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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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.
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".
The Earth is still rather "flat". Therefore geographic data still tend to be two-dimensional and are stored in 2-dimensional information systems. But we do live in a three-dimensional world. In technical sys...
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ISBN:
(纸本)158113861X
The Earth is still rather "flat". Therefore geographic data still tend to be two-dimensional and are stored in 2-dimensional information systems. But we do live in a three-dimensional world. In technical systems, the 3rd dimension has long been merely an attribute of 2-dimensional graphical data. This is subject to rapid change. Three-dimensional models of the human habitat are emerging. The required tools to create and use such models are the topic of the paper. This is at the intersection of comp.ter graphics and comp.ter vision and reflects a recent trend in comp.ter science, where vision and graphics increasingly tend to meet. The paper discusses procedures for a fully automated creation of 3-dimensional models of today's buildings and cities, but also of interior spaces, even of microscopic worlds and of the lost cities of the antique. Methods will be described, but also their performance, accuracies, limitations and costs, to better understand what it takes to create and use a "virtual habitat".
Present-day technical infrastructures and appliances provide aplenty of opportunities for simplifying and supporting the everyday life. However, many of the systems available today - such as typical feature loaded mul...
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ISBN:
(纸本)0889863806
Present-day technical infrastructures and appliances provide aplenty of opportunities for simplifying and supporting the everyday life. However, many of the systems available today - such as typical feature loaded multimedia or infotainment systems - are not always efficiently usable for the average person. This paper presents a planning-based approach to helping the user to control such comp.ex infrastructures. It describes the architectural concept, which makes it possible to integrate classical Artificial Intelligence technology - such as planning and scheduling - into the domain of networked consumer appliances, like multimedia systems and room control. Especially, we concentrate on the architectural concepts, which allows us to create systems that can be extended dynamically and that are not build by a single vendor.
This paper presents an efficient volume measurement method for quantitative assessments within a virtual liver surgery planning system. The measurement is carried out by hardware-accelerated voxelization of surface-ba...
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ISBN:
(纸本)158113861X
This paper presents an efficient volume measurement method for quantitative assessments within a virtual liver surgery planning system. The measurement is carried out by hardware-accelerated voxelization of surface-based models in order to be applicable for interactive applications. The focus of this paper is the presentation of our voxelization technique suitable for off-the-shelf PC graphics cards including two different data retrieval approaches. Moreover, the measurement can be performed off-screen while not disturbing the rest of the application. Another important issue discussed in this paper is the applicability study within the planning system. Our measurement toolkit has been applied on several medical objects and delivers interactive response times.
Two planar triangulations with a correspondence between two vertex sets are comp.tible (isomorphic) if they are topologically equivalent. This work presents a simple and robust method for morphing two comp.tible plana...
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Two planar triangulations with a correspondence between two vertex sets are comp.tible (isomorphic) if they are topologically equivalent. This work presents a simple and robust method for morphing two comp.tible planar triangulations with identical convex boundaries that locally preserves the intrinsic geometric properties of triangles throughout the morph. The method is based on the barycentric coordinates representation of planar triangulations, and thus, guarantees comp.tibility of all intermediate triangulations. The intrinsic properties are preserved by interpolating angles and edge lengths comp.nents of mean value barycentric coordinates, rather than interpolating the barycentric coordinates themselves. As a result, the method generates a natural-looking and guaranteed intersection-free morphing sequence.
Given a connected, weighted, undirected graph G and a bound D, the bounded-diameter minimum spanning tree problem seeks a spanning tree on G of lowest weight in which no path between two vertices contains more than D ...
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ISBN:
(纸本)9781581136241
Given a connected, weighted, undirected graph G and a bound D, the bounded-diameter minimum spanning tree problem seeks a spanning tree on G of lowest weight in which no path between two vertices contains more than D edges. This problem is NP-hard for 4 ≤ D
This paper presents several strategies to interactively explore 3D flow. Based on a fast illuminated streamlines algorithm, standard graphics hardware is sufficient to gain interactive rendering rates. Our approach do...
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ISBN:
(纸本)158113861X
This paper presents several strategies to interactively explore 3D flow. Based on a fast illuminated streamlines algorithm, standard graphics hardware is sufficient to gain interactive rendering rates. Our approach does not require the user to have any prior knowledge of flow features. After the streamlines are comp.ted in a short preprocessing time, the user can interactively change appearance and density of the streamlines to further explore the flow. Most important flow features like velocity or pressure not only can be mapped to all available streamline appearance properties like streamline width, material, opacity, but also to streamline density. To improve spatial perception of the 3D flow we apply techniques based on animation, depth cueing, and halos along a streamline if it is crossed by another streamline in the foreground. Finally, we make intense use of focus+context methods like magic volumes, region of interest driven streamline placing, and spotlights to solve the occlusion problem.
Triangle mesh decimation and multi-resolution techniques are widely used in visualization applications for huge scenes. A large collection of different simplification algorithms exists hi order to build a multi-resolu...
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Triangle mesh decimation and multi-resolution techniques are widely used in visualization applications for huge scenes. A large collection of different simplification algorithms exists hi order to build a multi-resolution model from a given triangle mesh. All of the existing approaches focus on the creation of a geometrically close approximation of the original model. In order to produce a simplified version of a model with close layers such as dressed humans - self-intersections result in intolerable results. Even methods that allow the sewing of close surface parts lead to unpleasant self-intersections. Only the simplification envelops4 allow to comp.etely prevent them. In this work we focus on the prevention and avoidance of self-intersection during simplication with vertex pair contractions. We examine the geomorph 9 of the parametrized vertex pair contraction and detect collisions of the affected simplices. If no collision arises the operation cannot cause any new self-intersection. Otherwise we can simply discard the operation to prevent self-intersections as is done in the approach of simplification envelops. Our approach goes even further and tries to avoid the self-intersection by testing different target locations. This leads to better approximations as exhibited by a lower RMS and Hausdorff-distance. Furthermore our approach allows for arbitrary changes in the topology and garantees that geomorphs during progressive reception cannot cause self-intersections.
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