排序方式: 共有78条查询结果,搜索用时 250 毫秒
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段先华 《华东船舶工业学院学报》2007,21(5):59-63
在分析直升机在天空飞行序列图像特点的基础上,提出了基于光流和水平集模型的运动目标自动跟踪方法。该方法通过对图像进行高通滤波预处理,获得运动目标的特征图像,用特征图像来求解运动目标的光流,用光流对运动区域进行分割,获得运动区域的中心和半径,以该中心和半径的圆作为初始水平集曲线,以光流速度作为曲线演化的外力修改Chan and Vese模型,用改进后的模型对图像进行分割。实验证明,用本文方法能够快速、准确地自动跟踪运动目标。 相似文献
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Jos de Jesús Salas Prez 《Journal of Marine Systems》2003,43(3-4):105-131
The westward evolution of an open-sea anticyclonic eddy along the western Algerian Basin is shown, for the first time, by means of 15 buoy trajectories and remote sensing observations. For 3 months, the buoy trajectories described several anticyclonic loops in periods of 4–21 days. The eddy's movement, translation, and rotation were separated with a kinematic model, resulting in a mean translation speed of 2 km/day, which fits the self-propulsion speed predicted on theoretical models for isolated eddies on a beta plane. Fluctuations in translation speed were associated with advection of the mean flow and topographic interactions. Both mechanisms changed the eddy's horizontal shape from circular to elliptical, inducing fluctuations in its swirl velocity and solid-body rotation. The initial stage of the eddy is an isolated asymmetric dipole, comprised by a small cyclone and a large anticyclone, the latter generated from a frontal instability, which under the Coriolis term acquires anticyclonic relative vorticity. During its first days of life, the anticyclonic eddy was shallow Ro=0.9 and small (diameter less than 50 km). Later on, it reached a diameter of 150 km and a vertical structure of 3 km (Ro=0.1). A retrospective analysis with infrared images shows that the eddy's generation took place at about 3–4°E. Then, the eddy completed a counterclockwise circuit never before reported in other studies and ended up at the entrance of the Algerian Basin, where the interaction with the topography and the coastal instability induced its decay. The eddy's life span was 10 months. Computations of the heating rate following clusters of buoy trajectories show fluctuations throughout the eddy's journey, induced by advection and a seasonal warming. 相似文献
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基于区域分割的非局部全变差SAR相干斑滤波 总被引:1,自引:1,他引:0
受成像体制影响,合成孔径雷达(Synthetic aperture radar,SAR)图像带有非高斯的乘性相干斑噪声。为有效抑制乘性相干斑噪声,提出一种融合非局部均值滤波(Non-local means filter, NLMF)与全变差(Total variation,TV)正则化的非局部均值-全变差(NLM-TV)降噪算法。首先将相干斑噪声转换为依赖于散射强度的加性噪声,将SAR图像分为边缘、强散射区、弱散射区。然后利用NLMF进行降斑,为有效的保持边缘结构, NLMF的平滑参数选取较小。在强散射区,为解决平滑参数较小所带来的降斑不充分问题,进一步使用TV正则化进行平滑处理,获得最终的降噪结果。使用RADARSAT-2,TerraSAR-X两景实测SAR图像仿真实验,结果表明:相比多种滤波算法, NLM-TV算法在弱散射区,强散射区均能显著提高等效视数,边缘保持指数能够提高10%以上。 相似文献
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本文研究的目的是探讨中外翻译中如何传达文化意象这个问题,采用的方法是从读者的能动性阅读,读者阅读经验变化以及文化意象的理解与替换方面入手,从中寻找让译本读者尽可能多的获取文本意象中负载的文化信息。其研究结果表明:加深文化交流将会使读者阅历发生变化,而读者阅历的改变又反过来促进文化交流的发展,并能更容易处理文学翻译中的文化差异。 相似文献
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基于各向异性测度的路面三维图像裂缝识别 总被引:2,自引:1,他引:1
为准确而完整地识别路面裂缝,提出了基于1 mm/像素的路面三维图像裂缝自动识别算法.该算法主要包括各向异性测度计算与自适应优化阈值分割、深度验证和多分辨率去噪处理3个部分.首先,针对路面图像像素特征,基于0°、45°、90°和135°四个方向的线性邻域的均值和标准差计算每个像素的各向异性测度(表征方向性的强弱),并应用最大类间方差法确定最优阈值,将路面图像分为强方向性和弱方向性像素两类;其次,根据半径为d的正方形邻域深度均值设定阈值,用方向性强且深度低于或等于该阈值的像素形成初步的裂缝图像;最后,将裂缝图像划分为多个子块,设计去噪模板对裂缝图像进行滑动窗口去噪处理,获得最终裂缝图像.基于166幅含有各类裂缝的三维路面图像(2048×2048像素)进行测试分析,结果显示,本文算法获得了较高的准确率(均值91.57%)和召回率(均值81.29%),最终以84.26%的F1均值优于种子识别算法(F1均值69.19%)、Canny边缘检测(F1均值8.15%)和OTSU分割(F1均值5.11%). 相似文献
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针对海事闭路电视(CCTV)系统未能直接通过视频图像获得海上目标位置信息的现状,提出一种基于航拍图像的海上目标定位系统.该系统基于Visual C++开发平台,以模块化设计思路,实现基于航拍图像的海上目标定位功能.介绍系统组成、主要功能、概位算法以及该定位系统在海事监管、海上搜救中的应用.该定位系统可弥补海事CCTV监管的不足,提升海事监管、海上搜救的效率. 相似文献
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The motion analysis of fire video images based on moment features and flicker frequency 总被引:2,自引:0,他引:2
In this paper, motion analysis methods based on the moment features and flicker frequency features for early fire flame from ordinary CCD video camera were proposed, and in order to describe the changing of flame and disturbance of non-flame phenomena further more, the average changing pixel number of the first-order moments of consecutive flames has been defined in the moment analysis as well. The first-order moments of all kinds of flames used in our experiments present irregularly flickering, and their average changing pixel numbers of first-order moments are greater than fire-like disturbances. For the analysis of flicker frequency of flame, which is extracted and calculated in spatial domain, and therefore it is computational simple and fast. The method of extracting flicker frequency from video images is not affected by the catalogues of combustion material and distance. In experiments, we adopted two kinds of flames, i.e. , fixed flame and movable flame. Many comparing and disturbing experiments were done and verified that the methods can be used as criteria for early fire detection. 相似文献
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