中巴地球资源卫星CCD 影像几何纠正方法比较

由于缺少轨道星历参数和传感器参数, 无法利用共线方程模型完成中巴地球资源卫星影像的精确纠正, 我们在项目中采用多项式纠正、局部区域纠正模型、有理函数模型等近似纠正模型进行中巴地球资源卫星影像纠正对比实验, 对这3 种纠正方法的原理、算法效率、纠正精度等方面进行对比, 通过实验数据分析获得以下结论: 有理函数模型是唯一支持DEM 数据完成中巴地球资源卫星CCD 影像正射纠正的近似纠正数学模型; 多项式纠正模型效率最高; 局部区域纠正模型可以达到很高的纠正精度但不适用于整景影像的纠正。     

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。     

卫星遥感影像RPC参数求解算法研究

针对国内外在求解RPC模型参数算法上需要初值、迭代处理,且求解过程相当复杂的缺憾,提出了基于全球DEM的RPC模型参数求解算法,利用SPOT-5、CBERS-2以及ERS卫星影像进行实验,获得对卫星遥感影像几何处理有意义的结论,并对卫星影像在利用严格成像几何模型求解RPC模型参数时做了控制点格网大小及高程分层数对求解精度的影响实验,得出对卫星遥感影像,采用控制点的格网大小为20×20、高程分层为3可以达到精度和效率的平衡。     

基于计算机仿真技术的CBERS-02B CCD影像几何误差分析

卫星影像的地理坐标定位会受诸多因素的影响而产生误差,各影响因素相互交织,使得误差模型非常复杂。传统的几何误差分析方法中,通常各种变量失去其物理意义,看不到几何纠正误差真实的规律。本文采用计算机仿真技术进行CBERS-02B卫星CCD影像几何误差分析。首先建立影像成像的严密几何模型,在此基础上将影响因素人为引入误差或退化采样精度进行仿真实验和分析,得到CBERS-02B卫星CCD影像畸变的规律。     

星载合成孔径雷达影像正射纠正算法的研究与实现

概述了目前国内外对雷达影像进行正射纠正的算法,分析了星载合成孔径雷达的成像几何原理。阐述了距离-多普勒理论,并将该理论应用到SAR正射纠正,进行了计算机实现,设计了相应的程序模块。用ERS-2产品进行实验的结果表明,这种纠正方法精度比较高,纠正后影像效果好,可以应用到SAR产品的几何处理上。     

全极化合成孔径雷达影像地形纠正及其在雪冰制图中的应用

针对合成孔径雷达（SAR）影像由于地形起伏引起的图像畸变问题,文章提出了基于相干矩阵的全极化SAR影像地形纠正算法,并运用于雪冰制图。该方法首先采用距离多普勒模型建立SAR成像几何模型;然后利用全极化Cloude特征分解方法对全极化SAR图像进行融合,将融合后的SAR图像与模拟图像进行配准提高SAR影像几何定位精度;最后利用投影面积归一化和极化方位角移动补偿技术对地形引起的辐射畸变进行纠正。采用中国长江源区南部唐古拉山中段冬克玛底冰川区域的C波段Radarsat-2全极化SAR数据进行验证,配准模拟SAR和原始SAR影像的控制点方位向和距离向的均方根误差（RMSE）分别为7.765和14.586个像素;经过地形纠正后的地物分类精度达80%以上。结果表明：（1）该方法能够有效消除SAR影像中几何和辐射畸变的影响;（2）地形纠正后的SAR数据在雪冰制图中具有可行性。     

面向西部测图困难地区稀少控制下的TerraSAR-X影像快速正射纠正

针对TerraSAR-X新型雷达卫星影像,基于距离-多普勒(R-D)模型,提出了一种稀少控制下SAR影像正射纠正的方法,并详细阐述了整个处理过程。同时,选用西部横断山脉地区和陕西阎良地区的TerraSAR-X影像作为实验数据,充分利用其高精度的头文件参数信息及5个地面控制点和DEM,分别对其进行正射纠正,阎良地区的纠正精度约为5m,横断山脉地区的纠正精度约为11m,满足了1∶5万的测图精度要求,并对二者的实验结果进行了比较分析。另外,考虑到TerraSAR-X影像数据量大的问题,本文还阐述了运用影像分块处理结合双线性内插原理加快处理大幅SAR影像正射纠正处理的方法,实验表明该方法相对逐像点对SAR影像正射纠正处理,大大提高了处理速度,从而证明了该处理过程的高效性和实用性。     

