共查询到16条相似文献,搜索用时 62 毫秒
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在地形表达上不规则三角网应用广泛,实际中用到最多的也是Delaunay三角网剖分算法。针对约束数据域下的Delaunay三角剖分通常不满足DT特性的问题进行了阐述,分析了已有的三种引入附加点的算法,算法主要从几何的角度考虑如何减少附加点的数量,而加入附加点的最终目的在于获得更加真实的地形,因而提出了基于边界特征点提取的约束Delaunay三角剖分算法,算法实质就是在加入特征约束之前提取能够满足可以真实再现地形的所有特征点作为新的特征约束,省去附加点的概念,应用现有的Delaunay三角剖分算法进行构网,保证构建后的地形仍具真实感。 相似文献
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二维电磁态势是战场电磁态势研究的重要内容,是战场电磁频谱管控的重要依据.提出了一种改进的前沿边推进算法来构建Delaunay三角网,提高了Delaunay三角网的构网速度.通过等值点的插值、追踪、平滑处理和等值区的构造,实现了二维电磁态势的可视化.仿真结果表明,采用该方法绘制的二维电磁态势图速度较快. 相似文献
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覆盖问题是传感器网络研究中的一个基础课题,如何判定某个感兴趣的区域是否被一组给定的传感器节点覆盖,在传感器网络的许多监控应用领域中具有重要意义。提出了一种传感器网络中基于正三角形剖分的快速κ-覆盖判定算法和最大κ-覆盖问题的求解算法,新算法首先把感兴趣区域剖分为正三角形区域,从而将复杂的区域覆盖问题转化为简单的正三角形区域覆盖问题。理论分析与仿真实验表明,针对具有n个节点的传感器网络,新算法的计算时间复杂度为O(n),低于已有算法O(nlogn)的计算时间复杂度。 相似文献
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为减少网络GIS海量数字高程模型(Digital Elevation Model,DEM)数据的存储与传输数据量,提出一种编解码快速、压缩位流具有三种嵌入(分辨率嵌入、感兴趣区域嵌入和质量嵌入)特点的DEM无损压缩算法——DFC(DEM Fast Compression)算法。选用2/6可逆整数小波分解DEM数据,对变换系数的每级分辨率数据按照区域划分分区,对每个分区子带系数的每一个位面在一次扫描中完成简单高效的自适应游程Golomb_Rice编码。实验数据表明:比JPEG2000算法编码、解码时间分别减少了61.12%和56.23%,而压缩比仅仅降低了10.91%;比SPIHT算法编码、解码时间分别减少了58.83%和50.71%,而压缩比仅仅降低了7.54%;比GZIP压缩比平均提高了74.05%;比n点最优预测算法压缩比提高了5.83%。DFC算法在保持较好的压缩性能的同时,大幅度减少了编解码时间,并且在各级分辨率具有很好的精度性能。Abstract: To decrease DEM data volume for storage and transmission in net-GIS,the DFC (DEM Fast Compression) algorithm for DEM lossless compression was proposed,which has three embedded characters (resolution,region of interest,and fidelity).The 2/6 reversible integer wavelet was selected to decompose DEM data.Every resolution of the transform coefficients was partitioned into many precincts according to the area.In each sub-band of each precinct,only in one pass,the bits of every bit-plane were run-length encoded with adaptive Golomb_Rice coding which is very simple and effective.The experiments show that:compared with JPEG2000,DFC's encoding and decoding time decrease 61.12% and 56.23% respectively,while the compression ratio decreases only 10.91%;compared with SPIHT,DFC's encoding and decoding time decrease 58.83% and 50.71% respectively,while the compression ratio decreases only 7.54%;compared with GZIP,DFC's compression ratio increases 74.05%;compared with n neighbors' prediction algorithm,DFC's compression ratio increases 5.83%.Thus,the DFC algorithm decreases the coding and decoding time largely while maintains favorable compression performance,and has excellent accuracy performance in every resolution data. 相似文献
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Wireless sensor networks promise a new paradigm for gathering data via collaboration among sensors spreading over a large geometrical region. Many applications impose delay requirements for data gathering and ask for time-efficient schedules for aggregating sensed data and sending to the data sink. In this paper, the authors study the minimum data aggregation time problem under collision-free transmission model. In each time round, data sent by a sensor reaches all sensors within its transmission range, but a sensor can receive data only when it is the only data that reaches the sensor. The goal is to find the method that schedules data transmission and aggregation at sensors so that the time for all requested data to be sent to the data sink is minimal. The authors propose a 7△/log2|s|+c, new approximation algorithm for this NP-hard problem with guaranteed performance ratio which significantly reduces the current best ratio of △- 1, where S is the set of sensors containing source data, A is the maximal number of sensors within the transmission range of any sensor, and e is a constant. The authors also conduct extensive simulation, the obtained results justify the improvement of proposed algorithm over the existing one. 相似文献
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本文通过引进神经元增益参数和记忆上一次网络状态改变量的冲量参数,设计了BPGA,对标准的BP算法进行了改进,提高了网络的学习速度和收敛性,并与标准的BP算法进行了比较. 相似文献
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Xiaoming Zhao Xijian Ye Shenzhou Zheng 《系统科学与信息学报》2006,4(4):697-703
Rafael C. Gnzalez has mentioned an algorithm on adaptive local noise elimination filter in the book named Digital Image Processing. This paper points out the algorithm's deficiency and presents an improved harmonic mean filter algorithm which makes mean square error emse cutting quarter but SNR, SNPm and PSNR increasing a tenth more than original algorithm. This filter algorithm is verified to be effective by simulation experiment. 相似文献
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秦振华 《系统工程与电子技术》1998,(1)
快速卡尔曼算法是递推最小二乘算法中的一种,它的收敛速度比梯度算法快得多,其计算量又比常规卡尔曼算法少得多,特别适合于跟踪像电离层这样的快变化时变信道。本文对用于自适应均衡的快速卡尔曼算法进行了详细研究。 相似文献