不同分辨率线阵卫星影像联合区域网平差

不同影像联合区域网平差可以提高影像利用率与应急几何处理效率,以达到利用少量控制点对影像进行定位的目的,该文以严格成像模型为基础,将姿轨系统误差描述为时间的二次多项式,通过引入带权虚拟观测值改善法方程状态来克服定向参数之间的相关性,并给出各类观测值的定权方法,推导出区域网平差模型,并对不同分辨率影像进行联合区域网平差。结果表明:控制点个数并非越多越好,对本实验区域而言,采用SPOT-5影像进行几何定位,周边布设4个控制点即可消除大部分系统误差;影像分辨率影响像点坐标量测精度,不同分辨率影像联合平差时可以通过权值设定及增加影像重叠度方法改善几何定位精度。     

资源三号卫星影像DEM提取与精度分析

为提高国产遥感卫星影像定位精度,提取高精度DEM,该文基于卫星遥感的成像模型和间接平差理论,利用有理函数模型和像面仿射变换模型,构建了卫星影像平差数学模型;利用该数学模型对资源三号卫星立体影像进行了平差处理,建立了研究区域DEM。分析结果表明:DEM在无控制点情况下,平地区域平面精度达到6.12m,高程精度达到8.39m;山地区域平面精度达到6.20m的,高程精度达到8.62m,数据精度能够满足1∶50000比例尺地形图测图标准和要求。研究结果验证了国产卫星数据的定位精度。     

基于已有控制资料的正射影像自动更新

高分辨率遥感影像作为地理国情监测的基础数据,其新数据获取后的变化检测与适时更新是地理国情实现动态监测的关键。该文将已有的正射影像和数字高程模型作为新获取高分辨率卫星影像的控制资料,结合通用成像模型的有理多项式模型,首先实现高分辨率卫星影像与已有DOM/DEM之间的特征提取和匹配,然后利用RFM模型的区域网平差对匹配结果进行粗差剔除,从而实现高分辨率卫星影像的对地定位,最终实现正射影像更新。实验证明该方法可提高匹配精度与定向参数的可靠性。     

山区地形星载SAR影像的几何纠正

随着搭载合成孔径雷达的各种卫星不断发射,SAR的研究越来越受到重视。由于SAR数据独特的成像方式,山区地形的星载SAR图像几何形变十分复杂。通常应用控制点,采用多项式拟合的方法已经无法将其改正。依据SAR的几何成像模型,利用有关卫星轨道参数和数字高程模型,进行山区地形SAR影像的几何纠正研究。研究利用少量轨道参数和DEM数据,通过坐标变换和投影成像误差纠正建立正确的坐标位置,并采用邻近元采样法完成几何纠正。以上方法应用于山区ERS-1/SAR影像的处理试验结果表明,该方法能够用于山区复杂地形的几何纠正,其误差小于2个像元。     

CBERS-02B星HR数据几何纠正模型研究

作为目前我国发射的分辨率最高的民用卫星,CBERS-02B星HR数据在大比例尺资源环境调查和基础地理信息更新等方面发挥着重大的作用。为了推广其应用,本文在不能获取卫星轨道星历参数和传感器参数的情况下,对覆盖两种不同地形类别的CBERS-02B星HR影像1级数据进行了多项式、投影变换、RPC等几种不同几何模型的纠正试验,并进行了精度分析与评定。本次试验结果表明:当控制点数量不多时,3阶多项式纠正精度相对较高,对于地形起伏较小的地区,所需的控制点数量为20个左右就可获取较高的精度,而对地形起伏较大的地区,控制点的数量则需要30个以上才能获得较高的精度;无足够控制点时RPC模型纠正精度不理想。     

基于WorldView-2制备大野口流域高分辨率DEM及精度分析

在全野外GPS地面控制点基础上,对WorldView-2影像自带RPC文件进行校正,利用数字摄影测量软件系统在立体模型上通过影像自动匹配技术快速提取黑河流域上游大野口子流域1∶5 000比例尺数字高程模型(DEM)。由于区域地形复杂、交通不便,研究区南部无地面控制点覆盖。基于立体模型交互式操作,匹配60个均匀分布高精度影像连接点,提高了DEM自动提取精度。并在对阴坡森林覆盖区、大野口水库等重点区域进行DEM编辑基础上,辅助地形特征点和线数据提高了成果精度。由15个外业控制点、12个模型保密点组成的检查点进行定量DEM验证,结果表明:两组高程中误差最大为1.9 m,达到该比例尺山地一级精度2.5 m的要求。
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SAR影像配准中控制点粗差剔除方法研究

