共查询到20条相似文献,搜索用时 15 毫秒
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We propose a new adaptive noise reduction method for interferometric synthetic aperture radar (InSAR) complex-amplitude images. In the proposed method, we detect residues (singular points) in the phase image as well as their neighbors at first. Normal areas that contain no residue are used for the estimation of correct pixel values at the marked residues according to 5th order non-causal complex-valued Markov random field (CMRF) model. The process is performed block-wise with the assumption of a locally stationary condition of statistics. Using a CMRF lattice complex-valued neural-network, the error energy defined as the squared norm of distance between signal and estimated values is minimized by LMS steepest descent algorithm. Eventually, the number of residues is decreased. An application is also presented. An InSAR image around Mt. Fuji is processed by the proposed technique and then phase-unwrapped by the branch-cut method. It is found that after the application of the proposed method, a better phase unwrapped image can be obtained successfully 相似文献
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A Joint Image Coregistration, Phase Noise Suppression, and Phase Unwrapping Method Based on Subspace Projection for Multibaseline InSAR Systems 总被引:6,自引:0,他引:6
Zhenfang Li Zheng Bao Zhiyong Suo 《Geoscience and Remote Sensing, IEEE Transactions on》2007,45(3):584-591
As is well known, image coregistration, interferometric phase noise suppression, and phase unwrapping are three key processing procedures of synthetic aperture radar interferometry (InSAR). The three procedures are cascaded in the conventional processing flow of InSAR. Unlike the conventional processing flow, in this paper we propose a joint processing idea to carry out image coregistration, interferometric phase noise filtering, and phase unwrapping simultaneously based on subspace projection for multibaseline InSAR systems. The joint processing method can perform the fine coregistration of all SAR images implicitly by extracting the correlation information in the neighboring pixel sets, suppress the phase noise by utilizing the orthogonality of the signal subspace and the corresponding noise subspace, and optimally estimate the unwrapped interferometric phases (or the terrain heights) by combining the pixel coherence and the baseline diversity of a multibaseline InSAR system. Simulated results are presented to verify the effectiveness of the joint processing method 相似文献
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利用多基线数据融合提高分布式卫星InSAR系统的干涉相位精度 总被引:1,自引:0,他引:1
分布式卫星干涉合成孔径雷达(InSAR)系统可以通过提供长基线来提高测高灵敏度,但长基线会给干涉相位展开带来困难。结合分布式卫星InSAR系统可以同时提供多个稳定基线的特点,该文提出利用多基线数据融合的方法来解决长基线给干涉相位展开带来的困难。文中采用了有效的数据融合方法最大似然估计(ML)法,对多基线分布式卫星InSAR系统的干涉相位进行了估计。模拟结果表明,经过多基线数据融合的干涉相位展开精度要远远大于长基线干涉相位的直接展开精度。 相似文献
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Loffeld O. Nies H. Knedlik S. Yu Wang 《Geoscience and Remote Sensing, IEEE Transactions on》2008,46(1):47-58
This paper considers the problem of unwrapping the phase image obtained from a noisy interferometric synthetic aperture radar (InSAR) image. The implicit nonlinearity of the problem is reflected, as well as the drawbacks of this nonlinearity on the performance of phase unwrapping approaches. Some general concepts concerning basic estimation techniques are shortly reviewed. On this background, a Kalman filter-based data fusion approach to unwrap and simultaneously filter the phases of InSAR images is developed. The data fusion concept exploits phase information extracted from the complex interferogram rather than from the phase image and fuses that information with phase slope information extracted from the power spectral density of the interferogram. 相似文献
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城市建筑区域叠掩、阴影严重,图像理解困难且干涉相位变化复杂紊乱,一直是InSAR处理的困难区域。SAR图像仿真能为图像理解和处理方法研究提供数据支撑,然而现有建筑区域SAR图像仿真方法大多无法获得具有相干性的干涉SAR图像对。该文提出了一种面向建筑区域的干涉SAR复图像对仿真方法,能够获得建筑的复数图像对、干涉相位图以及叠掩成分数目等信息,为城区干涉SAR处理及信息提取研究提供仿真数据支撑。同时,基于仿真中对相位变化规律的分析,提出叠掩区相位解缠时的基准确定方法,解决传统解缠方法面临的叠掩区域干涉相位不连续问题,进而反演建筑高程信息。最后,通过建模仿真结果与实际SAR图像和干涉相位的对比,验证了仿真方法的正确性,并对仿真及实际干涉相位进行解缠和高程反演处理,验证了该文高程反演方法的有效性。 相似文献
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StereoSAR与InSAR是两种利用合成孔径雷达图像重建DEM的关键技术。InSAR利用SAR干涉像对的相位信息重建高程,具有DEM重建精度高的特点,但DEM重建精度受环境、时间等失相干因素影响较大;StereoSAR是利用SAR立体像对的幅度信息重建高程,尽管DEM重建理论精度比InSAR差,但受失相干因素影响小,并且可以在缺乏外部辅助高程信息时获取绝对DEM。在传统的InSAR处理中,干涉条纹密集区域相位解缠难度较大,存在相位解缠错误和错误传播现象,且在没有地面控制点或外部DEM的时难以获得绝对DEM。文中提出了一种迭代式的基于StereoSAR辅助的InSAR高精度DEM重建方法,该方法可以在缺乏外部高程信息时获得绝对DEM,降低干涉条纹密集区域相位解缠的难度,提高DEM重建精度。采用文中所提方法、传统InSAR方法及公开DEM辅助InSAR DEM重建方法,分别在地形复杂与平坦区域进行DEM重建,并用ICESat/GLAS及TanDEM-X DEM进行精度评估。DEM重建结果验证了文中所提方法的有效性,所提方法的DEM重建精度优于传统InSAR方法且与公开DEM辅助InSAR DEM重建方法精度相当。 相似文献
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由新质量图引导的InSAR快速解缠方法 总被引:2,自引:0,他引:2
