CN102735216B - CCD stereoscopic camera three-line imagery data adjustment processing method - Google Patents

CCD stereoscopic camera three-line imagery data adjustment processing method Download PDF

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CN102735216B
CN102735216B CN201110087467.0A CN201110087467A CN102735216B CN 102735216 B CN102735216 B CN 102735216B CN 201110087467 A CN201110087467 A CN 201110087467A CN 102735216 B CN102735216 B CN 102735216B
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CN102735216A (en
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李春来
任鑫
刘建军
牟伶俐
邹小端
王文睿
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National Astronomical Observatories of CAS
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Abstract

本发明公开了一种CCD立体相机三线阵影像数据平差处理方法,该方法包括步骤:步骤1,获取月面图像数据以及对应的星历数据和姿态数据;步骤2,利用图像自动匹配技术提取同一轨不同视角的图像数据以及相邻轨道图像数据的同名像点;步骤3,利用上述数据以及同名像点,采用独立模型法区域网平差进行测区平差处理;步骤4,在测区平差的基础上进行全月球平差处理。本发明的方法在平差处理中不需要解算外方位元素和加密点的坐标,在保证数据处理精度的前提下明显简化了平差处理过程。

The invention discloses a three-line image data adjustment processing method of a CCD stereo camera. The method comprises the following steps: step 1, obtaining lunar surface image data and corresponding ephemeris data and attitude data; step 2, using image automatic matching technology to extract The image data of the same track with different viewing angles and the image points of the same name of the adjacent track image data; step 3, use the above data and the image points of the same name, and use the independent model method block adjustment to perform the survey area adjustment process; step 4, in the survey area The full moon adjustment is performed on the basis of the adjustment. The method of the invention does not need to calculate the coordinates of the outer orientation elements and encrypted points in the adjustment processing, and obviously simplifies the adjustment processing process on the premise of ensuring the accuracy of data processing.

Description

CCD立体相机三线阵影像数据平差处理方法Adjustment processing method for three-line array image data of CCD stereo camera

技术领域 technical field

本发明涉及图像处理方法及应用领域,特别是涉及一种适用于月球CCD立体相机三线阵影像数据的平差处理方法。The invention relates to image processing methods and application fields, in particular to an adjustment processing method suitable for three-line array image data of a lunar CCD stereo camera.

背景技术 Background technique

CCD立体相机是一台只有一组光学镜头、探测器大小为1024×1024的面阵相机,在面阵上读取沿垂直于飞行方向上的第11行、第512行和第1013行,分别作为前视、正视和后视三个不同视角的影像阵列,每行线阵的像元数为512列,前视、正视和后视相邻线阵之间视角差均为16.7°,成像谱段为0.5μm~0.75μm的可见光波段。根据卫星预定的在轨飞行参数,相机的扫描速度设为11.89帧/秒,以保证卫星在200km高的轨道上三条线阵同时向前、向下和向后三个方向以推扫方式获取的三幅二维影像条带都能对卫星飞过的月面进行100%成像。三条影像条带几乎是同时获取的,幅宽为60km,在卫星飞行方向具有100%的重叠,在赤道附近相邻轨道影像条带的重叠度约为41%,高纬度地区重叠度更大,为月表三维地形几何重建提供了足够的影像信息。图2给出CCD立体相机图像数据获取的过程。The CCD stereo camera is an area array camera with only one set of optical lenses and a detector size of 1024×1024. On the area array, the 11th, 512th and 1013th lines perpendicular to the flight direction are read, respectively. As an image array with three different viewing angles of front view, front view and rear view, the number of pixels in each line array is 512 columns, and the viewing angle difference between adjacent line arrays of front view, front view and rear view is 16.7°. The segment is the visible light band of 0.5 μm to 0.75 μm. According to the on-orbit flight parameters predetermined by the satellite, the scanning speed of the camera is set to 11.89 frames per second to ensure that the three linear arrays of the satellite are acquired by push-broom in the three directions of forward, downward and backward at the same time on the orbit at a height of 200km. The three two-dimensional image strips can all image 100% of the lunar surface that the satellite flies over. The three image strips are acquired almost at the same time, with a width of 60km and 100% overlap in the direction of satellite flight. The overlap of adjacent orbit image strips near the equator is about 41%, and the overlap is greater in high latitudes. It provides enough image information for the three-dimensional terrain geometry reconstruction of the lunar surface. Figure 2 shows the process of CCD stereo camera image data acquisition.

