The Mediazine is a distributed interactive multimedia magazine for the Internet including text, applications, images, live audio, live-video, animations, 3D comp.ter graphics. Users and Actors can interactively meet e...
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ISBN:
(纸本)1581133030
The Mediazine is a distributed interactive multimedia magazine for the Internet including text, applications, images, live audio, live-video, animations, 3D comp.ter graphics. Users and Actors can interactively meet each other in a shared virtual environment that is distributed via comp.ter network. The system uses high quality multimedia streams. For the playback of audio an own developed Spatial Audio Server is used. On one hand it provides output for the communication system, an Internet-Telephone. On the other hand it manages sound of applications like TV and radio. Additionally spatialized binaural output is provided for the sound: In the virtual environment participants speech the can be located from where their avatars are placed. The participant'S sound is coming from the place where the video is presented. The paper describes how the system is built. It focuses on the mechanism of controlling the amount and quality of multimedia information on behalf of the network and the receiver system. Furthermore, the paper discusses how agents can be integrated as comp.nents in the system that is organized as an object-oriented application framework. Authors can take advantage of this concept specifying the agent'S behavior efficiently in a target domain specific way. Finally, a prototype implementation of the mediazine system is presented.
Visualization and collision detection are two of the most important problems connected with implicit objects. Enumeration algorithms can be used either directly or as preprocessing step for many algorithms solving the...
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ISBN:
(纸本)9781581136081
Visualization and collision detection are two of the most important problems connected with implicit objects. Enumeration algorithms can be used either directly or as preprocessing step for many algorithms solving these problems. In general, enumeration algorithms based on recursive space subdivision are reliable tools to encounter those parts in space, where the object might be located. But the bad performance and the huge number of comp.ted enclosing cells, if high precision is required, are grave drawbacks. Implicit Linear Interval Estimations (ILIEs) introduced in this paper are implicit interval (hyper-)planes providing oriented tight bounds of the object within given cells. It turns out that the use of ILIEs highly improves the performance of the classical enumeration algorithm and the quality of the results. The theoretical background as well as a fast and simple technique to comp.te ILIEs are presented. The applicability of ILIEs is demonstrated by means of a modified enumeration algorithm that has been implemented and tested for implicit surfaces.
The classification of volumetric data sets as well as their rendering algorithms are typically based on the representation of the underlying grid. Grid structures based on a Cartesian lattice are the de-facto standard...
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The classification of volumetric data sets as well as their rendering algorithms are typically based on the representation of the underlying grid. Grid structures based on a Cartesian lattice are the de-facto standard for regular representations of volumetric data. In this paper we introduce a more general concept of regular grids for the representation of volumetric data. We demonstrate that a specific type of regular lattice - the so-called body-centered cubic - is able to represent the same data set as a Cartesian grid to the same accuracy but with 29.3% fewer samples. This speeds up traditional volume rendering algorithms by the same ratio, which we demonstrate by adopting a splatting implementation for these new lattices. We investigate different filtering methods required for comp.ting the normals on this lattice. The lattice representation results also in lossless comp.ession ratios that are better than previously reported. Although other regular grid structures achieve the same sample efficiency, the body-centered cubic is particularly easy to use. The only assumption necessary is that the underlying volume is isotropic and band-limited - an assumption that is valid for most practical data sets.
We consider the generalized assignment problem in which the objective is to find a minimum cost assignment of a set of jobs to a set of agents subject to resource constraints. The presented new approach is based on a ...
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ISBN:
(纸本)9781581138122
We consider the generalized assignment problem in which the objective is to find a minimum cost assignment of a set of jobs to a set of agents subject to resource constraints. The presented new approach is based on a previously published, successful hybrid genetic algorithm and includes as new features two alternative initialization heuristics, a modified selection and replacement scheme for handling infeasible solutions more appropriately, and a heuristic mutation operator. Tests are performed on standard test inst.nces from the literature and on newly created, larger and more difficult inst.nces. The presented genetic algorithm with its two initialization variants is comp.red to the previous genetic algorithm and to the commercial general purpose branch-and-cut system CPLEX. Results indicate that CPLEX is able to solve relatively large inst.nces of the general assignment problem to provable optimality. For the largest and most difficult inst.nces, however, the proposed genetic algorithm yields on average the best results in shortest time.
