一种最短分割路径的相位解缠算法

用中国广东地区的DEM数据和ENVISAT-ASAR参数,按SAR成像机理和双尺度粗糙面散射计算构造SLC数据,通过按比例变更DEM的起伏程度造成具有不同的起伏高度和阴影,进而构造了多景不同残差点数量的相干数据。该数据能够有效的估评检验各种InSAR解缠算法,有助于分析实际图像阴影对InSAR反演DEM误差的影响。在路径跟踪的解缠算法中,路径越短解缠效果越好。提出了一种路径跟踪的相位解缠算法,其利用蚁群算法求解连接残差点的最短路径,然后对该路径进行了分割,生成连接相邻异性的残差点对的分割路径,能够在解缠过程中避免出现“解缠孤岛”现象。将该算法分别应用于多景仿真SLC数据的相干图像和ENVISAT-ASAR伊朗Bam地区的InSAR图像,并与其它几种解缠算法作了比较。数据实验结果表明:该算法可有效的应用于各种复杂地形的InSAR图像的相位解缠,与其它解缠方法相比,具有一定的优越性。     

残差点退化的统计费用网络流机载相位解缠算法

目的 相位解缠是InSAR干涉数据处理的关键步骤,而解缠不连续（即相位跳变）问题却普遍存在,尤其在机载InSAR系统中,由于数据的高分辨率,使得低矮地物如树木带在数据中表现为相位不一致,因而相位跳变问题更加显著。星载InSAR相位解缠广泛使用统计费用网络流（SNAPHU）算法^[1],借鉴其经验将SNAPHU算法引入高分辨机载InSAR相位解缠。而残差点退化方法能有效补偿局部相位不一致区域。因此本文提出一种结合残差点退化方法与SNAPHU算法的高分辨率机载InSAR相位解缠算法。方法 将原始InSAR数据滤波且去除平地相位,再对其进行残差点退化处理。残差点退化包含残差点定位,及残差点补偿两部分。根据残差点及其邻域像元的性质,对残差点进行补偿使其退化为非残差点,不断迭代这一过程,以减少图像中的残差点,优化局部数据。根据机载InSAR系统定标参数,修正SNAPHU算法中的参数及几何模型,使用修正后算法进行相位解缠。结果 利用2011年四川江油地区的单轨双天线X波段机载InSAR数据进行了试验,试验结果表明,在相位不一致,相干性低的连续树木带区域,该算法显著缩小了解缠相位不连续区域,修正了大面积的相位跳变。结论 验证了残差点退化方法结合统计费用网络流算法可有效解决解缠相位大面积跳变问题,且对噪声具有鲁棒性。     

基于机载InSAR生成DEM技术研究试验

本文描述了机载双天线合成孔径雷达干涉测量数据生成数字高程模型(Digital Elevation Model,DEM)技术,针对机载双天线InSAR数据自动生成DEM的数据处理流程进行试验,主要包括:复图像配准、干涉条纹图滤波、相位解缠、相高转换。本文基于VC++开发了机载InSAR干涉处理原型系统,利用分辨率为2m×2m的机载双天线X波段InSAR数据进行了干涉处理实验,并将生成的DEM和实测的控制点数据进行了对比分析。试验结果证明基于机载双天线InSAR数据生成DEM技术可满足1:50000的精度要求。     

多基线InSAR技术的震区DEM提取及精度分析

针对汶川特大地震发生后的震区地形严重破坏，原有的地形图及DEM数据不再具有时效性，不能准确地描述地质特征，亟待更新重建。收集了2007年8月至2010年7月的20景Envisat ASAR影像数据，采用多基线InSAR技术对研究区域DEM进行提取，并对生成的ASAR DEM与ASTER GDEM和SRTM DEM进行了比较分析。实验结果表明，由于时效性原因，ASTER GDEM和SRTM DEM不能较好反映震后地面高程变化情况；所提取的ASAR DEM能有效弥补震后灾区DEM不足，在一些植被较少和地质稳定区域，ASAR DEM有着较高的精度，多基线InSAR技术提取方法为震后形变区域DEM提取提供了一个很好的途径。     

基于改进混合像元方法的MODIS影像水体提取研究

基于MODIS的反射率数据,利用改进的线性混合像元分解方法提取水体,并结合MODIS温度产品和SRTM的DEM数据校正阴影对提取结果的影响。通过和利用ETM+影像的水体提取结果对比分析得出:该方法结果较好的体现出河流和湖泊的细节特点,同时在很大程度上消除了阴影影响,面积提取结果具有较高的精度。     