CCD立体相机三线阵影像数据平差处理的主要目的是实现卫星在不同时间、不同位置等获取的影像数据在全月范围内的无缝镶嵌和绝对定向,根据卫星摄影测量原理,平差处理的首要任务是解算三线阵影像数据每条线阵的外方位元素(即获取该线阵影像时刻卫星的空间位置和姿态信息)。由于CCD立体相机在同一个扫描周期内只有前视、正视和后视三条影像,受外方位元素变化、地形起伏等的影响,用于计算该条线阵外方位元素的同名像点(至少需要6个),不可能都落在此三条影像上,因此无法从几何上解算该扫描周期的外方位元素,需要用一些简化的算法近似处理。对于卫星摄影而言,平台较平稳,外方位元素变化不大,Hofmann、王任享等人提出采用适当大间距的时刻,即定向时刻或EFP时刻,将航线模型离散化,近似的表达航线模型和外方位元素。The main purpose of the adjustment processing of the three-line array image data of the CCD stereo camera is to realize the seamless mosaic and absolute orientation of the image data acquired by the satellite at different times and different positions within the whole month. According to the principle of satellite photogrammetry, the adjustment processing The first task is to calculate the outer orientation elements of each line array of the three line array image data (that is, to obtain the spatial position and attitude information of the satellite at the moment of the line array image). Since the CCD stereo camera has only three images of front view, front view and rear view in the same scanning cycle, affected by changes in the outer orientation elements, terrain fluctuations, etc., it is used to calculate the same-named image points of the outer orientation elements of the line array (at least 6), it is impossible to fall on these three images, so it is impossible to geometrically solve the outer azimuth elements of this scanning period, and some simplified algorithms need to be used for approximate processing. For satellite photography, the platform is relatively stable, and the outer orientation elements do not change much. Hofmann, Wang Renxiang and others proposed to use the time with a large distance between them, that is, the orientation time or EFP time, to discretize the route model, and approximate the expression of the route model and the outer position. Orientation element.

上世纪80年代,德国学者Hofmann等人首次在MOMS项目中创立了处理三线阵CCD影像的光束法平差方法,即“定向影像法”。该方法将仅仅依靠三线阵影像本身无法解算CCD影像每一个采样周期(时刻)的外方位元素问题化解为只解算“定向影像”时刻的外方位元素,而任意CCD影像采样时刻的外方位元素则从其相邻的定向影像值中内插得到。因此平差计算只需要解算这些定向影像的外方位元素,从而减少了外方位元素的数量和计算量。In the 1980s, German scholar Hofmann and others first created the beam adjustment method for processing three-line array CCD images in the MOMS project, that is, the "directional image method". This method solves the problem that the outer orientation elements of each sampling cycle (moment) of the CCD image cannot be solved only by the three-line array image itself, and only solves the outer orientation elements of the "directional image" moment, while the outer orientation element of any CCD image sampling moment Elements are interpolated from their adjacent oriented image values. Therefore, the adjustment calculation only needs to solve the exterior orientation elements of these oriented images, thereby reducing the number of exterior orientation elements and the amount of calculation.

等效像片法是王任享等人提出的一种处理方法,该算法把一定时间间隔的一组线阵影像进行变换,生成一个面中心投影的等效影像,然后用面中心投影的算法来处理。这一方法也减少了外方位元素的数量和计算量。The equivalent photo method is a processing method proposed by Wang Renxiang et al. This algorithm transforms a set of linear array images at a certain time interval to generate an equivalent image of the plane center projection, and then uses the plane center projection algorithm to process . This approach also reduces the number of exterior orientation elements and computation.

虽然,定向片法和等效像片法等处理方法明显减少了平差处理中的外方位元素的数量,但是用于解算外方位元素的加密点(同名像点)坐标也是平差处理中待解算的未知数,数量巨大,增加了平差处理的工作量和难度。Although the processing methods such as the oriented slice method and the equivalent photographic method obviously reduce the number of external orientation elements in the adjustment process, the coordinates of the encrypted points (picture points with the same name) used to solve the external orientation elements are also used in the adjustment process. The number of unknowns to be solved is huge, which increases the workload and difficulty of adjustment processing.

发明内容 Contents of the invention

本发明的目的在于,通过借鉴定向片法和EFP(等效像片)法等对整条航线影像数据近似处理的方法,采用独立模型法区域网空中三角测量的理论与方法,提出了一种针对CCD立体相机月球三线阵影像数据进行平差处理的方法,克服了无法从几何上解算CCD立体相机三线阵影像每一条扫描线外方位元素的难题。The purpose of the present invention is to, by referring to the methods of approximate processing of the entire route image data such as the directional film method and the EFP (equivalent photo) method, and adopting the theory and method of the independent model method area network aerial triangulation, a kind of method is proposed. The method of adjusting the lunar three-line array image data of the CCD stereo camera overcomes the problem that the azimuth elements outside each scanning line of the three-line array image of the CCD stereo camera cannot be solved geometrically.

本发明的CCD立体相机三线阵影像数据平差处理方法包括步骤:步骤1,获取月面图像数据以及对应的星历数据和姿态数据;步骤2,利用图像自动匹配技术提取同一轨不同视角的图像数据以及相邻轨道图像数据的同名像点;步骤3,利用上述数据以及同名像点,采用独立模型法区域网平差进行测区平差处理;步骤4,在测区平差的基础上进行全月球平差处理。The CCD stereo camera three-line array image data adjustment processing method of the present invention comprises the steps: Step 1, obtaining lunar surface image data and corresponding ephemeris data and attitude data; Step 2, utilizing image automatic matching technology to extract images of different viewing angles on the same track Data and image points with the same name of adjacent track image data; step 3, use the above data and image points with the same name, and use the independent model method block adjustment to perform survey area adjustment; step 4, perform survey area adjustment on the basis of survey area adjustment Full lunar adjustment processing.

优选地,将全月球表面分为多个制图区,每个制图区再划分为多个测区,每个测区有若干航带影像。Preferably, the entire lunar surface is divided into multiple mapping areas, and each mapping area is further divided into multiple survey areas, and each survey area has several aerial images.

