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61.
In this paper, we present a method for reconstructing a surface mesh animation sequence from point cloud animation data. We mainly focus on the articulated body of a subject — the motion of which can be roughly described by its internal skeletal structure. The point cloud data is assumed to be captured independently without any inter‐frame correspondence information. Using a template model that resembles the given subject, our basic idea for reconstructing the mesh animation is to deform the template model to fit to the point cloud (on a frame‐by‐frame basis) while maintaining inter‐frame coherence. We first estimate the skeletal motion from the point cloud data. After applying the skeletal motion to the template surface, we refine it to fit to the point cloud data. We demonstrate the viability of the method by applying it to reconstruct a fast dancing motion  相似文献   
62.
介绍了城域光传输网络的基本概念和组网结构,归纳了浙江省城域光传输网的建设现状。以此为基础,简要地总结了城域光传输网从环状网络向网状网络的演进趋势以及城域光网建设的规划原则。  相似文献   
63.
Traffic information acquisition system is an essential part of the intelligent transportation system (ITS). This paper presents a novel traffic information acquisition system, i.e., a dynamic traffic information acquisition system based on wireless mesh networks (WMN). The system comprises of probe vehicles and wireless mesh networks. Compared to the conventional systems, it is independent of other network infrastructures and easy to implement. It can acquire the real-time traffic information correctly with lower cost.  相似文献   
64.
Wireless mesh networks (WMNs) have been proposed to provide cheap, easily deployable and robust Internet access. The dominant Internet-access traffic from clients causes a congestion bottleneck around the gateway, which can significantly limit the throughput of the WMN clients in accessing the Internet. In this paper, we present MeshCache, a transparent caching system for WMNs that exploits the locality in client Internet-access traffic to mitigate the bottleneck effect at the gateway, thereby improving client-perceived performance. MeshCache leverages the fact that a WMN typically spans a small geographic area and hence mesh routers are easily over-provisioned with CPU, memory, and disk storage, and extends the individual wireless mesh routers in a WMN with built-in content caching functionality. It then performs cooperative caching among the wireless mesh routers.We explore two architecture designs for MeshCache: (1) caching at every client access mesh router upon file download, and (2) caching at each mesh router along the route the Internet-access traffic travels, which requires breaking a single end-to-end transport connection into multiple single-hop transport connections along the route. We also leverage the abundant research results from cooperative web caching in the Internet in designing cache selection protocols for efficiently locating caches containing data objects for these two architectures. We further compare these two MeshCache designs with caching at the gateway router only.Through extensive simulations and evaluations using a prototype implementation on a testbed, we find that MeshCache can significantly improve the performance of client nodes in WMNs. In particular, our experiments with a Squid-based MeshCache implementation deployed on the MAP mesh network testbed with 15 routers show that compared to caching at the gateway only, the MeshCache architecture with hop-by-hop caching reduces the load at the gateway by 38%, improves the average client throughput by 170%, and increases the number of transfers that achieve a throughput greater than 1 Mbps by a factor of 3.  相似文献   
65.
This paper proposes a new digital beamformer for uniform concentric spherical array (UCSA) having nearly frequency invariant (FI) characteristics. The basic principle is to transform the received signals to the phase mode and remove the frequency dependency of the individual phase mode through the use of a digital beamforming network. It is shown that the far field pattern of the array is determined by a set of weights and it is approximately invariant over a wide range of frequencies. FI UCSAs are electronic steerable in both the azimuth and elevation angles, unlike their concentric circular array counterpart. The frequency invariant characteristic of the FI UCSA also makes it possible to design separately the compensation network and beamformer weighting coefficients. The design of the compensation network is formulated as a second order cone programming (SOCP) problem and is solved optimally for minimax criterion. Thanks to the frequency invariant characteristic, traditional narrow band adaptive beamforming algorithms such as minimum variance beamforming (MVB) can be applied to the FI UCSA. Also, traditional narrow band 2-D direction of arrival (DOA) estimation algorithms such as unitary ESPRIT can be extended to broadband DOA estimation using FI UCSA. Simulation results show that the proposed adaptive beamformer using FI UCSA can obtain a higher output signal to inference plus noise ratio over the conventional tapped-delay line approach. Simulation results also show that FI UCSA has uniform beampattern and resolution around 360° in both azimuth and elevation angles, unlike FI uniform concentric circular array. The usefulness of the proposed UCSA-FIB in broadband 2-D DOA estimation is also verified by computer simulation.
H. H. ChenEmail:
  相似文献   
66.
针对大视场视觉监控的应用,提出了一种基于球面坐标的双目主动视觉传感器协同跟踪方法。首先采用图像特征匹配的方法估计摄像机的内部参数,然后引入球面经纬坐标系作为双目视觉传感器的公共坐标系,最后结合场景深度范围实现目标的协同跟踪。对于任意安装的双目视觉传感器,提出了一种建立球面公共坐标系的新方法,统一了不同参数下的情形,可以实现任意参数下的协同跟踪。实际监控场景下的视频实验,验证了方法的有效性和可行性。  相似文献   
67.
Since a large field of view obviously bears important advantages, the use of spherical images is becoming increasingly important in various computer vision and image processing applications. This paper presents a novel rotation estimation approach for spherical images based on 3D mesh representation of gray level intensity. Once the 3D meshes of the underlying spherical images are obtained, the 3D rotation can be estimated directly and efficiently, without feature extraction and matching process. Subsequently, we propose a direct method for 3D object rotation estimation using spherical harmonics representation with SVD decomposition and ICP algorithm for estimation refinement. Experimental results validate our approach and prove its suitability and robustness for rotation estimation. Moreover, it performs well against noisy images, brightness changes, image compression and occlusions. A comparative study of our proposed approach with four similar methods for 3D rotation estimation between spherical images, is realized to prove its effectiveness.  相似文献   
68.
脉冲光栅展宽器受共焦望远镜系统球差影响的解析分析   总被引:1,自引:1,他引:1  
周士安  钱列加 《中国激光》2000,27(6):519-524
提出一种近似的方法 ,其考虑具有望远镜系统的光栅展宽器的有效光栅间距 ,以补偿球差。给出二阶色散和四阶色散的修正量公式。据此 ,可得出对实验元件性能的具体要求。  相似文献   
69.
A large-scale high-precision scan stage is important equipment in the industrial productions of micro-fabrication such as flat panel display (FPD) lithography systems. Designing controllers for multi-input multi-output (MIMO) systems is time-consuming and needs experience because of the interaction between each axis and many controller tuning parameters. The aim of this study is to develop a peak filter design method based on frequency response data to reduce repetitive disturbance. This data-based approach does not use the model and only uses the frequency response data of the controlled system and the disturbance spectrum calculated from the scanning error data (Contribution 1). The peak filter is designed by convex optimization and satisfies robust stability conditions for six-degree-of-freedom systems (Contribution 2). The control performance of the designed peak filter is experimentally demonstrated with an industrial MIMO large-scale high-precision scan stage in reducing the scanning error of the main stroke of the translation along the x-axis (Contribution 3).  相似文献   
70.
提出了一种基于选播的无线Mesh网络网关选取模型和相应的网关选取路由算法。该模型将所有网关节点抽象成一个选播组,将所有的网关节点组成一个网关树,实现对网关组成员的管理与维护。网关选取路由算法以时延为度量,通过有效的选播机制自适应地查找"最优"网关节点为客户节点服务,以提供响应最快的高质量的因特网接入服务。实验结果表明,该算法能在合理的时间内有效地解决多网关选取问题。  相似文献   
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