高斯-克吕格投影坐标系下POS角元素的转换方法

我国的地形测量坐标系通常采用高斯-克吕格投影坐标系,由于地球曲率和子午线偏差的影响,POS系统提供的传感器姿态角向影像外方位角元素的转换过程中存在误差,需要引入一个额外的补偿矩阵进行修正.从分析地球曲率和子午线偏差对影像外方位角元素的影响入手,推导补偿矩阵的严密计算公式,并完善了POS角元素的转换公式.通过对带有POS...     

POS影像外方位元素相关性对模型上下视差理论精度的影响

推导了直接利用影像外方位元素重建立体模型时上下视差的理论精度公式,利用两组带POS数据的实际航摄影像进行了试验。结果表明,当顾及影像外方位元素间的相关性时,模型上下视差的理论精度可以正确反映影像外方位元素的真实精度;视外方位元素为独立参数时,所估算的模型上下视差的理论精度非常低,且存在明显系统误差,不能正确评价影像外方位元素的实际精度。因此,为了能在摄影测量中合理使用POS测定的影像外方位元素,在提供影像外方位元素值的同时应给出外方位元素参数间的协方差矩阵。     

POS数据用于立体模型恢复时的上下视差分析

从连续法相对定向原理出发，推导了直接由像片外方位元素恢复立体模型时模型点上下视差的计算公式，用模拟数据验证了计算方法的正确性，并对两组不同摄影比例尺的实际航摄像片进行了试验。通过比较利用GPS辅助光束法区域网平差获得的像片外方位元素和POS提供的像片外方位元素重建立体模型所产生的模型上下视差，分析了POS系统误差对模型上下视差的影响。结果表明，直接利用POS提供的像片外方位元素进行安置元素测图会出现作业员难以忍受的模型上下视差，不能满足地形测图的规范要求。     

机载POS的航空影像自动校正的方法与实现

针对每次航空摄影有大批量的影像需要进行几何校正处理,分析了正射纠正算法的全过程,提出利用索引矩阵来进行图像整体运算,利用航空相机的内方位元素和POS系统所提供的外方位元素,用IDL编程开发了航空影像的全自动批处理正射校正的软件,并对其处理结果与ERDAS9.1的LPS所做出来的正射影像图进行比较。     

基于POS数据的核线影像生成方法

提出一种对已知外方位元素的立体影像实施灰度重采样生成核线影像对的方法,推导了核线影像与原始影像之间的严密几何关系,并利用一组摄于某山区的1∶3000比例尺实际航空影像验证了所建立几何关系的正确性和方法的可行性。试验表明,利用光束法区域网平差和经检校后的POS影像外方位元素生成的核线影像对与基于常规相对定向方法所生成的核线影像对具有相同的质量,同名点的上下视差在1像元以内,完全可以满足摄影测量立体观测的要求;而采用未经检校的POS影像外方位元素所生成的同名核线影像对带有约70像元的上下视差,无法用于立体观测。     

两步解法用于求解线阵CCD影像外方位元素

在线阵CCD影像外方位元素的求解过程中,外方位元素之间的相关性,导致法方程病态,最小二乘估计值误差较大。本文在分析以往解决方法的基础上,提出采用两步解法求解线阵CCD影像的外方位元素。该算法的实质是选择一个比单位矩阵更合适的正则化矩阵。试验结果表明该算法能有效地克服线阵CCD影像外方位元素间的相关性,定位精度较高,定向点精度在1个像素内,检查点精度在1.5个像素内。     

Relative orientation based on multi-features

In digital photogrammetry, corresponding points have been widely used as the basic source of information to determine the relative orientation parameters among adjacent images. Sometimes, though, the conventional relative orientation process cannot be precisely implemented due to the accumulation of random errors or in the case of inadequate corresponding points. A new relative orientation approach with multiple types of corresponding features, including points, straight lines, and circular curves, is proposed in this paper. The origin of the model coordinate system is set at the projection center of the first image of a strip, and all of the exterior orientation parameters, except φ and ω of the first image, are set at zero. The basic models of relative orientation with corresponding points, straight lines, and circular curves are discussed, and the general form of a least squares adjustment model for relative orientation based on multi-features is established. Our experimental results show that the proposed approach is feasible and can achieve more reliable relative orientation results than the conventional approach based on corresponding points only.     