结合影像和LiDAR点云数据的水体轮廓线提取方法

从遥感影像中提取水体的传统方法在阴影处和水体浑浊处存在一定局限;机载激光雷达（LiDAR）获取点云数据时水体受阴影和浑浊的影响小,因此使用点云数据提取水体比使用影像数据更加稳健;但点云数据的分辨率低,所提取的轮廓线精度不高。为了提高水体边缘轮廓线的精确度,提出一种高分辨率影像与点云数据相结合的水体轮廓线提取方法。实验结果表明,该方法所提取的水体轮廓线定位精确、细节完好,水体提取准确率达到98.6%。     

利用卫星激光测高数据对星载SAR干涉测量DEM进行倾斜改正的研究

InSAR与ICEsat测高技术作为极具潜力的两项对地观测技术,各有其特点,利用卫星激光测高数据对星载SAR干涉测量DEM进行倾斜改正具有十分重要的意义,为提取无控制特殊困难地区大范围DEM提供了一种全新的方法。本文介绍了InSAR与ICEsat激光测高两种技术的特点及互补性;分析了利用ICEsat测高数据改正InSAR数据本身难以消除的误差的可行性;并以南极Grove山大范围DEM的提取为例,证实了其优越性。     

ENVI SARscape高级雷达数据处理工具

合成孔径雷达（SAR）拥有独特的技术魅力和优势,逐渐成为国际上的研究热点之一,其应用领域越来越广泛。SAR数据可以全天候对研究区域进行量测、分析以及获取目标信息。InSAR技术可提取地形信息和地表形变信息,SAR及其干涉测量技术主要应用于地形数据（DEM）提取、地表沉降监测、滑坡／冰川移动监测、目标识别与跟踪、原油泄漏...     

InSAR技术获取高山峡谷区DEM精度研究

通过对金沙江河段高山峡谷区L波段的Alos-Palasar和C波段的Radarsat-2雷达单视复数数据的干涉处理,获取此区域的数字高程模型(DEM)。利用SRTM 90m分辨率的DEM为参考数据,通过对比分析发现InSAR技术生成的DEM精度与相干系数、地形和波长有密切的关系。同时也验证了在相干性好,地形起伏不太剧烈的地区,用InSAR技术生成DEM是可行的。     

基于机载LiDAR 技术的典型水库水量变化估算

针对传统外业测量水库库容估算方法易受地形、气象条件影响,存在危险性高、效率低等问题,以仑山水库为研究对象,采用机载 LiDAR 技术估算水库面积及水量变化。通过实地数据采集,利用 KD- 树算法剔除点云中的粗差点,并采用渐进加密不规则三角网(PTIND)滤波分离出地面点,完成 LiDAR 点云数据的预处理;根据点云数据建立精细化数字高程模型(DEM),提取不同水位的水库水面面积;最终利用积分和传统棱台体积估算方法对比分析不同水位水量差值变化。结果表明：与高程实测值相比,DEM 高程反演值满足高程精度要求,基于机载 LiDAR 的水量估算受库底坡度变化的影响,估算值低于传统估算方法的估算值,估算结果更为精确,可为监测水库水量变化提供科学依据。     

一种基于干涉成像几何的水体类地表干涉处理方法

干涉合成孔径雷达在地形高程测绘方面有其独特的优点。工程应用中,场景中的水体类地表由于后向散射系数极小,相干性差,导致相位信息的噪声大,最终严重影响反演DEM的质量,以及由此得到的雷达正射影像的质量。提出了一种基于干涉成像几何的水体类地表在相位域进行干涉处理的方法,恢复场景中水体区真实相位,以得到高质量的DEM。通过对实测的机载干涉SAR数据进行处理,取得了很好的效果,验证了算法的有效性。     

Joint interferometric calibration based on block adjustment for an airborne dual-antenna InSAR system

Mapping large areas using airborne dual-antenna interferometric synthetic aperture radar (InSAR) usually requires processing and mosaicking of different scenes from multiple strips. The overlapping areas of these multiple strips should have consistent elevation values. Due to the unstable attitude of the plane, the interferometric parameters usually vary for each scene during mapping. Therefore, interferometric calibration technology for high-precision height retrieval is required for the correction of the interferometric errors. The traditional interferometric calibration methods for a single scene usually use ground control points (GCPs) to estimate the interferometric parameters – this method cannot guarantee a consistent height in the area of overlap. Besides, GCPs are difficult to deploy over rough terrain, making it impossible to use traditional calibration methods. In this article, a joint interferometric calibration method based on the block adjustment theory used in photogrammetry is proposed for airborne dual-antenna InSAR. This method considers the accurate digital elevation model (DEM) height reconstruction model and can be applied with sparse GCPs. The principle of the proposed method is to make the best use of the GCPs within all the scenes and the tie points (TPs) between the adjacent scenes to establish an error relationship model. First, the weighting values of all GCPs and TPs based on their retrieval elevation error caused by the interferometric phase error and the position distribution difference are introduced in the proposed method. Next, the interferometric parameters are weighted to reduce the condition number of the normal equation. Then, an alternative approximation approach combined with the sparse matrix decomposition technique LDL^T is utilized to solve the normal equation, and the corrected interferometric parameters for each scene are obtained. High-precision joint interferometric calibration results for airborne InSAR systems are achieved by the proposed method and validated by experiment. Using the proposed method, the average mean error (AME) and root mean square error (RMSE) are below 0.6037 and 0.9176 m, respectively. Meanwhile, the maximum AME and RMSE of the reconstructed DEM height difference for the validation TPs in the overlapped area of the adjacent scenes are reduced from 1.2909 and 1.7245 m to 0.8864 and 1.2087 m, respectively.     