复数影像配准是雷达干涉测量中的关键步骤之一,而配准中选取的控制点往往存在粗差,影响配准精度。分析了SAR影像配准时控制点粗差产生的原因,提出了方差因子检验和Baarda数据探测法剔除控制点粗差的方法,建立了基于可靠控制点计算影像纠正的几何变换模型。利用ENVISAT卫星ASAR图像对所提方法进行了验证,结果表明,影像配准的精度达到了0.1像素,粗差剔除后SAR影像配准精度有明显提高。     

一种影像增强器失真图像的校正方法

针对基于X线透视的骨科手术导航系统中影像增强器图像失真的问题,在多项式变换校正影像增强器失真图像的基础上,提出了基于正交多项式和加权正交多项式变换的影像增强器失真图像校正方法.利用正交多项式的正交特性和递推关系,提高影像增强器失真图像校正的精度、速度和灵活性;加权正交多项式变换中考虑控制点对不同像素点影响的不同,改善图像的局部形变.实验数据表明,相同阶数的正交多项式方法比多项式方法精度高,加权正交多项式方法则精度更高,能用较低阶的加权正交多项式实现较高的精度.在骨科手术导航系统中,作者利用三阶加权正交多项式方法校正影像增强器透视图像,降低了图像几何失真给病人空间与图像空间配准带来的误差,提高了手术定位的精度.     

“高分一号”卫星数据几何校正研究

运用野外采集的GPS数据研究几何校正模型和控制点数量对4景"高分一号"高分辨率相机数据的几何校正精度影响,此项研究有利于合理使用"高分一号"卫星数据,为国产卫星数据的应用和推广起到一定的促进作用。分别运用多项式模型和有理函数模型对"高分一号"数据进行几何校正,运用事先布置好的检查点与校正后影像上的同名地物点进行精度分析,实验表明运用有理函数模型对"高分一号"数据进行几何校正会取得较好精度。分别运用25、20、15、10、5、1个和无控制点对4景"高分一号"数据进行有理函数模型的几何校正。综合考虑人力、耗时、精度等因素后得出结论:如果影像中山区不多时,运用5个控制点进行校正可以取得较好的效果,当山区比较密集时,可以适当增加控制点数量到10个。     

基于卡尔曼滤波的Landsat-8卫星影像几何精校正

卡尔曼滤波是一种递推线性最小方差估计算法,被广泛应用于GPS动态数据处理、组合导航和通信与信号处理等领域。本文将卡尔曼滤波引入卫星影像几何精校正处理中,以Landsat-8卫星影像为例,利用卡尔曼滤波方法和地面控制点构建运动方程和测量方程,实现了对卫星星历和姿态数据的修正。实验证明,相比于传统最小二乘平差法,该方法使用较少的控制点即可达到稳定的精度,降低了几何精校正对控制点数量的依赖,具有较高适用性。     

A WTLS-based rational function model for orthorectification of remote-sensing imagery

The rational function model (RFM) is widely applied to orthorectification of aerial and satellite imagery. This article proposes a new method named Ortho-WTLS to solve the RFM in remote-sensing imagery orthorectification. Based on a weighted total least squares (WTLS) estimator, the proposed method allows one to handle coordinates of ground control points (GCPs) that contain errors and are of unequal accuracies. This situation occurs, e.g. if GCPs are automatically selected. In the proposed model, first, the relationship of two linearization methods for an RFM with errors contained in GCPs is investigated and results in a hybrid linearization. Next, based on WTLS, RFM coefficients are estimated with an iterative computation function. Finally, the performance of the Ortho-WTLS method thus obtained is investigated using simulated images and remotely sensed images by collecting GCPs with varying errors. Experimental results show that the Ortho-WTLS method achieves a more robust estimation of model parameters and a higher orthorectification accuracy when compared with standard LS-based RFM estimation. We conclude that the quality of GCPs has a large impact on the accuracy and that an increasing number of low-precision GCPs may lead to a decrease in orthorectification quality.     

