ENVISAT ScanSAR干涉数据处理研究

ScanSAR干涉测量是一种三维测高模式,而且ScanSAR模式也是SAR卫星的一种工作模式,且具有宽覆盖、大范围和重返周期短的优点。本文结合ScanSAR的工作原理及特点,分析了ScanSAR的成像算法,针对ScanSAR的数据处理的关键点,提出了采用分字条带处理的方法来剔除轨道误差,消弱拼接、大地水准面差距、大气效应的误差。在此基础上,使用GAMMA软件给出处理流程,然后通过对ENVISAT卫星的青藏高原宽幅数据的处理,进行实验对比,证明该方法的有效性,并为ScanSAR干涉测量的进一步研究提供了重要的科学参考。     

ScanSAR干涉测量中的关键误差影响

ScanSAR模式具有宽观测带和重访时间短的优点,广泛应用于地表形变监测,在监测缓慢形变领域具有宽广的前景。ScanSAR干涉测量与条带干涉一样,降低基线误差和DEM残差影响是其主要瓶颈。本文分析了ScanSAR的成像原理及误差成因,针对Bam地震的ScanSAR干涉图,比较了SRTM3和GDEM在ScanSAR差分干涉中的影响大小,对采用3种不同精度的ENVISAT轨道数据得到的ScanSAR干涉结果进行了比较研究,研究结果可为相关领域提供参考。     

星载方位多波束ScanSAR 成像

提出了一种新型星载方位多波束ScanSAR 工作模式, 实现了在保持方位向高分辨率的前提下对距离向 测绘带大幅扩展。分析了该工作方式的特点及主要相位误差, 给出了相应的误差补偿方法。介绍了该工作方式下回 波数据的模拟方法, 并讨论了几种适合该工作方式的成像算法。最后通过仿真对该工作方式的可行性及补偿方法的 有效性进行了验证。     

星载宽幅SAR干涉测量研究

星载宽幅SAR也称为ScanSAR,其干涉测量是一种宽测绘带的三维测高和变形监测模式。本文介绍了ScanSAR模式(Wide Swath Mode,WSM模式)干涉测量及其与IM模式(Image Mode)联合干涉测量的方法,提出ScanSAR干涉数据处理的具体实现方案,并通过实例验证了ScanSAR干涉测量不仅能得到与IM模式同样的监测结果,而且其覆盖面较广,易发现大范围的变形,尤其是大区域的缓慢形变。     

ScanSAR模式海冰图像的分割

合成孔径雷达SAR(Synthetic Aperture Radar)图像的非平稳性是SAR海冰图像自动解释的主要障碍,入射角效应是导致海冰图像特征不稳定的主要因素之一。基于Radarsat-1 ScanSAR模式数据,本文提出了一种集成入射角效应校正步骤的分割算法。该方法综合考虑了入射角效应、斑点噪声等不确定因素,经由像素到区域再到大尺度区域这一途径,把区域聚类、类尺度上的入射角效应校正以及区域合并等操作组合起来,以有效提高分割算法对非平稳性的适应能力。针对巴芬湾和和波斯尼亚湾ScanSAR模式图像的实验表明,本文提出的方法可有效提高分割准确性。     

星载宽幅SAR干涉数据处理研究

结合ScanSAR的工作原理和特点,提出了分条带处理的方法,分析了ScanSAR数据处理的关键,对比分析叠片式条带拼接和配准加权拼接两种方法,提出了改进的配准加权方法,并用实验证明了本文提出的分条带处理方法和改进的配准加权方法的可行性和可靠性,为ScanSAR干涉测量的进一步研究提供了科学参考。     

基于小波多分辨率分析方法的海冰遥感影像数据融合

采用小波多分辨率分析方法，对辽东湾2000－01－18的海冰遥感数据（NOAA／ARHRR和Radarsat/ScanSAR)进行了融合分析，并从几方面对结果作了深入的分析和对比。文中首次采用了小波分析中的多层次分解和重构技术用于数据融合分析。     

异构环境下的多子阵合成孔径声呐精确后向投影快速成像方法

针对多子阵合成孔径声呐精确后向投影成像算法效率低的问题,提出了 一种异构环境下的精确多子阵合成孔径声呐后向投影成像快速方法.在分析精确逐点后向投影成像算法原理的基础上,将脉冲压缩和方位向聚焦过程改造为单指令多线程模式,借助图形处理器(graphics processor unit,GPU)强大的多核计算能力加速成像过程...     