应用Kriging插值方法插补干涉雷达DEM奇异值斑块

干涉合成孔径雷达（InSAR)可以获取地表的三维信息，但是由于雷达数据的热噪声等原因，使得干涉雷达获取的DEM存在高程奇异值斑块，严重影响了InSAR获取DEM的应用。鉴于高程奇异值斑块的DEM中分布的随机性，以及一般DEM数据具有的空间连续性和空间自相关性，针对这一问题，笔提出了利用基于空间统计学的Kriging插值法插补DEM的高程奇异值斑块。本对STRM提供的DEM进行了插补，同时对插补的结果进行了精度分析。结果表明可以满足DEM的应用精度要求。     

DEM generation and error analysis using the first Chinese airborne dual-antenna interferometric SAR data

Terrain survey with traditional photogrammetry is often difficult in western China, such as Qingzang tableland at an average height of 5000 m above sea level and the southwest China area with cloudy weather. To resolve western terrain mapping, the first Chinese single-pass airborne Interferometric Synthetic Aperture Radar (InSAR) system was successfully developed by the Institute of Electronics, Chinese Academy of Sciences (IECAS) in 2004. The main objective of this article is to examine and evaluate the performance of the airborne SAR system through interferometric processing and error analysis. First, the article describes how high-precision digital elevation models (DEMs) are derived from the airborne dual-antenna (single-pass) InSAR data. In order to improve the precision, the antenna eccentricity correction and parameter calibration with the least square method (LSM) are proposed. Based on the airborne dual-antenna InSAR bore-sight model, this article summarizes the primary factors that influence the accuracy of DEMs in data processing, and analyses the errors induced by these factors. Then, the global positioning system (GPS)/inertial measurement unit (IMU) data, acquired and stored by the position and orientation system (POS), is used for analysing the quantitative relationships among the platform height, baseline length, baseline angle, look angle and DEM error. The experimental data used are airborne dual-antenna X-band InSAR data, and the measured ground control points (GCPs) are used to validate the accuracy of the DEM. The evaluation results in terms of the standard deviation (SD) and the average mean error (AME) are derived by comparing the reconstructed InSAR DEM with the reference GCPs. The AMEs of the X-direction, the Y-direction and the height are up to 2.078, 9.149 and 1.763 m, respectively. The SDs of the X-direction, the Y-direction and the height are up to ±1.379, ±0.764 and ±1.086 m, respectively. These results agree with the previously calculated quantitative errors. The error value of the Y-direction seems too large, a possible result of system errors. In general, the airborne dual-antenna InSAR system initially meets the requirements of 1:50 000 terrain mapping in western China.     

基于区域网平差的干涉合成孔径雷达数字高程模型校正

合成孔径雷达干涉测量（InSAR）是获取数字高程模型（DEM）的常规手段,而通过干涉技术获得DEM后,其精度会受到轨道定位、影像的配准、干涉图获取、相位解缠等精度的影响。已有的利用区域网平差提升DEM精度的研究忽略了DEM的初始平面定位误差的影响。引入DEM的平面高程一体化区域网平差,将区域网平差分解为平面定位六参数的优化和高程误差模型的平差求解两个独立的平差过程,同时利用激光测高数据作为高程控制。从哨兵干涉生成的20 m分辨率DEM实验结果看,平差后DEM的高程均方根误差（RMSE）从平差前的19.372 m提升到了3.459 m。DEM对应连接点的平面内符合精度RMSE从初始182.462 m提升至14.887 m。而传统的不考虑平面误差的DEM优化方法在平差后高程精度提升至7.865 m,远低于所提出的方法,验证了提出的考虑平面误差的区域网平差方法的有效性。     

Construction of a high-resolution DEM of an Arctic ice cap using shape-from-shading

Digital elevation models (DEMs) of ice sheets and ice caps are usually constructed from elevation data acquired from airborne or satellite-borne altimetric systems. Consequently, the DEMs have a spatial resolution of about 1km which limits their use for most glaciological and remote sensing studies. In this paper we investigated the possibility of using a shape-from-shading technique, applied to a Landsat MSS image, to create a high spatial resolution DEM of Austfonna, an ice cap in Svalbard. A high correlation (coefficient of determination = 0.85) was observed between Landsat pixel brightness values, acquired during winter, and the surface slope component parallel to the solar azimuth. This relationship was used to create a DEM by calculating surface elevation profiles across the ice cap, using low spatial resolution radio echo sounding data as tie points. The resulting DEM had an estimated rms error of about 14m, with the error occurring mostly at low spatial frequencies. Shape-from-shading produces less accurate DEMs than interferometric SAR (InSAR) techniques. Nevertheless, in scenarios for which InSAR cannot be used to construct a DEM, shape-from-shading provides an acceptable alternative.     