相位解缠是SAR干涉测量数据处理中的一个关键步骤之一,解缠结果的好坏直接影响最终数字高程模型的精度。该文介绍了一种新的质量图求取方法。该方法考虑到条纹宽度对传统的灰度方差质量图的影响,提出利用平面拟合来消除坡度效应后再求取灰度方差作为质量,取得良好的效果。该文还对质量图的解缠算法进行了改进,利用查找表来降低路径搜索的计算量,大大减少了解缠所需要的时间。由于InSAR图像的数据量往往很大,解缠时间的大大缩短对于这样大量数据的处理是非常有利的。对真实InSAR干涉纹图的处理结果表明,该解缠方法高效而实用。 相似文献
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合成孔径雷达干涉测量中的相位展开 总被引:1,自引:0,他引:1
合成孔径雷达干涉测量技术 (InSAR)是以合成孔径雷达复数据提取的相位信息作为信息源来获取地表的三维信息和变化信息的一项技术。相位展开是InSAR数据处理中的关键步骤之一。本文介绍了合成孔径雷达干涉测量的原理 ,重点讨论了InSAR中的相位展开算法 ,特别对与路径有关的算法和与路径无关的算法进行了分析 ,比较了各类方法的优缺点。指出一些在结构照明型计量中有效的相位展开算法也可以用于合成孔径雷达干涉测量之中的相位展开 相似文献
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SAR interferograms are affected by a strong noise component which often prevents correct phase unwrapping and always impairs the phase reconstruction accuracy. To obtain satisfactory performance, most filtering techniques exploit prior information by means of ad hoc, empirical strategies. In this paper, we recast phase filtering as a Bayesian estimation problem in which the image prior is modeled as a suitable Markov random field, and the filtered phase field is the configuration with maximum a posteriori probability. Assuming the image to be residue free and generally smooth, a two-component MRF model is adopted, where the first component penalizes residues, while the second one penalizes discontinuities. Constrained aimulated annealing is then used to find the optimal solution. The experimental analysis shows that, by gradually adjusting the MRF parameters, the algorithm filters out most of the high-frequency noise and, in the limit, eliminates all residues, allowing for a trivial phase unwrapping. Given a limited processing time, the algorithm is still able to eliminate most residues, paving the way for the successful use of any subsequent phase unwrapping technique. 相似文献
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提出了一种基于差频测角定位、等效去平地相位和模糊数估计相结合的相位解缠方法.根据波束指向信息在差频下干涉测角,对目标进行粗定位;然后借鉴干涉合成孔径雷达(InSAR)中的去平地相位技术,实现等效去平地相位,缓解相位解缠压力;最后对模糊数进行统计估计,完成相位解缠.实际数据处理结果表明,该方法不仅解决了目标尺寸较大引起的相对相位缠绕问题,而且可以获得目标的绝对相位,实现了对运动目标的三维定位与三维成像. 相似文献
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Carballo G.F. Fieguth P.W. 《Geoscience and Remote Sensing, IEEE Transactions on》2002,40(8):1695-1708
The well-studied interferometric synthetic aperture radar (InSAR) problem for digital elevation map generation involves the derivation of topography from the radar phase. The topography is a function of the full phase, whereas the measured phase is known modulo 2/spl pi/, necessitating the process of recovering full phase values via phase unwrapping. This mathematical process becomes difficult through the presence of noise and phase discontinuities. This paper is motivated by research which models phase unwrapping as a network-flow minimization problem. A major limitation is that often a substantial computational effort is required to find solutions. Commonly, these phase images are huge (/spl Gt/10 million pixels), and obviously the sheer size of the problem itself makes phase unwrapping challenging. This paper addresses the development of a computationally efficient hierarchical algorithm, based on a "divide-and-conquer" approach. We have shown that the phase-unwrapping problem can first be partitioned into independent phase-unwrapping subproblems, which can further be recombined to produce the unwrapped phase. Interestingly, the recombination step itself can be interpreted as an unwrapping problem, for which a modified network-flow solution applies! In short, this paper develops a parallelization of the network-flow algorithm, allowing images of virtually unlimited size to be unwrapped and leading to dramatic decreases in the algorithm execution time. 相似文献
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2-D phase unwrapping is an important technique in many applications. However, with the growth of image scale, how to tile and splice the image effectively has become a new challenge. In this paper, the phase unwrapping problem is abstracted as solving a large-scale system of inconsistent linear equations. With the difficulties of large-scale phase unwrapping analyzed, L(0)-norm criterion is found to have potentials in efficient image tiling and splicing. Making use of the clustering characteristic of residue distribution, a tiling strategy is proposed for L(0)-norm criterion. Unfortunately, L(0)-norm is an NP-hard problem, which is very difficult to find an exact solution in a polynomial time. In order to effectively solve this problem, equations corresponding to branch cuts of L(0)-norm in the inconsistent equation system mentioned earlier are considered as outliers, and then an outlier-detection-based phase unwrapping method is proposed. Through this method, a highly accurate approximate solution to this NP-hard problem is achieved. A set of experimental results shows that the proposed approach can avoid the inconsistency between local and global phase unwrapping solutions caused by image tiling. 相似文献