星载ScanSAR成像研究

分析扫描模式合成孔径雷达不同于传统合成孔径雷达回波的时，频域特点。通过对不同成像方法及加拿大RadarSAT扫描模式雷达实际回波数据的理解，根据扫描模式雷达回波的特点，实现了全孔径RD算法，快速SPECAN算法和Chirp Scaling算法几种适合于扫描模式雷达波成像的算法，并在算法实现过程中结合实际数据讨论了抑制点目标回波旁瓣，实现快速距离走动校正，减弱Scalloping效应，抑制方位向重影，准确估计多普勒中心频率等问题，针对这些问题提出了一些新方法并通过模拟或实际数据成像进行了验证。     

SAR 图像中不同特性条纹噪声的滤除

分析Burst工作模式星载SAR 系统中, 采用全孔径成像算法会产生周期性明暗条纹噪声的原因, 提出一种简单高效的一维频域滤除算法, 并给出包含该操作的改进距离多普勒成像算法流程。对于因雷达系统本身原因而产生的一些非周期不规则条纹噪声进行讨论, 针对此类噪声提出一种二维频域区域滤波的算法。通过对实际星载SAR 数据的处理, 验证算法的有效性。     

星载宽幅雷达干涉监测大范围地震形变技术研究

宽幅雷达成像模式可监测大范围地震形变,但该模式与条带成像模式存在差异。针对这些差异,深入分析了图像拼接、大气效应校正和大地水准面差距改正等方面的关键技术,提出了基于配准加权的拼接方法和基于EGM96的大地水准面差距改正方法,分析了适应于宽幅SAR干涉的大气校正模型。在此基础上,对ENVISAT卫星宽幅数据干涉测量成果进行了校正,并分析了汶川地震和于田地震的宽域形变场。     

Interferometry with ENVISAT wide swath ScanSAR data

The possibility to get efficient topographic mapping and monitoring of large-scale motions with ScanSAR interferometry has been demonstrated with the Shuttle Radar Topography Mission and RADARSAT mission. The Environmental Satellite Advanced Synthetic Aperture Radar (ASAR) sensor has been designed to provide enhanced capabilities for interferometric applications. Different types of interferometric products can be obtained by combining the various ASAR modes as stripmap synthetic aperture radar [image mode (IM)] and ScanSAR [wide swath (WS) mode]. This letter deals with the possibility to use WS data to get either mixed-mode (IM/WS) or ScanSAR mode (WS/WS) differential interferograms. The impact of digital elevation model localization errors on IM/WS interferograms and of scan pattern synchronization on WS/WS interferograms is investigated. Experimental results are encouraging and show that ASAR ScanSAR data can be routinely used for interferometric applications in both cases.     

Automatic Detection of Oil Spill Disasters Along Gulf of Mexico Using RADARSAT-2 SAR Data

In this work, the genetic algorithm is utilised for automatic detection of oil spills under wind speed conditions larger than 20 ms^?1. The procedure is implemented using sequences of RADARSAT-2 SAR ScanSAR Narrow single beam data acquired in the Gulf of Mexico. The study demonstrates that implementing crossover allows for generation of accurate oil spills pattern. This conclusion is confirmed by the receiver–operating characteristic (ROC) curve. The ROC curve indicates that the existence of oil slick footprints can be identified with the area under the ROC curve and the no-discrimination line of 85 %, which is greater than that of other surrounding environmental features. In conclusion, the genetic algorithm can be used as a tool for the automatic detection of oil spills and the ScanSAR Narrow single beam mode serves as an excellent sensor for oil spill detection and surveying under wind speed larger than 20 ms^?1.     

Open water detection from Baltic Sea ice Radarsat-1 SAR imagery

An algorithm for open water and sea ice discrimination for Radarsat-1 ScanSAR images is presented. The algorithm is based on segmentation and local synthetic aperture radar signal intensity autocorrelation. The algorithm performance is evaluated by comparing the results to operational digitized ice charts, in which the sea ice information is based on human interpretation of multiple data sources, including remote sensing data. The algorithm locates the open water of the digitized ice charts with about 90% accuracy.     

Narrow-Band Interference Suppression for SAR Based on Complex Empirical Mode Decomposition

Narrow-band interference (NBI) is a common interference source in synthetic aperture radar (SAR) imaging. Its existence will degrade the imaging quality greatly. Based on detailed analysis on the characteristics of NBI, this letter proposes a new NBI suppression algorithm using the complex empirical mode decomposition (CEMD) method. In this algorithm, echoes that include NBI are recognized in the time domain first. Then, these echoes are decomposed into a number of intrinsic mode functions (IMFs) via the CEMD. After that, IMFs that correspond to NBI are subtracted from the echoes by thresholding. Finally, well-focused SAR imagery can be obtained from the separated target echoes using traditional SAR imaging algorithms. The effective data loss in this algorithm is smaller than other NBI suppression approaches. In addition, this algorithm is robust to time-varying NBI. Imaging results of measured data have proved the validity of this algorithm.