatomic subunits, according to clinically derived breast meridian and equator lines. Using this breast shape partition, useful measurement can be extrapolated on 3D model data set. Our method has been validated on a number of breast 3D models acquired by means of a commercial scanner on real clinical cases collected by Istituto Nazionale dei Tumori in Milan (INT).