星载SAR干涉技术获取DEM及其精度分析

星载合成孔径雷达干涉（InSAR）技术是一种数据覆盖范围广、廉价、高效、方便的数字高程模型（DEM）获取方法,但在地面植被覆盖广、大气水汽含量高的地区其影像相干性随时间基线的增加迅速降低;同时,SAR卫星的轨道误差也影响DEM精度。利用ERS-1/2卫星串行模式SAR数据获取镇江地区DEM,分析了轨道误差对DEM精度的影响;根据干涉相位的统计特性,从理论上给出干涉相位噪声与相干系数和视数之间的关系。实验结果表明就干涉像对的卫星轨道误差和相位噪声而言,在小区域内DEM精度优于3.5 m。     

Development of Forest Height Estimation Using InSAR/PolInSAR Technology

Forest height estimation is one of the hottest research areas of InSAR/PolInSAR technology within its 30 years’ development.Estimation algorithms play an important role in the forest height assessment by InSAR/PolInSAR technologies.This paper systematically reviewed the basic theories,model assumptions and then summarized the limitation and potential of these algorithms applied in forest height estimation,especially performed in regional or global scale.It also deliberated the intrinsic characteristics of these algorithms like DEM difference method,three\|stage inversion process,coherence amplitude method and so on.Analysis showed that the estimation results of DEM difference method had higher accuracy and less influence from forest types and structure.So it had great potential for global and regional forest height assessment,however,it was limited by the requirement of high accuracy DEM data in those area.The result accuracy of algorithms based on PolInSAR depended more on forest types,structures and also the robust of forest scattering models.It had no restriction of DEM and could perform in global and regional scale,but for the forest area with great heterogeneous,model and algorithm suitability and robust need to further studying.Besides,for the poor penetration of single\|baseline InSAR/PolInSAR,we should focus more on multi\|dimension,multi\|baseline technique for InSAR/PolInSAR application development in the future.     

基于正侧视模型的机载双天线干涉SAR外定标方法

采用基于敏感度方程的方法,研究了基于正侧视成像模型下的机载双天线干涉SAR系统的外定标问题。算法通过对干涉成像方程各参数求导,得到基于敏感度方程的误差模型,并在此基础上,依据若干地面控制点的精确数据,求解干涉参数偏差。通过迭代求解,得到定标后的干涉参数,并生成精确的数字高程模型及对地面目标点进行定位。利用我国自主设计、研制的机载干涉SAR系统获得的数据,进行了外定标处理实验,验证了方法的有效性。     

机载X-波段双天线InSAR数据森林树高估测方法

短波长的干涉合成孔径雷达(InSAR)适用于数字表面模型(DSM)提取,但难以提取准确的林下地相位,在缺乏高精度数字高程模型(DEM)的森林区域,短波长InSAR数据估测树高的能力受到限制。针对这一问题,采用机载X-波段单极化(HH)双天线InSAR数据开展了森林树高估测方法研究。双天线InSAR可以忽略时间去相干的影响,并且X-波段波长较短,入射角较大(中心入射角45.77°),地表对干涉去相干的贡献可以忽略,因此可将干涉复相干作为体去相干,对体去相干模型中的结构函数进行勒让德展开,截取第0阶展开式得到了基于相干幅度的森林树高估测模型,利用均匀选取的LiDAR冠层高度模型(CHM)检验样本对估测结果进行严格的精度评价,并与差分法的树高估测结果进行对比。精度评价结果显示:相干幅度法与差分法都得到了较高的估测精度,两者的R~2、RMSE、总精度分别为0.81、0.86;1.20m、0.97m;86.4%、88.7%。研究结果表明:相干幅度与森林树高具有负相关关系,适用于估测树高,基于单极化相干幅度的估测模型也可以得到较高的估测精度,与差分法的估测结果相比,虽然估测精度略有降低,但此方法具有两方面的优势:一方面,估测结果不需要实测样地数据标定,对于没有实测样地数据的森林区域亦能进行高精度的树高估测;另一方面,相干幅度法不需要高精度的DEM,具有更强的实用性。