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。     

基于外部DEM的InSAR图像配准方法研究

雷达图像的配准是进行雷达干涉测量(SAR Interferometry, InSAR)处理的关键,为了保证干涉相位图或形变相位图反映真实地面特性,需要雷达图像之间亚像元级精度的配准。首先综述了已有的基于外部DEM的InSAR图像配准方法的思路及其不足之处,并提出了一种全新的思路:以图像之间的相干性作为目标函数,利用搜索的方法实现了雷达成像方位向和距离向的最优时间常数的估计,从而实现雷达图像之间亚像元级配准;还进一步推导了数字高程模型(Digital Elevation Model, DEM)的误差对算法精度影响的一个更加严密的表示。结论表明,在利用精确轨道数据的情况下,美国航天飞机测地计划SRTM获得的地形数据的精度可以满足精确雷达图像配准的要求。结果表明,利用基于外部DEM算法配准雷达图像在山区和大的时间基线情况下要优于常规相干多项式配准方法,理论上可以达到百分之一个像素的配准精度。     

基于三维重建模型的机载双天线干涉SAR外定标方法及实现

采用三维重建模型,研究了机载双天线干涉SAR系统的外定标问题。算法采用基于敏感度方程的方法,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,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。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。     

旋翼无人机载SAR杠杆臂误差补偿算法

研究旋翼无人机作为合成孔径雷达(Synthetic Aperture Radar,SAR)的移动平台,为了提高机动灵活性,但是同样也会带来剧烈的飞行扰动.通常借助于全球定位系统(Global Positioning System,GPS)实时获取雷达位置是常用的机载SAR运动补偿方法,但是GPS天线和雷达天线的安装位置在空间上并不重合,而二者之间的空间位置差被称为杠杆臂,杠杆臂的存在使得GPS测量结果并不能真实表征雷达天线位置,直接使用GPS测量结果将使得运动补偿出现偏差.提出的杠杆臂补偿方法,能够根据GPS测量结果实时解算雷达天线位置,从而使用更为准确的雷达运动参数补偿误差,获取高精度高质量的SAR图像.从旋翼无人机运动模型入手,分析了杠杆臂误差对成像的影响,并给出了依据GPs和姿态数据演算的雷达天线位置.最后,在仿真的基础上引入了实测的旋翼无人机的运动数据,验证了改迸算法的有效性.     

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。     

机载高分辨SAR系统成像技术

基于某机载高分辨SAR系统的飞行试验,研究机载高分辨成像面临的问题以及补偿措施。由于INS/GPS数据难以满足精度要求,研究从回波数据中提取多普参数,进行运动补偿和视线位移补偿;剩余相位误差通过PGA进行补偿,从而得到0.3 m高分辨SAR图像的成像。     

高精度动态GPS在机载新型SAR上的应用研究与分析

随着机载SAR的发展,尤其是对机载干涉SAR和高分辨率SAR系统的研究深入,机载 SAR系统迫切需要精确的三维位置、速度、加速度以及姿态信息来进行机载SAR的运动测量和运动补偿处理,并需要严格的时间同步。而高精度动态GPS系统可以实时地提供精确的位置、速度和时间等信息,因此高精度动态GPS成为新型机载SAR系统的重要组成部分。对高精度动态GPS 在机载新型SAR上的应用进行了研究,并在实际机载SAR飞行应用和SAR图像处理中发挥了重要作用。     

一种EMD的SAR图像自适应辐射均衡方法

针对合成孔径雷达(synthetic aperture radar,SAR)侧视观测模式及天线方向图引起的SAR图像辐射差异严重影响SAR图像的广泛应用问题,根据经验模态分解(empirical mode decomposition,EMD)技术的自适应、自驱动和多尺度等特性,提出了基于EMD技术的SAR图像自适应辐射均衡方法。该方法利用EMD技术获取SAR图像距离向的多阶本征模函数,自适应地确定包含辐射误差的低频信息,并将其优化可获得辐射误差趋势信息和补偿因子,从而均衡SAR图像。将该方法应用到已知误差趋势的仿真数据以及多组机载SAR真实数据,结果表明该方法能够有效地自适应补偿SAR图像的辐射差异,提高了SAR图像的可视化效果和解译能力。     

干涉合成孔径雷达复图像配准解析搜索方法

图像配准是干涉SAR数据处理中关键步骤之一,它的处理精度直接影响着高程重建的质量.为了克服经典方法带来误差的影响,本文构建了一种解析代价函数,利用双迭代优化算法与弦割法求取亚像元级偏移量,实现了在连续域内搜索,避免了传统的在离散域搜索带来的误差,提高了配准精度,在插值意义上,配准精度达到最优.基于实测数据的实验结果表明,该算法具有较高精度.     

基于FFT平移与相关分析的多尺度星载SAR自动配准

SAR图像配准是SAR图像应用,尤其是时间序列SAR图像应用的重要处理步骤之一。为实现重复星载SAR图像的快速、自动配准,通过将小波多尺度变换与快速傅立叶频谱变换相结合,实现了对星载SAR图像间初始偏移的快速估计,并在此基础上利用基于窗口的相关分析,实现了SAR图像的精确配准。选用星载ALOS-PALSAR和Radarsat-2影像作为试验数据,对提出的方法进行了实验分析。实验结果表明:该方法在无需任何先验知识的情况下,可以全自动完成重复轨道星载SAR数据的快速配准,且精度满足SAR干涉处理等时间序列SAR应用处理的需求,具有较强的鲁棒性。     

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.     

