PARALLAX BAR HEIGHT MEASUREMENTS FROM LARGE FORMAT CAMERA PHOTOGRAPHY

The accuracy of heighting from Large Format Camera (LFC) stereo-photographs of the New England area was evaluated using a conventional mirror stereoscope equipped with × 6 binocular eyepieces and a precision parallax bar. It was discovered that a large differential ω had to be removed before acceptable height results could be obtained. Enlarged portions of the LFC photographs covering city areas of Boston, Massachusetts and Providence, Rhode Island could be used to produce accurate height results. It was concluded that analogue mapping from LFC photography using simple instruments could be economically carried out at a scale of 1:100000 or smaller, with a contour interval of 100 m to 120 m.     

DETERMINING AND PRESENTING THE THIRD DIMENSION OF A CITY CENTRE: A PHOTOGRAMMETRIC APPROACH

The heights of buildings in the city centre of Glasgow have been measured by photogrammetric methods. A comparison of the heighting accuracy with ground checks obtained by the use of a reducing telemeter indicates the possibilities of achieving accurate results by means of photogrammetric instruments and methods. An attempt to present the third dimension of the city on paper has also been made with the Stereosimplex He and the Perspektomat coupled together to form a drawing system. It is hoped that this approach can be further developed so that it will be of use to town planners, urban geographers and others with an interest in the rapid collection of accurate data about cities.     

HEIGHTS FROM PARALLAX BAR AND COMPUTER

The results are given of a series of tests where a stereoscope, parallax bar, and digital computer were used to derive accurate heights of a large number of points in several models. After suitable modifications of the standard formula, the conclusion is reached that results approaching those obtained with plotting machines are possible, provided that the observer has sufficient experience of stereoscopic measurement.     

AN EXACT PROCEDURE FOR NUMERICAL ORIENTATION OF A PLOTTING INSTRUMENT

An exact theory is developed and a method of solution is described for the computation of relative and, if so desired, absolute orientation settings in a plotting instrument. The Ω drum of the plotting instrument is used to remove vertical parallax “in the model” at each of the standard orientation points in turn; this is also done at the control points if the absolute orientation is to be found simultaneously. After removal of parallax at each point, the X, Y, Z settings are recorded. From these data the final instrument settings are computed. The (non-linear) condition equations are solved using a simplified form of the Newton method generalised to n dimensions. No restrictions are placed on any of the initial settings of the instrument. In view of the continuously increasing ease and speed of access to electronic computers, it seems desirable to ignore all assumptions of small tilts and flat ground which are usually made in order to simplify the arithmetic and to aim instead at an exact solution in one computation.     

半全局约束下的多基线立体影像MVLL匹配方法

多视铅垂线轨迹法（multi-view vertical line locus,MVLL）能够以物方地面铅垂线为几何约束,匹配获取物方空间点的最佳高程,是一种实用的多基线立体影像匹配方法。针对MVLL匹配方法中的物方空间点独立匹配、缺少整体性约束问题,将物方空间局部光滑特性应用至匹配过程,提出了一种半全局约束下的多基线立体影像MVLL匹配方法。首先,将物方空间点沿地面铅垂线上的准确高程搜索,等效至像方空间沿核线方向上的准确视差搜索;其次,采用MVLL匹配方法计算物方空间点在多张影像上的等效像方匹配测度;然后,采用半全局匹配法（semi-global matching, SGM）对匹配测度进行多路径聚合分析,得到物方空间局部光滑约束下的等效视差图;最后,将等效视差图转化为物方空间点匹配高程,并对多基线立体影像进行多分辨率匹配处理,实现整体最优条件下的MVLL匹配。采用多类型地形特征与局部区域影像进行匹配实验与对比分析,实验结果表明,所提方法能够对多类型地形特征的物方空间匹配测度进行优化,获取更加可靠的匹配结果,具有更高的影像匹配性能。     

DEVELOPMENT OF AN INEXPENSIVE IMAGE SPACE PLOTTER

This paper discusses an inexpensive, analytical system designed for a forestry application of photogrammetry. It is presented in two parts. Part I describes an image space plotter that was built in New Zealand and is operating there. The system uses a digitising table to collect left-hand photograph co-ordinates. an encoded micrometer bar to measure × parallax and a mirror stereoscope for viewing photographs. The mathematical, formulation is based on simplifications first suggested by E. H. Thompson. Good accuracy in ground heights can be achieved by the system, but only poor accuracy in planimetric co-ordinates. The cause of poor planimetric accuracy is investigated in Part II. Two error sources are apparent: the simplified analytical theory and systematic errors from the digitising table. Part II also investigates the relationship between random errors in image co-ordinate measurements and system accuracy.     