优选地,所述不同视角包括前视、正视和后视。Preferably, the different viewing angles include front view, front view and rear view.

优选地,匹配算法采用尺度不变特征变换SIFT特征匹配和最小二乘匹配相结合的方式。Preferably, the matching algorithm adopts a combination of scale invariant feature transformation SIFT feature matching and least square matching.

优选地,采用SIFT特征匹配算法提供特征的初始位置,再采用最小二乘匹配实现图像精匹配。Preferably, the SIFT feature matching algorithm is used to provide the initial position of the feature, and then the least squares matching is used to achieve precise image matching.

优选地,所述独立模型通过以下方式构建:在测区范围内得到正视影像上的定向片序列,前视与正视、正视与后视、前视与后视上的同名定向片组成定向片对,每个定向片对经过相对定向处理构建独立模型,该独立模型是独立模型法区域网平差的最小单元。Preferably, the independent model is constructed in the following manner: within the scope of the measurement area, the sequence of directional slices on the front view image is obtained, and the directional slices with the same name on the front view and the front view, the front view and the back view, and the front view and the back view form an directional slice pair , each pair of oriented slices undergoes relative orientation processing to construct an independent model, which is the smallest unit of the block adjustment of the independent model method.

本发明的方法在平差处理中不需要解算外方位元素和加密点的坐标,而是解算另外一组参数(相对定向参数和绝对定向参数),用于三线阵影像数据在全月范围内的无缝镶嵌和绝对定向,待解算的未知数的个数明显少于现有技术中的上述两种方法,明显简化了平差处理过程,但是数据处理精度并未降低。The method of the present invention does not need to solve the coordinates of the outer azimuth elements and encrypted points in the adjustment process, but solves another set of parameters (relative orientation parameters and absolute orientation parameters), which are used for the three-line array image data in the whole month range The seamless mosaic and absolute orientation in the interior, the number of unknowns to be solved is obviously less than the above two methods in the prior art, which obviously simplifies the adjustment process, but the data processing accuracy does not decrease.

附图说明 Description of drawings

图1为测区平差算法和全球平差算法的处理流程图;Fig. 1 is the processing flowchart of the area adjustment algorithm and the global adjustment algorithm;

图2为CCD立体相机月表三线阵影像数据获取过程示意图;Fig. 2 is a schematic diagram of the acquisition process of the three-line array image data of the lunar surface of the CCD stereo camera;

图3为CCD立体相机正视影像上定向片划分示意图;Fig. 3 is a schematic diagram of the division of directional slices on the front view image of the CCD stereo camera;

图4a和4b为独立模型线性误差改正前后结果比较示意图;Figures 4a and 4b are schematic diagrams of the comparison of the results before and after the linear error correction of the independent model;

图5a和5b为CCD立体相机平差处理测区划分空间分布示意图;Figures 5a and 5b are schematic diagrams of the spatial distribution of the CCD stereo camera adjustment processing measuring area division;

图6a和6b为测区平差和全球平差月面控制点空间分布示意图;Figures 6a and 6b are schematic diagrams of the spatial distribution of lunar surface control points for survey area adjustment and global adjustment;

图6c为图6b的局部放大图。Fig. 6c is a partially enlarged view of Fig. 6b.

具体实施方式 detailed description

为使本发明的目的、技术方案和优点更加清楚明白,以下结合具体实施例,并参照附图,对本发明进一步详细说明。In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be described in further detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

参照图1的流程图,详细描述了本发明的月球CCD立体相机三线阵影像数据的平差处理方法。本发明的平差处理方法所依赖的前提条件是卫星摄影平台较平稳,外方位元素变化不大的特点。Referring to the flow chart of Fig. 1, the adjustment processing method of the three-line array image data of the lunar CCD stereo camera of the present invention is described in detail. The precondition that the adjustment processing method of the present invention relies on is that the satellite photography platform is relatively stable, and the external azimuth elements do not change much.

参照图1,在执行该平差处理方法时,首先进行数据准备与组织。Referring to Fig. 1, when implementing the adjustment processing method, data preparation and organization are performed first.

其中以CE-1(嫦娥一号)为例,卫星在其寿命期间共获得1000多轨图像数据,从其中选择了628(该数据仅是示例性的,可根据实际情况选择任意合适的数量)轨色调均一与光照条件差异小等图像质量较好的、覆盖全月面的图像数据。另外,为了进行平差处理还必须准备图像数据对应的卫星星历数据和姿态数据,卫星星历数据是测控部门根据地面观测对CE-1卫星进行跟踪测量得到的卫星位置数据,姿态是由卫星上携带的仪器设备测量得到的卫星平台滚动、俯仰、偏航等数据。Taking CE-1 (Chang'e No. 1) as an example, the satellite obtained 1,000 multi-track image data during its lifetime, and selected 628 of them (this data is only exemplary, and any suitable number can be selected according to the actual situation) Image data with better image quality, such as uniform track tone and small difference in lighting conditions, covering the entire lunar surface. In addition, satellite ephemeris data and attitude data corresponding to the image data must be prepared for adjustment processing. The satellite ephemeris data is the satellite position data obtained by the measurement and control department from tracking and measuring the CE-1 satellite based on ground observations. The attitude is determined by the satellite The satellite platform roll, pitch, yaw and other data measured by the equipment carried on board.

