In this paper we investigate the ability of the mean shift (MS) algorithm for denoising of 3D computer Tomography (CT) data sets. The large size of the volume data sets makes it infeasible to apply a 3D version of the...
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Recently developed 3D scanning devices are capable of capturing point clouds, as well as additional information, such as normals and texture. This paper describes a new and fast reverse engineering method for creating...
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Recently developed 3D scanning devices are capable of capturing point clouds, as well as additional information, such as normals and texture. This paper describes a new and fast reverse engineering method for creating a 3D computerized model from data captured by such contemporary 3D scanning devices. The proposed method aggregates large-scale 3D scanned data into an extended Hierarchical Space Decomposition Model (HSDM) based on Octree data structure. This model can represent both an object's boundary surface and its interior volume. The HSDM enables data reduction, while preserving sharp geometrical features and object topology. As a result the execution time of the reconstruction process is significantly reduced. Moreover, the proposed model naturally allows multiresolution surface reconstruction, represented by a mesh with regular properties. Based on the proposed volumetric model, the surface reconstruction process becomes, more robust and stable with respect to sampling noise.
Feature modeling systems usually employ a boundary representation (b-rep) to store the shape information on a product. It has, however, been shown that a b-rep has a number of shortcomings, and that a cellular model c...
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Feature modeling systems usually employ a boundary representation (b-rep) to store the shape information on a product. It has, however, been shown that a b-rep has a number of shortcomings, and that a cellular model can be a valuable alternative. A cellular model stores additional shape information on a feature, including the faces that are not on the boundary of the product. Such information can be profitably used for several purposes. A major operation in each feature modeling system is boundary evaluation, which computes the geometric model of a product, i.e. either the b-rep or the cellular model, from the features that have been specified by the user. Because it has to be executed each time a feature has been added, removed or modified, its efficiency is very important. In this paper, boundary evaluation for a cellular model is described. Subsequently, its efficiency is compared to the efficiency of boundary evaluation for a b-rep, on the basis of performance measurements and considerations for both. It turns out that boundary evaluation for a cellular model is in fact more efficient than for a b-rep, which makes cellular models even more attractive as an alternative for b-reps.
We consider the fractional prize-collecting Steiner tree problem on trees. This problem asks for a subtree T containing the root of a given tree G = (V,E) maximizing the ratio of the vertex profits (Formula Presented)...
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Vector field visualization aims at generating images in order to convey the information existing in the data. We use Markov Random Field (MRF) texture synthesis methods to generate the visualization from a set of samp...
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We present a classification of attacks against digital audio watermarks and possible countermeasures. We present the categorization of attacks into the four different groups of removal, desynchronization, embedding an...
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We present a classification of attacks against digital audio watermarks and possible countermeasures. We present the categorization of attacks into the four different groups of removal, desynchronization, embedding and detection attacks. The logic behind this arrangement is based on the effect the attack should produce during the detection of the audio watermark and is discussed in detail. For each class of attacks an exhaustive explanation is provided with corresponding links to other media types. If countermeasures are known for the attacks they are described in each group.
Non-linear filtering is an important task for volume analysis. This paper presents hardware-based implementations of various non-linear filters for volume smoothing with edge preservation. The Cg high-level shading la...
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Non-linear filtering is an important task for volume analysis. This paper presents hardware-based implementations of various non-linear filters for volume smoothing with edge preservation. The Cg high-level shading language is used in combination with latest PC consumer graphics hardware. Filtering is divided into pervertex and per-fragment stages. In both stages we propose techniques to increase the filtering performance. The vertex program pre-computes texture coordinates in order to address all contributing input samples of the operator mask. Thus additional computations are avoided in the fragment program. The presented fragment programs preserve cache coherence, exploit 4D vector arithmetic, and internal fixed point arithmetic to increase performance. We show the applicability of non-linear filters as part of a GPU-based segmentation pipeline. The resulting binary mask is compressed and decompressed in the graphics memory on-the-fly.
Volumetric samples on Cartesian lattices are less ef_cient than samples on body-centred cubic (BCC) lattices. We show how to construct isosurfaces on BCC lattices using several different algorithms. Since the mesh tha...
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This paper presents a work that is part of the system for creation of real-faced avatar for emphatic communication. We have made a new extension of the KL T (Kanade-Lucas-Tomasi) face tracker. which is robust against ...
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ISBN:
(纸本)9789549641332
This paper presents a work that is part of the system for creation of real-faced avatar for emphatic communication. We have made a new extension of the KL T (Kanade-Lucas-Tomasi) face tracker. which is robust against loss of the tracked points. Stochastic skin-color model is used for a face segmentation in the frames contained in a video sequence. Ellipse-fitting is used for selection of the face candidates because of the elliptical face shape. The proposed method achieved real-time performance The results seem very promising.
In this paper, a system named IVS (Interactive Virtual Studio), which integrates low-level (feature extraction and ordering), mid-level (camera parameters estimation and evaluation), high-level (object recognition and...
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In this paper, a system named IVS (Interactive Virtual Studio), which integrates low-level (feature extraction and ordering), mid-level (camera parameters estimation and evaluation), high-level (object recognition and reconstruction), and graphics techniques, is presented. The purpose of IVS is to integrate computer generated animation with real image sequence seamlessly. With minimum human intervention, IVS is an off-line postprocessing system that operates on a real world sequence in which a known object is tracked. The camera pose in each frame is recovered from which the camera trajectory is reconstructed. Firstly, object features are extracted from the environment and correspondence between the extracted shape and a shape from a database is solved by an SVD (Singular Value Decomposition) based technique. Secondly, SFSM (Structure from Simulated Motion) is used for object recognition and the information is used for reconstruction of the 3D object contained in the image. An evaluation mechanism is introduced to provide feedback and reduce the registration error. In the last stage of the processing, virtual graphics objects are imported to interact with the real image sequence. While the concept of developing such a system is not new, the various novel techniques we incorporated into IVS make it different.
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