The problem of AVHRR image navigation revisited

In this study, Earth location errors in AVHRR satellite data and methods for their correction are examined with particular application to oceanic regions far removed from ground control. A general correction procedure, using landmarks or Ground Control Points (GCPs) and taking into account landmark uncertainties, is presented. Correction functions arc derived as expansions for any complete basis. Operationally-available estimates of Earth location are used as a first-guess in developing the correction procedure. In particular, polynomial expansions are used to represent the correction functions which provide the basis for renavigating the satellite data. The coefficients of the polynomial expansions are obtained using the method of least-squares. The stability of the correction procedure with respect to. local errors in navigation, (i.e. within a scene) and how to select the correct order of the correction polynomials are examined. Uncertainty in extrapolating navigation corrections over remote regions is examined and quantified. The importance of landmark uncertainty in degrading renaviga-tion accuracy is also addressed. Several parameters are introduced to optimize the choice of GCPs and their distributions. The procedures which are developed are then applied to simulated and actual AVHRR imagery. Finally, the impact of local errors in navigation, which most likely arise from rapid variations in spacecraft attitude, on renavigation accuracy is emphasized and one possible solution proposed.     

Geometric accuracy assessment of the orthorectification process from very high resolution satellite imagery for Common Agricultural Policy purposes

This study has, as its main aim, the assessment of different sensor models to achieve the best geometric accuracy in orthorectified imagery products obtained from IKONOS Geo Ortho Kit and QuickBird basic imagery. The final orthoimages are compared, both geometrically and visually, with the panchromatic orthophotos based on a photogrammetric flight with an approximate scale of 1 : 20 000, which are now used for the European Union Common Agricultural Policy in Andalusia (Spain). Two‐dimensional root mean square (RMS_2d) errors in independent check points are used as accuracy indicators. The ancillary data were generated by high accuracy methods: (1) check and ground control points (GCPs) were measured with a differential global positioning system and (2) an accurate digital elevation model was used for image orthorectification. Two sensor models were used to correct the satellite data: (1) a three‐dimensional (3D) rational function refined by the user with zero‐ (RPC0) or first‐(RPC1) order polynomial adjustment and (2) the 3D Toutin physical model (CCRS). For the IKONOS image, the best results in the final orthoimages (RMS_2d of about 1.15 m) were obtained when the RPC0 model was used. Neither a large number of GCPs (more than nine), nor a better distribution of them, improved the results obtained with the RPC0. For the QuickBird image, the CCRS model generated the best results (RMS_2d of about 1.04 m), although it was sensitive to the number and distribution of the GCPs used in its computation.     

低空间分辨率多源遥感数据的空间一致性分析和相对几何校正

多源低空间分辨率遥感数据在空间上的一致性对于其在全球变化研究中的集成使用有非常重要的意义。对此,以公认几何精度较高的MODIS数据为基准,对NOAA/AVHRR、FY-3/VIRR、FY-3/MERSI、FY-2/VISSR这4类国内外常用的低空间分辨率传感器的L1B数据进行了一系列相对几何精度评价和多项式相对几何校正的实验。相对几何精度评价的结果表明:MODIS数据与这4类L1B数据在几何精度上的偏差都比较大。在此基础上,选取少量均匀分布的控制点并采用不同阶数的多项式几何校正模型对多源数据进行空间一致性校正。校正结果表明:低阶的多项式几何校正模型就能对各种待校正数据的几何精度有显著的提升,使其与基准数据在空间上达到一致,满足全球变化研究对低分辨率多源遥感数据在空间一致性上的需求。     

Geometric correction accuracy of IRS-1D PAN imagery using topographic map versus GPS control points

Geometric correction accuracy of IRS-1D panchromatic imagery was investigated using GPS- and 1?:?25?000 scale topographic map-derived control points. The differentially corrected GPS-derived coordinates provided markedly more accurate results than did uncorrected handheld GPS- and map-derived GCPs. The rms error value of differentially corrected GPS-derived control points based on second-degree polynomial was in the order of ±3?m. Geometric corrections made with second-degree polynomials, using both the map- and uncorrected handheld GPS-derived control points, yielded rms error values in the order of ±5?m. The results revealed that the uncorrected handheld GPS-derived control points can be a valuable alternative to planimetric control for geometric correction of IRS-1C/D panchromatic imagery with one-pixel size accuracy.     