为了保证平差结果在全球范围内的一致性,必须实现上述选取的图像数据在全球范围内的无缝镶嵌和绝对定向,在全月范围内进行平差处理。为了进行全球平差处理,将全球划分为若干测区,先进行测区平差处理,再进行全球平差处理。In order to ensure the consistency of the adjustment results on a global scale, it is necessary to realize the seamless mosaic and absolute orientation of the above-mentioned selected image data on a global scale, and carry out the adjustment processing on a full-month scale. In order to carry out the global adjustment processing, the whole world is divided into several survey areas, the survey area adjustment process is performed first, and then the global adjustment process is performed.

将全月球表面分为若干制图区,例如,分为S70°-N70°,S70°-S90°和N70°-N90°这三个制图区,每个制图区再划分为若干测区,全球共202测区,每个测区大约20条航带影像。为了保证测区之间的连接条件,裁剪数据时相邻测区在沿经度方向重叠约4°,沿纬度方向重叠约2°。Divide the entire lunar surface into several mapping areas, for example, three mapping areas of S70°-N70°, S70°-S90° and N70°-N90°, and each mapping area is further divided into several surveying areas. 202 survey areas, about 20 aerial images for each survey area. In order to ensure the connection conditions between survey areas, adjacent survey areas overlap about 4° along the longitude direction and about 2° along the latitude direction when clipping the data.

测区划分结果参见图4a和4b。图4a为S70°-N70°中低纬度制图区测区划分示意图,共有170个测区,纬度跨度范围为14°,共10个纬度带,经度跨度范围随着纬度不同而不同;图4b为S70°-S90°和N70°-N90°极区制图区测区划分示意图,共有32个测区。图中给出了每个测区的编号信息。See Figures 4a and 4b for the division results of the survey area. Figure 4a is a schematic diagram of the survey area division of the S70°-N70° middle and low latitude mapping area. There are 170 survey areas in total, with a latitude span of 14° and a total of 10 latitude zones. The longitude span varies with different latitudes; Figure 4b is S70°-S90° and N70°-N90° polar mapping area survey area division diagram, a total of 32 survey areas. The number information of each survey area is given in the figure.

在该步骤中,将所获取的月面图像数据,以及对应的星历数据和姿态数据等按照测区进行裁剪并按照测区编号命名的文件夹管理起来,作为后续图像匹配和平差处理的输入数据。In this step, the acquired lunar surface image data, as well as the corresponding ephemeris data and attitude data, etc. are cut according to the survey area and managed in folders named according to the survey area number, as the input for subsequent image matching and adjustment processing data.

之后,利用上述步骤中获取的月面图像数据,进行三线阵影像自动匹配匹配处理步骤。Afterwards, using the image data of the lunar surface acquired in the above steps, the automatic matching and matching processing steps of the three-line array images are performed.

图像匹配主要是实现每个测区内同轨内前视、正视和后视图像之间,以及相邻轨道图像数据之间重叠区同名像点的提取。Image matching is mainly to realize the extraction of the image points with the same name in the overlapping area between the front-sight, front-sight and back-sight images of the same track in each survey area, as well as between adjacent track image data.

匹配算法采用SIFT(ScaleInvariantFeatureTransform)特征匹配和最小二乘匹配相结合的方式。基于SIFT描述符的特征匹配因具有对影像尺度、亮度、对比度、旋转、平移、微小仿射的不变性,已被成功地应用到了很多领域,是目前最佳的特征描述符。SIFT特征匹配不仅对图像的尺度变化和旋转具有不变性,对光照的变化和图像变形具有较强的适应性,而且在计算过程中主要利用了DOG差分算子,找到的特征大部分是“blobs”(圆状点),这恰好适合月球影像纹理贫乏,具有较多微小撞击坑的圆状点这一特征。其中CCD图像空间分辨率为120m,对于直径在500m以内的撞击坑由于边缘的强反射在图像上表现为亮圆状点。图像精匹配主要是通过最小二乘匹配实现的,最小二乘匹配算法最难解决的问题是初始位置的确定,这里我们采用SIFT特征匹配算法提供特征的初始位置,然后再采用最小二乘匹配,实现图像精匹配。图像匹配精度优于0.3像元,CCD立体相机图像数据的空间分辨率为120m。The matching algorithm adopts the combination of SIFT (ScaleInvariantFeatureTransform) feature matching and least squares matching. Feature matching based on SIFT descriptors has been successfully applied to many fields because of its invariance to image scale, brightness, contrast, rotation, translation, and small affine, and it is currently the best feature descriptor. SIFT feature matching is not only invariant to the scale change and rotation of the image, but also has strong adaptability to the change of illumination and image deformation, and the DOG difference operator is mainly used in the calculation process, and most of the found features are "blobs". "(circular point), which is just suitable for the feature of lunar image with poor texture and many tiny impact craters. The spatial resolution of the CCD image is 120m, and the impact craters with a diameter of less than 500m appear as bright round spots on the image due to the strong reflection at the edge. Image fine matching is mainly realized by least squares matching. The most difficult problem of the least squares matching algorithm is to determine the initial position. Here we use the SIFT feature matching algorithm to provide the initial position of the feature, and then use the least squares matching. Realize image fine matching. The image matching accuracy is better than 0.3 pixel, and the spatial resolution of the CCD stereo camera image data is 120m.