机载聚束SAR图像定位精度研究

根据机载聚束SAR成像几何关系及线性RD成像算法,对SAR图像的定位精度 进行了深入探讨。由于现有的惯性导航系统大多精度不高,并不能准确提供载机的真实运动 信息,利用这些参数进行成像处理会使目标偏离真实位置。本文主要分析惯性导航系统提供 的载机飞行参数对机载SAR定位精度的影响,建立定位方程并推导出定位误差解析公式。最 后对机载SAR图像定位精度进行仿真分析与实测数据处理验证,处理结果表明载机的视线方 向的速度误差和载机的位置误差是影响SAR图像定位精度主要因素。     

北京一号小卫星几何纠正方法与试验

针对北京一号卫星传感器成像技术特点,在相应的共线方程成像模型基础上,设计了详细的几何纠正流程.该流程包含外方位元素求解和影像重采样两个步骤.在外方位元素求解方面,提出了一种求解外方位元素初始值的计算方法;在影像重采样方面,本文提出了一种求解影像行的迭代方法.最后用本文提出的几何纠正流程对一幅北京一号小卫星影像进行纠正实验,并与传统的多项式纠正进行了精度比较分析,得出本文方法比多项式纠正精度高而且可以消除由于高程引起的投影差.     

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。     

Multi-Observed Block Adjustment for Satellite ImagesWithout Ground Control Points

In order to ensure the accuracy of target area’s ground information,it is necessary to do geometric correction for remote sensing images.Geometric correction has a great influence on the application of remote sensing images.Traditional geometric correction needs ground control points.However,it is difficult to obtain ground control points in some places,such as abroad,western China and desert.To improve positioning accuracy without ground control points,multi\|overlapping block adjustment model is built.Different from traditional method,error equations are built depending on multi\|projection in image space of a single object.In this way,error equations can converge to more accurate solutions.By adjusting the rational polynomial coefficients of each image,the positioning errors in different directions are compensated to a certain extent.Thus the positioning accuracy of remote sensing images is improved.First,block adjustment model and error compensation model are built with RPC coefficients.Then,conjugate gradient algorithm is used to solve the error equations iteratively.Finally the RPC coefficients are adjusted to improve the accuracy of positioning without ground control points.The ZY\|3 data test shows that multi\|overlapping block adjustment model increase the plane positioning accuracy of remote sensing images from 19.8m to 12.9m and the method can effectively improve the absolute positioning accuracy of remote sensing images.     

航片二次几何校正的应用研究

应用ERDAS软件对高分辨率航片进行二次几何校正的研究,从中找出适合各种航片再校正的可行性方法,尤其是对地图采点模式校正方法的科学性、准确性、实用性进行了重点研究,从而获得了一种常规方法无法校正的新校正模式,即综合采点模式。而且,这项技术也完全适用于TM和SPOT等卫星图像的二次几何校正,并且提高了校正精度和速度,是一种比较实用的二次几何校正模型。     

三轴稳定卫星图像系统性几何校正研究

采用三轴稳定方式的地球静止轨道卫星在拍摄地球图像过程中,由于卫星的轨道和姿态角参数的变化,拍摄的图像存在几何畸变,必须通过相应的算法首先对其进行系统性几何校正,消除姿轨参数变化的影响,达到几何畸变校正的目的。叙述系统性几何校正公式推导,并介绍模拟畸变和校正畸变所采用的图像重采样方式,最后给出相关地球圆盘图的模拟和校正结果,通过比较证明校正公式是可行的。     

图像几何畸变精校正研究

卫星传感器在成像过程中会受到诸多因素的影响,使得所获取的影像在几何位置上发生畸变,几何校正的目的就是尽可能消除这些畸变的影响。本文主要研究了用于消除图像几何畸变的两个几何校正模型：多项式模型和MQ模型（Multiquadric Fuctions）,对MQ模型中的系数R进行分析实验提出了一种新的R值的确定方法,与原来的R值相比新的R值能够进一步提高模型的精度;将多项式模型和MQ模型结合使用的Göpfert’s算法引入到卫星影像几何精校正中,实验表明,能够取得比较高的校正精度.     