考虑内定向误差的外方位元素精度分析

在对数据质量的要求越来越严格的今天,我们对数据质量的评价也必须越来越系统、可靠。本文就是在系统分析的基础上推导出了求解外方位元素的误差传递模型,并从中分析了内定向误差对外方位元素精度的影响,从而改进和完善了外方位元素精度的评定方法,使得外方位元素精度的评定具有更高的精确性和可靠性。     

Development of a Coordinate Transformation method for direct georeferencing in map projection frames

This paper develops a novel Coordinate Transformation method (CT-method), with which the orientation angles (roll, pitch, heading) of the local tangent frame of the GPS/INS system are transformed into those (omega, phi, kappa) of the map projection frame for direct georeferencing (DG). Especially, the orientation angles in the map projection frame were derived from a sequence of coordinate transformations. The effectiveness of orientation angles transformation was verified through comparing with DG results obtained from conventional methods (Legat method¹ and POSPac method²) using empirical data. Moreover, the CT-method was also validated with simulated data. One advantage of the proposed method is that the orientation angles can be acquired simultaneously while calculating position elements of exterior orientation (EO) parameters and auxiliary points coordinates by coordinate transformation.These three methods were demonstrated and compared using empirical data. Empirical results show that the CT-method is both as sound and effective as Legat method. Compared with POSPac method, the CT-method is more suitable for calculating EO parameters for DG in map projection frames. DG accuracy of the CT-method and Legat method are at the same level. DG results of all these three methods have systematic errors in height due to inconsistent length projection distortion in the vertical and horizontal components, and these errors can be significantly reduced using the EO height correction technique in Legat’s approach. Similar to the results obtained with empirical data, the effectiveness of the CT-method was also proved with simulated data.     

Calibration of digital camera integration accuracy for low-cost oblique aerial photogrammetry

This work describes a calibration process for inexpensive consumer cameras integrated into a low cost and compact aerial multi-view imager for remote sensing and photogrammetry. The main advantage of this design is to make the filming component lightweight and rapidly deployable, as well as reducing cost when compared with mainstream commercial oblique imagery. An in situ flight test was carried out in Guiyang. In that experiment, a meridian convergence-based approach was adopted to adjust preprocessing, the residue error and the captured images’ exterior orientation linear and angular parameters were calculated by means of the direct geo-referencing approach yielding a favorable outcome for exterior orientation linear parameters of the camera, around 0.2–0.3 m deviation from the actual measured results at 1000 m flight above ground level. The camera’s exterior orientation angular parameters φ, ω whose difference compared with the standard aerial aero triangulation approach reached a high accuracy level within the intended endurance of 0.005°. These results indicate that the compact implementation of the oblique aerial imager comprised of consumer level off-the-shelf digital cameras achieved competitive accuracy at a low cost and high versatility.     

一种非量测相机近景影像外方位元素解算方法

本文提出了一种角椎体法和共线方程法联合解算非量测相机影像外方位元素的方法。工程应用证明该方法求解像片的外方位元素具有计算速度快、收敛性强、计算精度高等优点。     

基于单位四元数的空间后方交会解算

介绍四元数的概念及运算性质,提出基于单位四元数的空间后方交会解算方法并给出计算公式。该方法利用单位四元数表示旋转,根据最小二乘原理,通过矩阵运算先求出单位四元数解析解,再获取旋转矩阵,得到角元素值;最后求出撮站点的坐标。此法不需提供外方位元素初始值,并且推导过程中不涉及共线条件方程的线性化。通过算例证明方法的正确性与可靠性。     

Error analysis of exterior orientation elements on geolocation for a Moon-based Earth observation optical sensor

ABSTRACT

The Moon is a potential new platform for Earth observation. The advantages of its large-scale observational scope, long temporal duration, and multi-layer detecting of the Earth will undoubtedly advance our understanding of the Earth system. To carry out the observations from a Moon-based optical sensor, the geolocation error caused by exterior orientation elements need to be investigated. This paper analyses the error effects of exterior orientation elements on geolocation for an optical sensor. To estimate the error, we present a geometric image model and utilise some parameters to measure the image offsets. Through a large number of numerical simulations, the results demonstrate that the image offsets are not obvious influenced by the distance and observation angle at mid-high latitude of the Moon and have linear correlation with the increasing errors of the exterior orientation elements. Further, the relationship between the spatial resolution and errors of exterior orientation elements are revealed. Finally, the error characteristics for Moon-based Earth observation are discussed. It is expected that the conclusion drawn in this paper could support the study of a Moon-based Earth observation optical sensor.     