Detection of attitude constant error and in-orbit calibration for the three-line CCD sensor of the ZY-3 satellite

In-orbit calibration of satellite optical sensors is of crucial importance for improving the accuracy and stability of high-resolution satellite stereo mapping and positioning. For the in-orbit calibration of Ziyuan 3 (ZY-3), the first Chinese three-line stereo mapping satellite, a rigorous imaging geometric model of the three-line sensors is established and the internal systematic error is modelled during analysis of the satellite structure and charge-coupled device (CCD) array. To improve the accuracy and stability of the in-orbit calibration, a new trajectory model, piece-point with weight polynomial model, is used and compared with models in current use. In addition, an attitude constant error model is constructed and applied to reduce attitude errors and provide a more accurate initial attitude value, thus increasing the accuracy and stability of the in-orbit calibration. In addition, ground control point (GCP) stripes, established by partitioning GCPs into stripes, are proposed and used to eliminate random errors during in-orbit calibration. Finally, in-orbit calibration is performed for single and multiple sensors and the result of the calibration is assessed using GCPs and checkpoints. Based on the calibration result, variations of the three-line CCD array on ZY-3 are calculated and analysed in the along- and cross-track directions.     

Spatial accuracy of orthorectified IKONOS imagery and historical aerial photographs across five sites in China

High‐resolution (?1?m) satellite imagery and archival World War II era (WW2) aerial photographs are currently available to support high‐resolution long‐term change measurements at sites across China. A major limitation to these measurements is the spatial accuracy with which this imagery can be orthorectified and co‐registered. We orthorectified IKONOS 1?m resolution GEO‐format imagery and WW2 aerial photographs across five 100?km² rural sites in China with terrain ranging from flat to hilly to mountainous. Ground control points (GCPs) were collected uniformly across 100?km² IKONOS scenes using a differential Global Positioning Systems (GPS) field campaign. WW2 aerial photos were co‐registered to orthorectified IKONOS imagery using bundle block adjustment and rational function models. GCP precision, terrain relief and the number and distribution of GCPs significantly influenced image orthorectification accuracy. Root mean square errors (RMSEs) at GCPs for IKONOS imagery were <2.0?m (0.9–2.0?m) for all sites except the most heterogeneous site (Sichuan Province, 2.6?m), meeting 1:12?000 to 1:4800 US National Map Accuracy Standards and equalling IKONOS Precision and Pro format accuracy standards. RMSEs for WW2 aerial photos ranged from 0.2 to 3.5?m at GCPs and from 4.4 to 6.2?m at independent checkpoints (ICPs), meeting minimum requirements for high‐resolution change detection.     

基于稀少控制IKONOS的近海岸岛礁立体影像定向研究

针对我国岛礁控制现状,进行了基于稀少控制IKONOS的近海岸岛礁立体影像区域网平差定向实验,通过对不同控制方案的定向精度分析,提出了稀少控制的岛礁影像控制点布设方案,为我国近、远海重点岛礁的立体影像定向测图提供参考。     

Geocoding RISAT-1 MRS images using bias-compensated RPC models

The purpose of this paper is two-fold. First, the use of the rational polynomial coefficients (RPCs) model is studied for geocoding of Medium Resolution Scan (MRS) ground range (GR) images from the RISAT-1 SAR mission. As the GR images are obtained after many preprocessing image corrections for topographic effect, range cell migration, etc., the number of ground control points (GCPs) required for orthorectification to meet desired geometric quality needs to be established. This assumes importance due to difficulty in visual identification of the GCPs in 18 m-resolution MRS SAR images. Second, three possible methods of bias-compensated RPC models are studied for geocoding. These cases are (A) modified RPC with shift bias, (B) regenerated RPC with shift bias, and (C) regenerated RPC with affine transform model. Experiments are carried out with a set of eight scenes acquired over planar regions especially to avoid the impact of SAR-specific geometric effects such as foreshortening and layover. Geometric accuracy of the orthoimages obtained from these cases is verified at GCPs used for processing as control points and at new GCPs used as check points. It is observed that the modified RPC with the shift bias case required more GCPs to meet the desired geopositioning accuracy. Even though both the regenerated RPC models have shown near similar performance, the regenerated RPC with shift bias compensation is found to reach the required geopositioning accuracy with least number of the GCPs, suggesting it as a strong candidate for realizing operational high precision RISAT-1 geocoded products for multi-temporal data analysis.