Robust uncalibrated stereo rectification with constrained geometric distortions (USR-CGD)

A novel algorithm for uncalibrated stereo image-pair rectification under the constraint of geometric distortion, called USR-CGD, is presented in this work. Although it is straightforward to define a rectifying transformation (or homography) given the epipolar geometry, many existing algorithms have unwanted geometric distortions as a side effect. To obtain rectified images with reduced geometric distortions while maintaining a small rectification error, we parameterize the homography by considering the influence of various kinds of geometric distortions. Next, we define several geometric measures and incorporate them into a new cost function as regularization terms for parameter optimization. Finally, we propose a constrained adaptive optimization scheme to allow a balanced performance between the rectification error and the geometric error. Extensive experimental results are provided to demonstrate the superb performance of the proposed USR-CGD method, which outperforms existing algorithms by a significant margin.     

推扫式光学卫星遥感影像产品三维几何模型研究及应用

推扫式光学卫星遥感影像系统校正与精纠正的几何模型通常用一个二维仿射变换模型表示,系统几何校正产品和精纠正产品中仍然包含了地形起伏信息。为了对这些信息加以应用,本文仿照RFM(有理函数模型)用于辐射校正产品几何处理的思路,提出利用RFM对系统几何校正产品、精纠正产品求解RPC参数并进行三维几何处理的技术和方法。分别利用一景北京地区10m和2.5m分辨率SPOT5 HRG各级影像产品进行了正射纠正试验,利用北京地区两景异轨5m分辨率SPOT5 HRG的各级影像产品进行了立体定向试验,结果表明,各级影像产品的三维几何模型可以用三阶分母不相同的RFM替代,与直接应用辐射校正产品影像模型进行正射纠正和立体定向的精度一致。     

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.     

一种基于基本矩阵的相机畸变差自动校正方法

在计算机视觉的应用领域中,为了提高图像量测和3维重建的精度,必须对相机的畸变误差进行修正。为此提出了一种基于基本矩阵的相机径向畸变的自动校正方法,该方法不需要预先获得场景的结构信息和相机的内部参数,仅利用两张影像同名点集之间的内在几何关系,即可求取相机的径向畸变系数,进而可对这两幅图像的畸变误差进行自动校正。试验结果表明,该方法是一种有效的畸变图像校正算法,能够获得到满意的校正结果。     

Chinese satellite photogrammetry without ground control points based on a public DEM using an efficient and robust DEM matching method

Photogrammetry based on high-resolution satellite image can acquire geospatial information within a large area rapidly and timely, but its geopositioning accuracy is highly dependent on ground control points. Under the background of global mapping, a public digital elevation model (DEM) assisted Chinese satellite image geopositioning scheme was proposed to realize satellite photogrammetry without ground control points. To make full use of public DEM advantages of consistent and high accuracy, public DEM was regarded as reference data and matched with the DEM extracted from image, and then the determined transformation parameters were applied to correct direct georeferencing results in object space. A fast least Z-difference method combined with least trimmed squares estimator was proposed to achieve DEM matching, which can not only automatically select corresponding point determination model, but also self-adaptively detect and eliminate difference between DEMs. Multi-groups of comparative experiments using Mapping Satellite-1 and ZiYuan-3 surveying satellite images were designed. Experimental results show that the DEM assisted geopositioning scheme exploits advantages of reference DEM, which can greatly improve the accuracy of photogrammetry without ground control points to a relatively high level. The geopositioning accuracy of image is largely determined by, but not confined to, the accuracy of reference DEM, but it is slightly affected by the resolution of reference DEM. If target DEM resolution is relatively high, the geopositioning accuracy of a single image assisted by Shuttle Radar Topography Mission (SRTM) DEM can satisfy the accuracy requirements of 1:50,000 scale mapping perfectly. This scheme also has good robustness and high computational efficiency.