几内亚BOKE558铝土矿勘探独立坐标系的建立及转换研究

建立地方独立坐标系的主要元素是中央子午线、投影面和参考椭球。建立独立坐标系有三种方法：中央子午线移到城市或工程建设地区中央,归化高程面提高到该地区的平均高程面;采用抵偿高程面;只移动中央子午线。以工程实例得出国家坐标系与地方独立坐标系之间转换的可靠、简便方法。     

POS辅助航空摄影测量多片直接对地目标定位的质量分析

以基于共线条件方程的空间前方交会理论为基础,建立POS辅助航空摄影测量的多片直接对地目标定位及其质量评价模型,并对摄自不同地区多种摄影比例尺的实际影像进行试验。试验结果表明:利用POS系统提供的影像外方位元素进行多片直接对地目标定位,完全能够满足我国现行规范对不同比例尺各种地形测绘的精度要求;并且,随着每航带交会影像数目和航带条数的增加,目标点的定位精度逐渐提高,多片直接对地目标定位的可靠性亦逐步提高。因此,利用POS系统提供的影像外方位元素进行多片直接对地目标定位时,综合考虑待定点在全测区内的所有成像影像是必要的。     

Insights into the affine model for high-resolution satellite sensor orientation

As a model for sensor orientation and 3D geopositioning for high-resolution satellite imagery (HRSI), the affine transformation from object to image space has obvious advantages. Chief among these is that it is a straightforward linear model, comprising only eight parameters, which has been shown to yield sub-pixel geopositioning accuracy when applied to Ikonos stereo imagery. This paper aims to provide further insight into the affine model in order to understand why it performs as well as it does. Initially, the model is compared to counterpart, ‘rigorous’ affine transformation formulations which account for the conversion from a central perspective to affine image. Examination of these rigorous models sheds light on issues such as the effects of terrain and size of area, as well as upon the choice of reference coordinate system and the impact of the adopted scanning mode of the sensor. The results of application of the affine sensor orientation model to four multi-image Ikonos test field configurations are then presented. These illustrate the very high geopositioning accuracy attainable with the affine model, and illustrate that the model is not affected by size of area, but can be influenced to a modest extent by mountainous terrain, the mode of scanning and the choice of object space coordinate system. Above all, the affine model is shown to be both a robust and practical sensor orientation/triangulation model with high metric potential.     

像底点用于POS系统直接对地目标定位

根据像底点与航摄像片外方位角元素的几何关系,本文提出利用像底点求解IMU视准轴误差,以提高POS系统直接对地目标定位精度的方法,并用一组实际飞行的数据进行了试验。结果表明,该方法可有效提高POS系统直接对地目标定位的精度,而无需布设特定的检校场和地面控制点。对带POS系统的城区大比例尺航空影像对地目标定位有一定实用价值。     

基于CGCS2000的城市平面坐标系最佳选取

本文以CGCS2000启用后城市平面坐标系的选取和确定为研究内容,提出了以投影改正平方和最小与投影变形大于2.5cm/km的点数最少为原则进行最佳中央子午线和抵偿高程面选取的方法,并以武汉市为例,通过实际控制点的CGCS2000大地坐标予以实现.相比常规方法,该方法更科学、严谨,比较客观地反映了区域地形起伏对平面坐标系...     

POS数据的上下视差误差源检测及误差补偿回归模型

分析POS数据存在系统误差的主要原因,推导基于POS的立体像对相对定向模型,建立POS系统误差回归补偿模型。三个不同比例尺测区试验数据的结果表明：POS系统提供的外方位元素中角元素误差是引起模型上下视差的主要误差源;利用回归补偿模型对POS数据进行改正后模型上下视差明显减小;在无需区域网平差的情况下,直接通过相对定向消除POS系统误差,定位精度有较大提高,从而证明该补偿模型的正确性与可行性。     

航空摄影测量中立体模型的重建

This paper describes the operational issues and basic technical requirements of modern aerial photogrammetry. The accuracy of photogrammetric point determination and the y-parallax at corresponding model points is analyzed when stereo models are reconstituted by using the exterior orientation elements of aerial images. Real aerial photographs, at image scales from 1：2 500 to 1：6 0000, with DGPS/IMU data taken from various topographies in China were processed by our POS-supported bundle block adjustment program WuCAPS. The empirical results verified that the accuracy of the exterior orientation elements from bundle block adjustment meets the requirements of the specifications of topographic mapping. However, the accuracy of the exterior orientation elements determined by POS fails to meet the requirements of the specifications of topographic mapping.