In this paper we present a novel LOD based rendering approach that integrates geometry based and image based LOD mechanisms in one system. We assume that every LOD object in the scene is represented by a textured poly...
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In this paper we present a novel LOD based rendering approach that integrates geometry based and image based LOD mechanisms in one system. We assume that every LOD object in the scene is represented by a textured polygonal mesh. In a preprocess we generate a continuous multiresolution model for all LOD objects. During runtime we first check for every LOD object if an appropriate cached approximation generated for former frames is available. If not, we extract a new suitable approximation out of the objects continuous multiresolution model depending on view-dependent criteria. After that, we replace this adaptive geometry-based approximation by an image-based impostor if this is reasonable and efficient. The selected approximations of LOD objects are used for rendering the next frame
Triangle surface models belong to the most popular type of geometric objects description in computergraphics. Therefore, the problem of fast visualization of this type of data is often solved. One of popular approach...
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Triangle surface models belong to the most popular type of geometric objects description in computergraphics. Therefore, the problem of fast visualization of this type of data is often solved. One of popular approaches is stripification, i.e., a conversion of triangle surface into strips of triangles. This enables to reduce the rendering time by reduction data size and by avoiding of redundant lighting and transformations computations. In this paper we present a new stripification algorithm for static fully triangulated meshes. Our new algorithm is based on the dual graph of triangulation. The experimental results show that our stripification produces much lower number of triangle strips than other stripification algorithms (except one)
Digital Particle Image Velocimetry (PIV) is an optical technique used to measure the velocity of seeded particles in real flow. A CCD camera captures the flow field twice under exposure to a short duration laser flash...
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ISBN:
(纸本)3898380580
Digital Particle Image Velocimetry (PIV) is an optical technique used to measure the velocity of seeded particles in real flow. A CCD camera captures the flow field twice under exposure to a short duration laser flash. Recorded image pairs are cross-correlated to extract velocity information from these records. Time resolved PIV technology can capture images with some hundreds of frames per second. In this paper, we present a PIV-system that implements vector field reconstruction and visualization on programmable graphics processing units (GPUs) thus providing a high-speed back-end for time resolved PIV technology. We propose an efficient FFT implementation on such hardware, which is used to cross-correlate multiple pairs of interrogation windows. To visualize extracted vector fields we employ functionality to create and to render geometry data on the GPU. In this way, not only can any data transfer between the CPU and the GPU be avoided, but spatial information derived from PIV as well as the time history of points in the flow can be combined instantaneously.
This paper presents a fast haptic rendering method providing the sense of touch from a virtual volumetric non-rigid object when a human operator interacts with the object at multiple points. Previously, we have propos...
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ISBN:
(纸本)0769521126
This paper presents a fast haptic rendering method providing the sense of touch from a virtual volumetric non-rigid object when a human operator interacts with the object at multiple points. Previously, we have proposed a fast volume haptic rendering method based on the shape-retaining chain linked model (or the S-chain model) that can handle the deformation of a volumetric non-rigid object and its haptic feedback in real time. One of the key differences between the S-chain model and a traditional FEM or mass-spring model is that the computation of the deformation and its reflected force is performed at a local level. When there are more than one interaction points with the object, it is necessary to consider a modeling framework that can handle human operator's all inputs together. In this paper, we propose a modeling framework in which forces generated at interaction points are vectorially summed to deal with the multiple contact points. Our experiments demonstrate that our proposed method is suitable for the real-time volume haptic rendering of a volumetric non-rigid object with multiple-contact points.
The importance of contextual knowledge in knowledge management and organizational memory is shown in topical literature. Even in an initial visionary scenario for the Semantic Web, one can immediately encounter the co...
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The importance of contextual knowledge in knowledge management and organizational memory is shown in topical literature. Even in an initial visionary scenario for the Semantic Web, one can immediately encounter the contextual knowledge needed to realize the necessary services. Hence, it is not inappropriate to claim that context management is an integral service of the Semantic Web. After discussing the distributed nature of contextual knowledge, we define some requirements for a context-oriented database service and then introduce CORD as a service satisfying those requirements based on the Semantic Web technologies. Selected features of CORD that provide some contribution to the discussions within the Semantic Web research community, like embedded resources, query language, and definition of rules, are discussed in some detail.
Graph and tree visualization techniques enable interactive exploration of complex relations while communicating topology. However, most existing techniques have not been designed for situations where visual informatio...
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A survey of graphics developers on the issue of texture mapping hardware for volume rendering would most likely find that the vast majority of them view limited texture memory as one of the most serious drawbacks of a...
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A survey of graphics developers on the issue of texture mapping hardware for volume rendering would most likely find that the vast majority of them view limited texture memory as one of the most serious drawbacks of an otherwise fine technology. In this paper, we propose a compression scheme for static and time-varying volumetric data sets based on vector quantization that allows us to circumvent this limitation. We describe a hierarchical quantization scheme that is based on a multiresolution covariance analysis of the original field. This allows for the efficient encoding of large-scale data sets, yet providing a mechanism to exploit temporal coherence in non-stationary fields. We show, that decoding and rendering the compressed data stream can be done on the graphics chip using programmable hardware. In this way, data transfer between the CPU and the graphics processing unit (GPU) can be minimized thus enabling flexible and memory efficient real-time rendering options. We demonstrate the effectiveness of our approach by demonstrating interactive renditions of Gigabyte data sets at reasonable fidelity on commodity graphics hardware.
Nowadays, direct volume rendering via 3D textures has positioned itself as an efficient tool for the display and visual analysis of volumetric scalar fields. It is commonly accepted, that for reasonably sized data set...
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Nowadays, direct volume rendering via 3D textures has positioned itself as an efficient tool for the display and visual analysis of volumetric scalar fields. It is commonly accepted, that for reasonably sized data sets appropriate quality at interactive rates can be achieved by means of this technique. However, despite these benefits one important issue has received little attention throughout the ongoing discussion of texture based volume rendering: the integration of acceleration techniques to reduce per-fragment operations. In this paper, we address the integration of early ray termination and empty-space skipping into texture based volume rendering on graphical processing units (GPU). Therefore, we describe volume ray-casting on programmable graphics hardware as an alternative to object-order approaches. We exploit the early z-test to terminate fragment processing once sufficient opacity has been accumulated, and to skip empty space along the rays of sight. We demonstrate performance gains up to a factor of 3 for typical renditions of volumetric data sets on the ATI 9700 graphics card.
We discuss techniques for the visualization of medical volume data dedicated for their clinical use. We describe the need for rapid dynamic interaction facilities with such visualizations and discuss emphasis techniqu...
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Model-based reconstruction methods are applied to the detailed reconstruction of buildings from close-range images. The 3D points obtained through image matching are segmented into a coarse polyhedral model with a rob...
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Model-based reconstruction methods are applied to the detailed reconstruction of buildings from close-range images. The 3D points obtained through image matching are segmented into a coarse polyhedral model with a robust regression algorithm, then the geometry of this model is refined with predefined shape templates in order to automatically recover a CAD-like model of the building surface. Reprojection of the 3D shape templates is used to optimally fit their parameters to the image information. Throughout the paper the investigated methods are demonstrated on real datasets.
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