三线阵影像自动匹配包括同轨图像数据(包括前视、正视与后视图像两两之间)和相邻轨道图像数据之间的自动匹配,自动匹配的主要目的是提取用于平差参数(即相对定向参数和绝对定向参数)解算的加密点(或同名像点)的图像坐标。The automatic matching of the three-line array image includes the automatic matching between the image data of the same track (including the front-view, front-view and rear-view images) and the adjacent track image data. The main purpose of the automatic matching is to extract the adjustment parameters ( That is, the image coordinates of the encrypted point (or the image point with the same name) calculated by the relative orientation parameter and the absolute orientation parameter).

根据上述同名像点匹配方法,在同航带、相邻航带、相邻测区的前视、正视和后视影像上选取数量和分布满足相对定向、测区平差、全球平差要求的同名像点,也就是图1中所示的相对定向连接点、绝对定向连接点以及全球平差连接点。然后,在立体环境下对这些同名像点人工检查和修测。这些同名像点是后续测区平差和全球平差处理的输入数据。According to the matching method of image points with the same name above, select the number and distribution of the images that meet the requirements of relative orientation, survey area adjustment, and global adjustment on the front-sight, front-sight and back-sight images of the same flight zone, adjacent flight zone, and adjacent survey area. The image points with the same name are the relative orientation tie points, absolute orientation tie points and global adjustment tie points shown in Figure 1. Then, manually inspect and repair these image points with the same name in a stereoscopic environment. These image points with the same name are the input data for subsequent area adjustment and global adjustment.

在获取上述同名像点之后,进行测区平差处理。After obtaining the above-mentioned image points with the same name, the area adjustment processing is carried out.

参照图1,其中虚线框内的步骤为测区平差处理过程。为了实现三线阵影像数据在全月范围内的无缝镶嵌和绝对定向,将全球划分为若干测区,先进行测区平差处理,再进行全球平差处理。测区平差和全球平差均采用采用独立模型法区域网平差技术。Referring to Figure 1, the steps in the dotted box are the process of area adjustment. In order to realize the seamless mosaic and absolute orientation of the three-line array image data within the whole month, the whole world is divided into several survey areas, and the survey area adjustment processing is performed first, and then the global adjustment processing is performed. Both the area adjustment and the global adjustment adopt the block network adjustment technology using the independent model method.

根据Hofmann、王任享等人提出定向片原理,在测区范围内的正视影像条带上每隔50行选择定向时刻,以定向时刻为中心160行作为定向片宽度,得到正视影像上的定向片序列,前视与后视影像上的定向片边界通过图像匹配确定。前视与正视、正视与后视、前视与后视上的同名定向片组成定向片对,每个定向片对经过相对定向处理构建独立模型。According to the principle of directional slice proposed by Hofmann, Wang Renxiang, etc., the directional time is selected every 50 lines on the orthoscopic image strip within the survey area, and 160 lines are taken as the width of the directional slice with the oriented time as the center, and the directional slice sequence on the orthoscopic image is obtained. , the orientation slice boundaries on the front-view and back-view images are determined by image matching. Orientation slices with the same name on front view and front view, front view and back view, front view and back view form an orientation slice pair, and each orientation slice pair undergoes relative orientation processing to build an independent model.

图3为CCD立体相机正视影像上定向片划分示意图。图中横方向代表CCD立体相机正视影像条带的高度,高度为512像素,长度与实际的影像扫描行数一致。黑色实线为独立模型中心线(图中在左侧用虚线已经标注),该中心线对应的线阵数据获取时刻即为该模型定向时刻,相邻中心线间距为50行。独立模型的高度与影像条带的高度一致,即512像素,以独立模型中心线为中心,模型宽度为160行。符号代表同名像点在定向片上的位置,由图像匹配产生。该独立模型是独立模型法区域网平差的最小单元,测区平差的目的就是将定向片对构建的独立模型在测区范围内无缝的连接起来,形成整个测区的地面立体模型。Fig. 3 is a schematic diagram of the division of directional slices on the front view image of the CCD stereo camera. The horizontal direction in the figure represents the height of the front view image strip of the CCD stereo camera, the height is 512 pixels, and the length is consistent with the actual number of image scanning lines. The black solid line is the center line of the independent model (marked with a dotted line on the left in the figure), and the line array data acquisition time corresponding to the center line is the orientation time of the model, and the distance between adjacent center lines is 50 lines. The height of the independent model is consistent with the height of the image strip, that is, 512 pixels, centered on the center line of the independent model, and the width of the model is 160 lines. symbol Represents the position of the image point with the same name on the orientation sheet, which is generated by image matching. The independent model is the smallest unit of the block adjustment of the independent model method. The purpose of the survey area adjustment is to seamlessly connect the independent models constructed by the directional patch pairs within the survey area to form a ground three-dimensional model of the entire survey area.