顺轨机载InSAR海面运动舰船成像

研究了顺轨双天线机载干涉合成孔径雷达（InSAR）的海面运动舰船目标成像问题.分析了船体散射点三维运动对舰船目标成像的影响,给出了顺轨InSAR对舰船目标成像的信号处理流程.利用双通道干涉对消处理,检测出存在三维运动的散射点,并对其信号相位进行估计.通过对存在三维运动的散射点实施相位补偿,改善对舰船目标成像效果,InSAR仿真数据的处理结果表明了本文方法的有效性.     

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.     

航磁姿态数据收录系统设计

随着计算机的发展,航空磁法测量的磁补偿方式已从手动补偿转变为自动补偿方式,其磁补偿干扰系数的计算,也在补偿标定飞行中自动完成,磁补偿系数的准确程度是由标定飞行所完成动作(摇摆、俯仰、偏航)的准确性来决定,因而对飞机姿态角度的数据记录和显示,可以为航磁补偿质量的评价提供一种依据,还可以在测区做业的数据处理中,检查航磁探头在测区中工作角度的变化,排除航磁探头进入到死区内的干扰数据；因此在航空物探测量中对飞行姿态数据的采集是很有必要的,该软件应用C++Builder编译系统,实现了在航空磁法测量中对航磁数据、GPS数据、飞行姿态动作数据的实时采集、记录和显示,也为补偿软件的开发提供飞行姿态数据的支持。     

Projecting registration error for accurate registration of overlapping range images

In this paper, we propose a novel algorithm for the automatic registration of two overlapping range images. Since it is relatively difficult to compare the registration errors of different point matches, we project them onto a virtual image plane for more accurate comparison using the classical pin-hole perspective projection camera model. While the traditional ICP algorithm is more interested in the points in the second image close to the sphere centred at the transformed point, the novel algorithm is more interested in the points in the second image as collinear as possible to the transformed point. The novel algorithm then extracts useful information from both the registration error and projected error histograms for the elimination of false matches without any feature extraction, image segmentation or the requirement of motion estimation from outliers corrupted data and, thus, has an advantage of easy implementation. A comparative study based on real images captured under typical imaging conditions has shown that the novel algorithm produces good registration results.     

几种机载InSAR平地效应去除方法的比较研究

论述了InSAR系统平地效应产生的原因,并简述了去除平地效应的常用方法：基于轨道、基于DEM及基于频率的平地效应去除方法。分别将这三种方法应用于机载InSAR系统,经实验结果对比分析表明：基于频率的方法不适用于机载系统,基于轨道、基于DEM的方法适用于机载系统,并得到了满意的结果。     

用平滑薄板样条实现医学图象的弹性配准

医学图象弹性配准是医学图象处理的一个重要研究方向 .目前采用的方法多是手动选择对应标记点 ,然后用薄板样条插值方法计算配准变换 .为了降低对应点的选取误差对配准准确性的影响 ,并克服手动选点操作繁杂、耗时大的问题 ,给出了一种准确、快速、鲁棒性好的配准方法 .即对薄板样条插值方法进行平滑处理 ,并在此基础上采用一种半自动标记点选择方法 .运用此方法进行医学图象的弹性配准 ,得到了理想的结果 .实验表明 ,该方法能有效减弱了对应点位置误差对配准结果产生的影响 ,并能较方便地选择对应点集     

合成孔径雷达及其干涉技术研究进展

合成孔径雷达(Synthetic aperturer adar,SAR)能够在全天候、全天时条件下对地面进行大范围测绘,是现代民用遥感和军事侦察中的重要手段。本文回顾了SAR及干涉合成孔径雷达(InSAR)技术的历史,叙述了SAR由非聚焦到完全聚焦,由光学处理到全数字式处理,由二维测绘到干涉三维测绘的发展历程。通过例举典型系统,介绍了国外机载、空载SAR和InSAR技术的现状,并对我国近年来在该领域取得的进展作了简要介绍。最后,本文给出对SIR—C／X—SAR采集的航天飞机SAR数据处理所得到的成像结果。     

用于高精度三维计算机视觉的图象系统标定和误差补偿

为了对计算机视觉系统进行标定,并削弱由系统模型与真实系统间差异所产生的误差,在详细分析计算机数字成象过程的基础上,提出了一种综合数字成象过程中内部的及外部的,已知的及未知的等各种因素的图象系统标定方法,其标定的具体对象包括光学成象过程中的线性几何投影参数及非线性畸变参数、光电转换过程中的参数和图象信号的D／A及A／D转换过程中的参数等;同时提出了基于该标定方法的三维计算机视觉系统采集三维数据的误差补偿方法及其参数的确定过程。上述方法已经成功地应用于三维计算机视觉系统,并取得了很好的三维精度。