Capability of mapping surface deformation offered by satellite radar interferometry has been successfully demonstrated and applied since early 90s, from short to long terms measuring and tracing of deformation pattern...Capability of mapping surface deformation offered by satellite radar interferometry has been successfully demonstrated and applied since early 90s, from short to long terms measuring and tracing of deformation patterns up to centimeter scale, both qualitatively and quantitatively. There remain limits in mapping earthquake triggered deformations in temporal and spatial scales, however, as already indicated in case of Chi-Chi Earthquake. This report focuses on the analysis of pre-and post-seismic deformation patterns derived from series of ALOS-PALSAR data. A novel InSAR processing flow was applied. First, an automatic registration method starts with the estimation of initial offset between slave and master images, selection of tie points, and followed by a refined matching by means of spatial feature analysis and pyramidal matching. A newly developed noise filter was then applied to the interferograms before phase unwrapping. To ensure the accuracy and robustness of the processing chain, results between InSAR derived and those from leveling measurements over a test site in Taiwan was compared and found to be very satisfactory. Deformation pattern mapped by ALOS/PALSAR differential interferometry with Fine Beam Single(FBS) and Fine Beam Daul(FBD) data pairs along the Longmenshan fault zone(LMSFZ) about 400 km from Wenchuan to Beichuan, Sichuan. The co-seismic interferogram was generated with 42 scenes(FBS, 3frames/track, total 7 tracks from Pass 470 to Pass 476, since 20 Jul., 2007 to 7 Feb., 2009), while the pre-seismic and post-seismic PALSAR interferogram with 21 scenes(Pass 475, both FBS and FBD, since 20 Jul., 2007 to 7 Feb., 2009) on the Wenchuan epicenter area were produced. It is suggested from the preliminary analysis that the deformation did occur before earthquake and recovered elastically after the earthquake. In the future, these results should be confirmed by comparing with the ground survey and GPS observation data.展开更多
针对空空时间反转多信号分类(time reversal multiple signal classification,TR-MUSIC)抗噪性能差而难以实现对复杂随机介质影响下目标的聚焦成像,以及空空多态数据矩阵的获取较为复杂等问题,提出基于空频分解的时间反转成像新方法,即...针对空空时间反转多信号分类(time reversal multiple signal classification,TR-MUSIC)抗噪性能差而难以实现对复杂随机介质影响下目标的聚焦成像,以及空空多态数据矩阵的获取较为复杂等问题,提出基于空频分解的时间反转成像新方法,即空频TR-MUSIC。该方法利用天线阵列采集的散射场回波信号建立空频多态数据矩阵,对该矩阵进行奇异值分解得到噪声子空间向量,从而实现对目标的成像。基于完全散射场数据的成像函数包含多个子矩阵的贡献,具有统计特性。仿真结果表明,无论是在自由空间中还是在随机介质背景下,空频TR-MUSIC的成像效果均优于传统的空空TR-MUSIC,具有较好的分辨率和定位精度。即使在信噪比为10 dB的高斯白噪声影响下,也能实现对目标的准确成像。展开更多
文摘Capability of mapping surface deformation offered by satellite radar interferometry has been successfully demonstrated and applied since early 90s, from short to long terms measuring and tracing of deformation patterns up to centimeter scale, both qualitatively and quantitatively. There remain limits in mapping earthquake triggered deformations in temporal and spatial scales, however, as already indicated in case of Chi-Chi Earthquake. This report focuses on the analysis of pre-and post-seismic deformation patterns derived from series of ALOS-PALSAR data. A novel InSAR processing flow was applied. First, an automatic registration method starts with the estimation of initial offset between slave and master images, selection of tie points, and followed by a refined matching by means of spatial feature analysis and pyramidal matching. A newly developed noise filter was then applied to the interferograms before phase unwrapping. To ensure the accuracy and robustness of the processing chain, results between InSAR derived and those from leveling measurements over a test site in Taiwan was compared and found to be very satisfactory. Deformation pattern mapped by ALOS/PALSAR differential interferometry with Fine Beam Single(FBS) and Fine Beam Daul(FBD) data pairs along the Longmenshan fault zone(LMSFZ) about 400 km from Wenchuan to Beichuan, Sichuan. The co-seismic interferogram was generated with 42 scenes(FBS, 3frames/track, total 7 tracks from Pass 470 to Pass 476, since 20 Jul., 2007 to 7 Feb., 2009), while the pre-seismic and post-seismic PALSAR interferogram with 21 scenes(Pass 475, both FBS and FBD, since 20 Jul., 2007 to 7 Feb., 2009) on the Wenchuan epicenter area were produced. It is suggested from the preliminary analysis that the deformation did occur before earthquake and recovered elastically after the earthquake. In the future, these results should be confirmed by comparing with the ground survey and GPS observation data.
文摘合成孔径雷达(Synthetic Aperture Radar,SAR)作为一种主动微波传感器,被广泛应用于遥感对地观测。然而,传统上的雷达散射模型是基于几何光学近似的,忽略了地物目标之间的相互作用,即多次散射效应。为了充分挖掘和利用毫米波雷达影像中目标电磁散射特性信息,亟需对典型目标的多次散射效应进行建模仿真和验证。基于矩量法(Method of Moments,MoM)分析了球体、二面角等目标表面等效电流分布与分段成像结果的对应关系,并利用后向投影(BackProjection,BP)算法进行电磁仿真成像,总结了单/双基地雷达模式对成像中散射机制的影响。结果表明:目标表面等效电流分布以及分段等效合成孔径张角会随入射角度发生改变,其中分段等效合成孔径张角会影响方位向分辨率;双基地雷达成像结果中包含更丰富的电磁散射信息。本研究可为SAR系统设计和验证、典型目标回波特性数据收集以及如何基于高解析度SAR影像进行目标识别等研究提供借鉴与参考。