测区平差处理过程分以下几步完成:The survey area adjustment process is completed in the following steps:

(1)定向片内定向:(1) Orientation on-chip orientation:

将同名像点的图像坐标转换成以定向片像主点为坐标原点的像平面坐标。变换公式如下所示:Convert the image coordinates of the image point with the same name into the image plane coordinates with the principal point of the oriented image as the coordinate origin. The transformation formula is as follows:

xx ′′ == (( dd xx -- xx 00 ++ LL 00 )) ·· dsds ythe y ′′ == (( ythe y -- ythe y 00 )) ·· dsds dd xx == xx -- LL ii -- -- -- (( 11 ))

其中,x′、y′是像平面坐标值(单位为mm),dx为定向片中x方向的图像坐标值(单位为像素);x、y为原始图像行、列号;ds=14μm为探测器像元大小;x0=0.8050,y0=-0.7990为像主点的像平面坐标值(单位为像素);L0为扫描线在CCD面阵中的位置(前视L0=11;正视L0=512,后视L0=1013);Li为定向片中心扫描行在影像条带中的行号。Wherein, x ', y ' are image plane coordinate values (unit is mm), and d x is the image coordinate value (unit is pixel) of x direction in the orientation sheet; x, y are original image row, column number; ds=14 μ m Be the detector pixel size; x 0 =0.8050, y 0 =-0.7990 is the image plane coordinate value (unit is pixel) of the principal point; L 0 is the position of the scanning line in the CCD array (front-sight L 0 = 11; front view L 0 =512, back view L 0 =1013); L i is the line number of the center scanning line of the directional slice in the image strip.

通过像片内定向处理,将原始同名像点图像坐标值转换为以像主点为坐标原点的像平面坐标值,该坐标值将作为模型相对定向处理的输入数据。Through the orientation processing in the photo, the image coordinates of the original image point with the same name are converted into the image plane coordinates with the principal point of the image as the coordinate origin, and the coordinates will be used as the input data for the relative orientation processing of the model.

(2)相对定向处理:利用定向片对的同名像点坐标,通过共面条件建立误差方程,解求定向片的相对定向元素。共面条件满足的方程如下:(2) Relative orientation processing: using the coordinates of the same-named image point of the orientation slice pair, the error equation is established through the coplanar condition, and the relative orientation elements of the orientation slice are solved. The equations that satisfy the coplanar condition are as follows:

其中,κ,ω′,κ′为待求的相对定向元素;B为基线长度,前视与正视或正视与后视模型B=60km,前视与后视模型B=120km;u,v,w为左像点的左像空间坐标,u′,v′,w′为右像点的右像空间坐标,由左右定向片的同名像点像平面坐标通过其旋转矩阵坐标转换得到,旋转矩阵由定向片的外方位角元素构建。in, kappa, ω', κ' are the relative orientation elements to be found; B is the baseline length, the front-sight and front-sight or front-sight and rear-sight model B=60km, the front-sight and rear-sight model B=120km; u, v, w are the left image The left image space coordinates of the point, u′, v′, w′ are the right image space coordinates of the right image point, which are obtained from the image plane coordinates of the image point with the same name on the left and right directional slices through their rotation matrix coordinate conversion, and the rotation matrix is obtained by the directional slice’s Outer azimuth element construction.

上式(式(2))用泰勒级数展开并取一次项得到误差方程式:The above formula (Formula (2)) is expanded by Taylor series and the first-order term is taken to obtain the error equation:

其中,vr为共面条件方程在同名像点处的残差;Among them, v r is the residual error of the coplanar condition equation at the image point with the same name;

为引入相对定向元素近似值计算出的初值;Δω′,Δκ,Δκ′为相对定向元素近似值的改正数,即待解算的未知数的改正数;(x,y),(x′,y′)为左右像点的图像坐标,根据式(1)计算得到;f为相机的焦距长度。 The initial value computed for introducing relative orientation element approximations; Δω′, Δκ, Δκ′ are the correction numbers of the approximate values of the relative orientation elements, that is, the correction numbers of the unknowns to be solved; (x, y), (x′, y′) are the image coordinates of the left and right image points, according to the formula ( 1) Calculated; f is the focal length of the camera.

考虑到定向片是一种近似处理,误差方程式只取用了泰勒展开的一次项式。为了提高解算精度,每个独立模型上选择了约150个均匀分布的定向点,定向点是通过图像匹配得到的同名像点,将这些像点的图像坐标作为观测数,根据方程(3)构建误差方程,根据最小二乘理论构建法方程,解算相对定向参数的增量值Δκ,Δω′,Δκ′,相对定向元素的初始值加上对应的增量值作为相对定向元素值。该处理过程需要进行迭代运算,直到满足精度要求才终止。Considering that the directional slice is an approximate process, the error equation only uses the first-degree term of Taylor expansion. In order to improve the calculation accuracy, about 150 uniformly distributed orientation points are selected on each independent model. The orientation points are image points with the same name obtained through image matching, and the image coordinates of these image points are taken as observation numbers. According to equation (3) Construct the error equation, construct the normal equation according to the least square theory, and solve the incremental value of the relative orientation parameter Δκ, Δω′, Δκ′, the initial value of the relative orientation element plus the corresponding incremental value as the value of the relative orientation element. This process requires iterative operations until the precision requirements are met.

通过相对定向处理,得到独立模型的相对定向元素,用于解算定向点的模型坐标。Through the relative orientation processing, the relative orientation elements of the independent model are obtained, which are used to calculate the model coordinates of the orientation point.

