共查询到20条相似文献，搜索用时 15 毫秒
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一种新的SAR图像船只检测方法 总被引：7，自引：1，他引：7
提出一种新的基于恒虚警率(CFARConstantFalseAlarmRate)技术,确定SAR图像中检测船只整体阈值的方法。该方法采用高斯分布(正态分布)作为SAR图像灰度的概率密度函数,由CFAR技术直接导出用于检测船只整体阈值的计算公式,用记数滤波器滤波去除虚警。该算法避免了复杂公式迭代和求解形状参数计算过程,也避免了用二分法寻找阈值的循环解算过程,提高了检测速度。使用XSAR和ERSSAR图像对该算法进行检验,并与其它算法进行比较,结果显示所提出的算法在检测精度和检测速度上都有明显的改进。 相似文献
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Phase unwrapping is a key problem not only in all quantitative applications of synthetic aperture radar (SAR) interferometry but also in other fields. In this letter, a new phase unwrapping approach is investigated. Our study is based on the model of the optimum data vector. In order to autocoregister the SAR images, the proposed method takes advantage of the multibaseline optimal weighted joint data vector by extracting all the coherence information available in the neighboring pixels. Moreover, the method employs the projection of the joint signal subspace onto the corresponding noise subspace to estimate the unwrapped interferometric phases (or the terrain heights). The proposed method can accurately determine the dimensions of the noise subspace and provide the robust unwrapped interferometric phases even in the presence of the large image coregistration errors. Moreover, the multibaseline processing idea is a combination of data optimization, image coregistration, interferogram filtering, and phase unwrapping. 相似文献
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《Geoscience and Remote Sensing Letters, IEEE》2008,5(4):615-619
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针对目前SAR干涉测量中基线估计现存的问题,提出了利用Kalman滤波和配准参数进行基线估计的方法.所提出的方法具有不需地面控制点、不受地形限制和不依赖于轨道参数等优点,并可以估计时变的基线参数.利用南京地区的ERS-1/2 tandem数据进行了试验研究,并对提出的方法进行了验证.结果表明,在精确的卫星轨道数据和地面控制点不能获取时,所提出的方法仍能有效地估计InSAR基线.这在一定程度上补偿了轨道偏移带来的误差,为获取高精度的DEM奠定了基础. 相似文献
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针对全极化合成孔径雷达Pol SAR(Polarimetric Synthetic Aperture Radar)影像相干斑噪声严重的问题,提出了一种结合相似块匹配和线性最小均方误差原理的去噪方法。该方法首先在原始影像上实现相似块组的匹配,进而利用线性最小均方误差滤波器对影像块组进行滤波得到初始去噪结果;然后,同时利用原始影像和初始去噪影像的信息进行相似块组的重新匹配,并再次利用线性最小均方误差原理对重匹配影像块进行去噪,得到影像最终的去噪结果。利用模拟的Pol SAR影像和高分三号卫星Pol SAR影像进行了算法效果的验证。结果表明,去噪算法在显著抑制影像噪声水平的同时,也能较好地保持影像的边缘和极化特性等细节信息。 相似文献
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Using SAR Images to Detect Ships From Sea Clutter 总被引：4，自引：0，他引：4
Mingsheng Liao Changcheng Wang Yong Wang Liming Jiang 《Geoscience and Remote Sensing Letters, IEEE》2008,5(2):194-198
An innovative constant false alarm rate (CFAR) algorithm was studied for ship detection using synthetic aperture radar (SAR) images of the sea. Two advances were achieved. An alpha-stable distribution rather than a traditional Weibull or -distribution was used to model the distribution of sea clutter. The distribution of sea clutter in a SAR image was typically heterogeneous, caused mainly by variable wind and current conditions. Image segmentation was carried out to improve the homogeneity of the distribution in each subimage or region. In comparison with ship detection using the CFAR algorithms based on the Weibull or K -distribution, our algorithm detected the most number of ships with the smallest number of false alarms. 相似文献
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Unsupervised Change Detection From Multichannel SAR Images 总被引：1，自引：0，他引：1
Multichannel synthetic aperture radar (SAR) data present a good potential for environmental monitoring and disaster management, owing both to their insensitivity to atmospheric and sun-illumination conditions, and to the improved discrimination capability they may provide as compared to single-channel SAR. However, this requires accurate and possibly automatic techniques to generate change maps from multichannel SAR images acquired from the same geographic area at different times. In this letter, an automatic unsupervised contextual change-detection method is proposed for two-date multichannel SAR images, by integrating a SAR-specific extension of the Fisher transform with a variant of the expectation-maximization algorithm and with Markov random fields. The method is validated by experiments on SIR-C/XSAR data 相似文献
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全极化合成孔径雷达影像(PolSAR)相对单极化SAR影像有更加丰富的地表信息。为了提高SAR影像偏移量跟踪技术估算偏移量的精度,提出一种基于最小二乘平差法的全极化SAR数据偏移量估计方法。首先利用全极化SAR不同极化通道数据估算偏移量得到多个观测值,然后通过最小二乘平差法对多余观测值循环剔除粗差得到最优偏移量。文中选取美国科罗拉多州湖城(Lake city)区域的两景JPL无人机UAVSAR全极化SAR影像进行实验,结果表明,文中新方法具有良好的粗差探测和去除功能,相对于已有研究结果,在方位向和距离向的偏移量估算精度都有明显提高,达到15%~25%。新方法提高了偏移量跟踪估算偏移量的精度,这对利用偏移量跟踪技术监测滑坡、地震及冰川等有重要的意义。 相似文献