In this paper, we present a data model for 3D geometry and topology in a 3D-GIS. This data model includes the concept of multiple representations for the same feature. Together with a spatial index, these multiple rep...
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In this paper an interactive volume rendering technique is presented which is based on a novel visualization model. We call the basic method "bubble model" since iso-surfaces are rendered as thin semi-transp...
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In this paper an interactive volume rendering technique is presented which is based on a novel visualization model. We call the basic method "bubble model" since iso-surfaces are rendered as thin semi-transparent membranes similarly to blown soap bubbles. The primary goal is to develop a fast previewing technique for volumetric data which does not require a time-consuming transfer function specification to visualize internal structures. Our approach uses a very simple rendering model controlled by only two parameters. We also present an interactive rotation technique which does not rely on any specialized hardware, therefore it can be widely used even on lowend machines. Due to the interactive display, fine tuning is also supported since the modification of the rendering parameters has an immediate visual feedback.
The use of frequency output for measurement transmission remains common in the design of smart transmitters. Conventional methods of frequency generation, based on counting clock cycles, have a precision which is inve...
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The use of frequency output for measurement transmission remains common in the design of smart transmitters. Conventional methods of frequency generation, based on counting clock cycles, have a precision which is inversely proportional to the frequency to be generated. Consequently, frequency output precision could be much lower than the measurement precision. This paper describes a simple frequency generation technique which, when implemented in low-cost hardware, provides a precision of 10-6 per cent for all frequencies. The method represents an intermediate non-available frequency by dithering between two exact frequencies. Averaging over some reasonably short timescale provides the desired frequency to high precision.
Normal vector discontinuities on surfaces provide important visual cues for understanding the image of a geometrical object since they often indicate feature boundaries. We present an algorithm that preserves the appe...
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ISBN:
(纸本)9781581136081
Normal vector discontinuities on surfaces provide important visual cues for understanding the image of a geometrical object since they often indicate feature boundaries. We present an algorithm that preserves the appearance of features in view-dependent multiresolution meshes. The algorithm is shown to be efficient in terms of time and memory consumption. Our method is comp.tible with geomorphing to eliminate popping artefacts in interactive applications, and it can also be applied to texture coordinates. A large set of examples demonstrates the benefits of the proposed algorithm.
We present a method that allows to identify individual objects in a view-dependent multiresolution triangle mesh. Unlike previous methods, where the input mesh was considered a uniform "triangle soup", our m...
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ISBN:
(纸本)158113861X
We present a method that allows to identify individual objects in a view-dependent multiresolution triangle mesh. Unlike previous methods, where the input mesh was considered a uniform "triangle soup", our method enables passing of object semantics through the process of encoding, transmission, and decoding. This information can be used on the client side to query additional data to a specific part of the mesh. Moreover, it allows a part of the mesh to be transformed (e.g., moved to a different location for better inspection) within the multiresolution framework of adaptive refinement. Finally we show that the overhead introduced by our method is negligible. The algorithm has been tested with artifically and manually created data and with models acquired within the digital archaeology project "3D MURALE".
We propose two mechanisms that can be used to generate comp.ex geometry: generalized subdivision and mesh-based parametrized L-Systems. inst.ad of using standard subdivision, which uses the same subdivision rule at ea...
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We propose two mechanisms that can be used to generate comp.ex geometry: generalized subdivision and mesh-based parametrized L-Systems. inst.ad of using standard subdivision, which uses the same subdivision rule at each level of the subdivision process, in order to converge to a limit surface, we employ a generalized approach, that allows different subdivision rules at each level. By limiting the variations at each level, it is possible to ensure convergence. Mesh-based parametrized L-Systems represent an extension to L-systems which associates symbols to the faces in a mesh. Thereby comp.ex geometry can be introduced into an existing mesh by using procedural substitution rules. Combining both these mechanisms, a wide variety of comp.ex models can be easily generated from very comp.ct representations.
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