卫星摄影测量中偏流角修正余差改正技术

本文基于立体影像摄影机理,对偏流角修正的剩余误差导致的上下视差进行了分析,建立了立体相机偏流角余差改正的数学模型,推导出偏流角余差影响上下视差的误差方程,并重点从相机参数在轨标定和光束法平差中低频误差补偿两方面提出解决措施。理论分析与实际卫星影像试验表明,偏流角改正余差对上下视差影响较大,必须通过相机参数在轨标定和低频误差补偿两方面予以改正,才能保证全球范围无地面控制点目标定位精度的一致性。     

基于小波影像金字塔的影像自动匹配

数字影像高精度快速匹配是遥感影像3维信息提取的关键技术之一，文中对如何实现数字影像自动化匹配进行了研究，提出了一种基于小波影像金字塔的数字影像自动匹配方法。该方法在生成小波影像金字塔的基础上，利用交叉相关算法实现不同影像金字塔同一层影像间的匹配，利用视差控制将同名点从金字塔高层影像向低层影像进行传递。利用该方法对具体的SPOT影像进行了实验，表明基于小波影像金字塔的数字影像自动匹配方法具有较好的效果。     

Tuning a gravimetric quasigeoid to GPS-levelling by non-stationary least-squares collocation

This paper addresses implementation issues in order to apply non-stationary least-squares collocation (LSC) to a practical geodetic problem: fitting a gravimetric quasigeoid to discrete geometric quasigeoid heights at a local scale. This yields a surface that is useful for direct GPS heighting. Non-stationary covariance functions and a non-stationary model of the mean were applied to residual gravimetric quasigeoid determination by planar LSC in the Perth region of Western Australia. The non-stationary model of the mean did not change the LSC results significantly. However, elliptical kernels in non-stationary covariance functions were used successfully to create an iterative optimisation loop to decrease the difference between the gravimetric quasigeoid and geometric quasigeoid at 99 GPS-levelling points to a user-prescribed tolerance.     

在轨卫星无地面控制点摄影测量探讨

摄影测量卫星采用商用级星敏感器构成的测姿系统,其姿态测量存在不可忽视的低频和＂慢漂＂系统性误差,使得经过在轨标定后的星敏感器和三线阵CCD相机安装角转换参数产生额外的增量dφC、dωC、dκC。在一条航线内,这些增量可视为常量,依靠其在立体模型上表现的上下视差规律,在无地面控制点条件下,通过在光束法平差中增加对dφC、dωC及dκC补偿的措施,无地面控制点目标定位改善到11～22m左右。     

区域生长的半全局密集匹配算法

针对传统的半全局匹配算法在处理视差变化大、遮挡严重的城市航空影像时,存在匹配精度下降、匹配效率低下的问题,提出了一种基于区域生长的半全局密集匹配方法。采用区域生长算法获取影像的初始视差,并从初始匹配点中挑选可靠的点作为视差控制点;利用区域生长获取的视差图,限制各个方向动态规划的过程以加速最优路径的搜索;通过视差控制点对动态规划的路径进行修正,避免错误匹配代价的传播。基于城区无人机影像的实验结果表明,所提算法不仅可以提高匹配结果正确率,还能使耗费的内存和时间都不到原算法的50%。     

平面约束条件在LIDAR点云滤波中的应用

介绍了一种利用平面约束条件对LIDAR点云数据进行滤波的方法,利用每个数据点的邻域点拟合平面,根据平面约束条件和平面点分类方法得到地面点,最后利用地面点内插该区域的DTM.     