(3)模型坐标计算。(3) Model coordinate calculation.

在相对定向以后,用于构建独立模型的左右像对的旋转矩阵R,R′和基线长度B均为已知,此时左右像片上的同名像点对应的同名光束对相交,交点位置即为同名像点在该独立模型表面上对应的模型点了。根据相对定向元素和设定的基线长可以计算出模型点在模型坐标系下的坐标值,计算公式如:After the relative orientation, the rotation matrices R, R′ and baseline length B of the left and right image pairs used to construct the independent model are known. At this time, the same-named beam pairs corresponding to the same-named image points on the left and right images intersect, and the position of the intersection point is The image point with the same name corresponds to the model point on the surface of the independent model. The coordinate value of the model point in the model coordinate system can be calculated according to the relative orientation element and the set baseline length. The calculation formula is as follows:

U=Us+Mut,V=Vs+Mvt,W=Ws-Mf(4)U=U s +Mu t , V=V s +Mv t , W=W s -Mf(4)

uu tt == -- ff aa 11 xx ++ aa 22 ythe y -- aa 33 ff cc 11 xx ++ cc 22 ythe y -- cc 33 ff vv tt == -- ff bb 11 xx ++ bb 22 ythe y -- bb 33 ff cc 11 xx ++ cc 22 ythe y -- cc 33 ff uu ′′ tt == -- ff aa 11 ′′ xx ++ aa 22 ′′ ythe y -- aa 33 ′′ ff cc 11 ′′ xx ++ cc 22 ′′ ythe y -- cc 33 ′′ ff

Mm == BB uu tt -- uu tt ′′

其中,Us,Vs,Wg为左像片投影中心在模型坐标下的坐标值;U,V,W为模型点在模型坐标下的坐标值;ai,bi,ci和a′i,b′i,c′i(i=1,2,3)分别为左右像片旋转矩阵R,R′的9个矩阵元素;(x,y),(x′,y′)为左右像点的图像坐标;f为相机的焦距长度;ut,vt,u′t和M是为了简化公式的表达而构建的中间变量。Among them, U s , V s , W g are the coordinate values of the projection center of the left photo in the model coordinates; U, V, W are the coordinate values of the model points in the model coordinates; a i , b i , c i and a ′ i , b′ i , c′ i (i=1, 2, 3) are the 9 matrix elements of the left and right image rotation matrices R and R′ respectively; (x, y), (x′, y′) are The image coordinates of the left and right image points; f is the focal length of the camera; u t , v t , u′ t and M are intermediate variables constructed to simplify the expression of the formula.

通过模型坐标计算,我们得到每个模型点的模型坐标值,将作为绝对定向处理的输入数据。Through model coordinate calculation, we get the model coordinate value of each model point, which will be used as input data for absolute orientation processing.

(4)模型坐标改正。(4) Model coordinate correction.

实验结果表明,独立模型在X方向存在明显的系统误差,此种误差在X方向是线性变化的。为解决这个问题,在平差算法中加入了X方向的线性误差改正,误差改正前后的结果见图4a和4b。图中曲面A和曲面B是用一个独立模型上均匀分布的模型点在像空间坐标系下的三维坐标构建的。图4a是模型未进行线性误差改正的平差结果,在X方向存在明显的线性变化;图4b是经过线性误差改正后的平差结果,系统误差明显消除。坐标改正方程如下:The experimental results show that the independent model has obvious systematic errors in the X direction, and this error changes linearly in the X direction. To solve this problem, linear error correction in the X direction is added to the adjustment algorithm. The results before and after error correction are shown in Figures 4a and 4b. Surface A and surface B in the figure are constructed using the three-dimensional coordinates of uniformly distributed model points on an independent model in the image space coordinate system. Figure 4a is the adjustment result of the model without linear error correction, and there is an obvious linear change in the X direction; Figure 4b is the adjustment result after linear error correction, and the systematic error is obviously eliminated. The coordinate correction equation is as follows:

U′=U+aU(5)U'=U+aU(5)

其中,U为模型X坐标。a为坐标改正系数。Among them, U is the X coordinate of the model. a is the coordinate correction coefficient.

绝对定向处理将用改正后的模型坐标作为输入。The absolute orientation process will use the corrected model coordinates as input.

(5)引入激光高度计数据作为高程控制信息。(5) Introduce laser altimeter data as elevation control information.

在区域网平差处理过程中,控制点的高程信息是从空间分辨率为3公里的DEM数据上获取的,该DEM数据是利用嫦娥一号探测器激光高度计的探测数据制作的。高程控制点误差方程如下:During the process of block adjustment, the elevation information of the control points is obtained from the DEM data with a spatial resolution of 3 kilometers, which is made by using the detection data of the laser altimeter of the Chang'e-1 probe. The height control point error equation is as follows:

vv ii == ZZ ii -- ZZ ii demdem -- -- -- (( 66 ))

ZZ ii demdem == aa 00 ++ aa 11 Xx ii ++ aa 22 YY ii ++ aa 33 Xx ii 22 ++ aa 44 Xx ii YY ii ++ aa 55 YY ii 22

