We are proposing a multiresolution representation which uses a subdivision surface as a smooth base surface with respect to which a high resolution mesh is defined by normal displacement. While this basic representati...
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We are proposing a multiresolution representation which uses a subdivision surface as a smooth base surface with respect to which a high resolution mesh is defined by normal displacement. While this basic representation is quite straightforward, our actual contribution ties in the automatic generation of such a representation. Given a high resolution mesh, our algorithm is designed to derive a subdivision control mesh whose structure is properly adjusted and aligned to the major geometric features. This implies that the control vertices of the subdivision surface not only control globally smooth deformations but in addition that these deformations are meaningful in the sense that their support and shape correspond to the characteristic structure of the input mesh. This is achieved by using a new decimation scheme for general polygonal meshes (not just triangles) that is based on face merging instead of edge collapsing. A face-based integral metric makes the decimation scheme very robust such that we can obtain extremely coarse control meshes which in turn allow for deformations with large support.
Quasi-developable mesh segmentation is required,for many applications in graphics and CAD, including texture atlas generation and the design of patterns for model fabrication from sheets of material. In this work we i...
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Quasi-developable mesh segmentation is required,for many applications in graphics and CAD, including texture atlas generation and the design of patterns for model fabrication from sheets of material. In this work we introduce D-Charts, a simple and robust algorithm for mesh segmentation into (nearly) developable charts. As part of our method we introduce a new metric of developability for mesh surfaces. Thanks to this metric, using our segmentation for texture atlas generation, we can bound the distortion of the atlas directly during the segmentation stage. We demonstrate that by using this bound, we generate more isometric atlases for the same number of charts compared to existing state-of-the-art techniques. Using our segmentation algorithm we also develop a technique for automatic pattern design. To demonstrate the practicality of this technique, we use the patterns produced by our algorithm to make fabric and paper copies of popular computer graphics models.
For the linear MIMO plants subject to polyharmonic perturbations, a method of designing digital state controllers was developed with regard for the requirements oil limitedness of the control actions in the stable sta...
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For the linear MIMO plants subject to polyharmonic perturbations, a method of designing digital state controllers was developed with regard for the requirements oil limitedness of the control actions in the stable state as well as oil limitedness of the controlled variables. A notion of radius of the stable state of a closed-loop system was introduced, and the problem of using the full state vector to design a discrete controller providing the desired radius was formulated. Its necessary and sufficient solvability conditions were obtained using the procedure of H-infinity-optimization by selecting the weight matrices of the discrete Lur'e-Riccati equation.
A robust output feedback tracking strategy for uncertain nonlinear systems with output measurement noise is presented by using a passivity approach. The control algorithm guarantees boundedness of all the signals in t...
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A robust output feedback tracking strategy for uncertain nonlinear systems with output measurement noise is presented by using a passivity approach. The control algorithm guarantees boundedness of all the signals in the whole closed-loop system. Tracking accuracy can be reduced to a desirable bound. A simulation example is included to demonstrate effectiveness of the proposed algorithm.
The number of 3D geometric models available in online repositories is growingdramatically. Examples include: the Protein Data Bank, which stores the 3D atomic coordinates for29,000 protein molecules; the National Desi...
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The number of 3D geometric models available in online repositories is growingdramatically. Examples include: the Protein Data Bank, which stores the 3D atomic coordinates for29,000 protein molecules; the National Design Repository, which stores 3D computer-aided design(CAD) models for tens of thousands of mechanical parts; and the Princeton Shape Database, whichstores polygonal surface models for 36,000 everyday objects crawled from the Web. Since graphicshardware is getting faster and 3D scanning hardware cheaper, there is every reason to believe thatdemand for and supply of 3D models will continue to increase into the future, leading to an onlineenvironment in which 3D models are as plentiful as images, videos, and audio files today.
An iterative algorithm to determine the optimal control of a discrete system with two types of controllers was proposed. It has several realization versions, which enhances its adjustability to particular problems. It...
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An iterative algorithm to determine the optimal control of a discrete system with two types of controllers was proposed. It has several realization versions, which enhances its adjustability to particular problems. Its application to optimization of the regional development strategy was discussed.
The authors propose a window-based congestion control algorithm to achieve max-min fair sharing of the available bandwidth in ECN capable heterogeneous TCP networks. The proposed algorithm extracts the network status ...
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The authors propose a window-based congestion control algorithm to achieve max-min fair sharing of the available bandwidth in ECN capable heterogeneous TCP networks. The proposed algorithm extracts the network status from successive binary congestion information provided by ECN. From the extracted network information, the authors estimate a fair window size proportional to the propagation delay. Through simulations, the effect on TCP fairness of the proposed algorithm is shown for the heterogeneous network.
The recent development of communication theory and radio technology has intensified interest in multi-antenna systems as an effective technique to combat fading of the desired signal, tackle interference from other si...
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The recent development of communication theory and radio technology has intensified interest in multi-antenna systems as an effective technique to combat fading of the desired signal, tackle interference from other signals, and increase the data rate in wireless communications. This article provides a survey of downlink processing algorithms for multi-antenna systems. The understanding of fundamental downlink processing strategies is extremely important in analyzing the future of high-capacity/high-quality wireless communications.
The point set is a flexible surface representation suitable for both geometry processing and real-time rendering. In most applications, the control of the point cloud density is crucial and being able to refine a set ...
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The point set is a flexible surface representation suitable for both geometry processing and real-time rendering. In most applications, the control of the point cloud density is crucial and being able to refine a set of points appears to be essential. In this paper we present a new interpolatory refinement framework for point-based geometry. First we carefully select an appropriate one-ring neighborhood around the central interpolated point. Then new points are locally inserted where the density is too low using a root 3-like refinement procedure and they are displaced on the corresponding curved Point Normal triangle. Thus, a smooth surface is reconstructed by combining the smoothing property produced by the rotational effect of root 3-like refinements with the points/normal interpolation of PN triangles. In addition we show how to handle sharp features and how our algorithm naturally fills large holes in the geometry. Finally, we illustrate the robustness of our approach, its real-time capabilities and the smoothness of the reconstructed surface on a large set of input models, including irregular and sparse point clouds.
An anchoring theory of lightness perception comprehensively explains many characteristics of human visual system such as lightness constancy and its spectacular failures which are important in the perception of images...
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An anchoring theory of lightness perception comprehensively explains many characteristics of human visual system such as lightness constancy and its spectacular failures which are important in the perception of images. We present a novel approach to tone mapping of high dynamic range (HDR) images which is inspired by the anchoring theory. The key concept of this method is the decomposition of an HDR image into areas (frameworks) of consistent luminance and the local calculation of the lightness values. The net lightness of an image is calculated via the merging of the frameworks proportionally to their strength. We stress out the importance of relating the luminance to a known brightness value (anchoring) and investigate the advantages of anchoring to the luminance value perceived as white. We validate the accuracy of the lightness reproduction in the presented algorithm by simulating a well known perception experiment. Our approach does not affect the local contrast and preserves the natural colors of an HDR image due to the linear handling of luminance.
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