热红外遥感反演陆地表面温度研究进展

 总结了地表绝对发射率信息的提取方法； 综述了热红外遥感反演陆面温度的各种方法，并指出这些方法的优缺点、适用性及应用情况； 分析了热红外遥感反演陆面温度面临的困难； 展望了热红外遥感反演陆面温度的发展趋势。     

一种POS数据辅助多视角倾斜航空影像匹配方法

提出一种利用POS辅助多视角倾斜影像匹配的算法。首先,利用POS数据对倾斜影像进行近似核线纠正;然后,用SIFTGPU算法对纠正影像进行特征匹配,根据匹配结果计算出两张影像的水平和垂直方向视差进而求得其近似重叠区域;将重叠区域进行分块特征匹配,采用比值提纯法、视差约束和RANSAC算法等约束条件剔除误匹配;最后,将匹配结果通过POS数据反算回到原始影像上。试验结果表明,将POS数据应用到多视角倾斜影像匹配中,可快速获得比常规影像匹配方法数量更多、分布更均匀的匹配点。     

遥感影像纠正中GCP选取及自动化实现

地面控制点的选取是遥感影像几何纠正中的重要环节。控制点的数量、分布和精度直接影响影像纠正的精度和质量。本文较为系统地总结了控制点选取的诸多要素及注意事项,并对GCP选取的自动化技术进行了探索和实践。     

航空三线阵CCD影像测制城市数字正射影像

提出了利用三线阵ＣＣＤ相机测制城市数字正射影像和建立三维模型与目标,开展航空直接获取数字影像的摄影测量。着重讨论了利用三线阵ＣＣＤ影像计算自由外方位无素并生成模型ＤＥＭ然后利用少量控制点建立地面－模型坐标转换关系,生成地面坐标系的ＤＥＭ和正射影像。     

基于RFM的高分辨率卫星遥感影像自动匹配研究

摘　要：提出一种基于有理多项式模型（RFM）进行高分辨率卫星遥感影像自动匹配的方法。首先利用RFM进行高分辨率卫星影像直接定位和同名点预测;然后基于投影轨迹建立近似核线方程,并分析了核线精度;接着采用金字塔影像策略进行核线约束的近似一维影像匹配,并经最小二乘影像匹配精化匹配结果;最后采用RANSAC算法剔除误匹配点以获取最终的匹配结果。通过与二维灰度相关方法和SIFT匹配方法的比较试验,证明本文方法可靠性好、匹配成功率高,较好地解决了多时相、大姿态角高分辨率卫星遥感影像的自动匹配难题。     

GROUND CONTROL DETERMINATION FOR REGISTRATION OF SATELLITE IMAGERY USING DIGITAL MAP DATA

Work is reported on the production of terrain elevation data from SPOT imagery. An important step in this process is determination of exterior orientation parameters for the images. Although an initial estimate is available in the SPOT header, refinements are required based on plan and height data. These are generally derived from photogrammetric measurements (or sources such as global positioning satellite systems), but accurate manual determination is time consuming. This paper reports an alternative approach by investigating the use of existing map data (located on the earth's surface and in a known projection) to find corresponding “ground control points” in both map and image. Available maps may be in digital or paper form depending on the state of development of mapping in the part of the world being studied. The last revision date and the cartographic generalisation employed will also effect the fidelity of the final result. Practical semi-automatic techniques for determining the height of ground control points from existing map data are described, including multiple profiles through digitised contour data, a commercial terrain modelling package based on Delaunay triangulation and the use of triangulation points on prominent features. Comparisons between the methods are made and results obtained are compared with Institut Géographique National datasets and photogrammetric measurements. Methods for fully automating not only the height determination but also the location of ground control features within a map database are discussed. Map and image registration is described and illustrated using Laser-Scan's Rover software. Interactive and automated methods of registration are discussed.     

基于相对定向结果和多视几何约束的序列影像直线相关研究

以对序列影像进行连续像对相对定向的结果 (自由网相机参数和部分同名像点 )为基础 ,对VIDEO序列影像的直线相关问题进行了研究 ,提出并实现了相关的算法 ,给出了在具体实践中的应用效果。     

多尺度区域生长点云滤波地表拟合法

针对经典的迭代三角网加密算法(PTD)过度侵蚀地形、误差累积的问题,提出了一种基于区域生长的多尺度滤波方法。该方法引入了金字塔策略建立不同层次的点云结构,以上层种子点为基准对下层种子点进行处理:先通过不规则三角网滤除非地面点,然后依据局部地形设置动态阈值,以表面拟合区域生长算法增长受侵蚀的地面种子点,循环迭代逐渐逼近真实地面。通过对ISPRS提供的15个基准数据集进行测试,第Ⅰ、Ⅱ类误差以及总误差分别为2.40%、3.67%、2.84%,Kappa系数为93.74%。结果表明,该算法具有更强的性能,可以获得理想的地面模型。