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相干斑的存在严重降低了全极化合成孔径雷达(polarimetric synthetic aperture radar,PolSAR)的影像质量,对相干斑进行抑制是使用PolSAR数据必不可少的预处理程序。本文提出了一种迭代优化的PolSAR非局部均值去噪方法。该方法在每次迭代去噪过程中,通过同时考虑原始影像全极化噪声统计特性和前一次迭代所得影像的全极化信息来完善像素间极化相似性的度量,从而实现对影像更精准的估计。试验部分利用模拟的PolSAR数据和真实的PolSAR影像进行了算法效果的验证。结果表明:去噪算法在显著抑制影像噪声水平的同时,也能较好地保持影像的边缘和极化特性等细节信息。 相似文献
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Tong Wang Zheng Bao 《Geoscience and Remote Sensing Letters, IEEE》2006,3(3):297-301
As we know, a multiple-aperture radar carried by a group of formation-flying satellites can be used to improve the coverage and azimuth resolution of spaceborne synthetic aperture radar (SAR) simultaneously. However, in the case of the reconstruction of azimuth signal from a periodic nonuniform sampling sequence, the sidelobe clutter and noise may be amplified by tens of decibels in some cases, which makes the final SAR image blurry. In this letter, we present the analytical result of the amplification factor of sidelobe clutter and noise for the evaluation of the reconstruction performance. According to the result, we propose a method to reduce the sidelobe clutter and noise, which considerably improves the quality of SAR image. Computer simulation results confirm the effectiveness of the method. 相似文献
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In this paper, a novel change detection approach is proposed for multitemporal synthetic aperture radar (SAR) images. The approach is based on two difference images, which are constructed through intensity and texture information, respectively. In the extraction of the texture differences, robust principal component analysis technique is used to separate irrelevant and noisy elements from Gabor responses. Then graph cuts are improved by a novel energy function based on multivariate generalized Gaussian model for more accurately fitting. The effectiveness of the proposed method is proved by the experiment results obtained on several real SAR images data sets. 相似文献
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船只检测是实现船只航行安全的重要措施之一,利用SAR图像可实现船只检测。然而,传统的一些方法一般容易受到SAR图像斑噪的影响,在检测结果中产生大量的虚警。为解决这一问题,本文提出了一种基于引力场增强的舰船检测方法。该方法利用像素与其邻域内像素的相互作用可对目标像素增强的效应,有效地抑制了斑噪像素和背景像素的强度,凸显了目标。由于增强后的像素已经不满足对海面区域的均质性假设,因此直接使用恒虚警检测算法对图像进行全局检测并不能够得到很好的效果,据此本文引入了一个基于均质区域自适应分割的改进的K-CFAR检测算法,将图像分割为不同大小的一系列均质区域,并分别对各个均质区域使用一个改进的K-CFAR检测器对船只目标进行检测。最后,使用Radarsat-1数据和Envisat ASAR数据对本文算法进行了验证。实验表明,本文提出的方法能够有效地凸显弱目标,增加检测准确性,降低检测的虚警概率。 相似文献
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Sahel Mahdavi Bahram Salehi Cecilia Moloney Weimin Huang Brian Brisco 《International Journal of Digital Earth》2018,11(7):703-729
Speckle degrades the radiometric quality of a Synthetic Aperture Radar (SAR) image. Previous methods for speckle reduction have used a fixed-size window for filtering the entire image. This, however, may not be effective for the entire image, as land covers of different sizes require different filtering windows. In this paper, a novel method is proposed by which each pixel in the image is filtered with a window appropriate for the size of object within it. The real in-phase and the imaginary quadrature components of the SAR images determine the best window size and the pixels in the intensity image are filtered using their own optimal windows. The proposed method is presented for both single- and multi-polarized SAR images, and the results of several common filters that were modified are presented. This approach is applied to two RADARSAT-2 images: one over San Francisco, California, USA and the other over St. John’s, Newfoundland and Labrador, Canada, producing results that were similar to, or outperformed, comparable filters while retaining details and suppressing speckle effectively. While the method was successful for single-look intensity data, it offers great potential for multi-look and amplitude data as well. 相似文献
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提出了一种基于MPM(maximization of the posterior marginals)准则的SAR图像无监督分割方法，并给出了对模拟和真实SAR图像的分割结果。 相似文献
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《Geoscience and Remote Sensing Letters, IEEE》2008,5(4):583-587