式中,νi为同名像点待解算的Zi坐标与DEM数据上获取的坐标的差值。(Xi,Yi,Zi)是利用前方交会得到的同名像点月面坐标,根据(Xi,Yi,Zi)对应的月面经纬度坐标在DEM数据上获取值。a0,a1,a2,a3,a4,a5为二次曲面系数,该曲面是根据(Xi,Yi,Zi)在DEM上所在的位置附近的3×3格网内的DEM数据建立的。i为高程控制点的编号。In the formula, νi is the Z i coordinate to be solved for the image point with the same name and the Z i coordinate obtained from the DEM data difference in coordinates. (X i , Y i , Z i ) are the lunar surface coordinates of the image point with the same name obtained by forward intersection, and obtained from the DEM data according to the lunar surface latitude and longitude coordinates corresponding to (X i , Y i , Zi ) value. a 0 , a 1 , a 2 , a 3 , a 4 , a 5 are quadric surface coefficients, the surface is a 3×3 grid near the position of (X i , Y i , Zi ) on the DEM built within the DEM data. i is the number of the elevation control point.

在绝对定向处理过程中,该误差方程将作为约束方程参与平差,消除绝对定向结果与参考DEM数据之间的高程系统偏差值,提高绝对定向的精度。In the process of absolute orientation processing, the error equation will be used as a constraint equation to participate in the adjustment, eliminating the elevation system deviation value between the absolute orientation result and the reference DEM data, and improving the accuracy of the absolute orientation.

(6)绝对定向(6) Absolute Orientation

通过以上相对定向过程,我们计算出了左右像片之间的相对位置和姿态(模型坐标系下),但没有换算到像片的绝对位置和姿态,并与有无地面控制点无关。为了求出这些模型点的月面坐标,我们需要将独立模型作为一个整体进行缩放、平移和旋转,并考虑相邻模型之间的连接情况和月面控制点,通过区域网平差,实现独立模型的绝对定向。Through the above relative orientation process, we have calculated the relative position and attitude between the left and right photos (in the model coordinate system), but it has not been converted to the absolute position and attitude of the photo, and has nothing to do with whether there are ground control points. In order to find the lunar surface coordinates of these model points, we need to scale, translate and rotate the independent model as a whole, and consider the connection between adjacent models and the lunar surface control points. The absolute orientation of the model.

模型点经过绝对定向变换,就可以得到月面坐标。变换采用空间相似变换(七参数变换)公式如下:After the model point undergoes absolute orientation transformation, the coordinates of the lunar surface can be obtained. The transformation adopts the spatial similarity transformation (seven parameter transformation) formula as follows:

Xx YY ZZ == λRλR (( ΦΦ ,, ΩΩ ,, KK )) Uu ++ aUu VV WW ++ Xx tt YY tt ZZ tt -- -- -- (( 77 ))

其中,a为线性修正系数;(X,Y,Z)为模型点月面摄影测量坐标;(U,V,W)为模型点的模型坐标;λ为待求的模型比例尺参数,R(Φ,Ω,K)是由旋转角参数构建的旋转矩阵,Φ,Ω,K为3个旋转角参数;Xt,Yt,Zt为3个平移参数。月面摄影测量坐标是以测区中心位置为原点的切面坐标系,根据该原点位置的月固坐标构建切面坐标和月面摄影测量坐标的转换矩阵。Among them, a is the linear correction coefficient; (X, Y, Z) is the lunar surface photogrammetric coordinates of the model point; (U, V, W) is the model coordinate of the model point; λ is the model scale parameter to be obtained, and R(Φ , Ω, K) is a rotation matrix constructed by rotation angle parameters, Φ, Ω, K are three rotation angle parameters; X t , Y t , Z t are three translation parameters. The lunar surface photogrammetric coordinate system is a tangent plane coordinate system with the center of the survey area as the origin, and the conversion matrix between the tangent plane coordinates and the lunar surface photogrammetric coordinates is constructed according to the lunar fixed coordinates of the origin.

将上式用泰勒级数展开并取一次项得到误差方程式:Expand the above formula with Taylor series and take the primary term to get the error equation:

vv Xx == ∂∂ Xx ∂∂ ΦΦ ΔΦΔΦ ++ ∂∂ Xx ∂∂ ΩΩ ΔΩΔΩ ++ ∂∂ Xx ∂∂ KK ΔKΔK ++ ∂∂ Xx ∂∂ Xx tt ΔXΔX tt ++ ∂∂ Xx ∂∂ λλ ΔλΔλ ++ ∂∂ Xx ∂∂ aa ΔaΔa -- (( Xx -- [[ Xx ]] ))

vv YY == ∂∂ Xx ∂∂ ΦΦ ΔΦΔΦ ++ ∂∂ Xx ∂∂ ΩΩ ΔΩΔΩ ++ ∂∂ Xx ∂∂ KK ΔKΔK ++ ∂∂ Xx ∂∂ YY tt ΔYΔY tt ++ ∂∂ Xx ∂∂ λλ ΔλΔλ ++ ∂∂ Xx ∂∂ aa ΔaΔa -- (( YY -- [[ YY ]] )) -- -- -- (( 88 ))

vv ZZ == ∂∂ Xx ∂∂ ΦΦ ΔΦΔΦ ++ ∂∂ Xx ∂∂ ΩΩ ΔΩΔΩ ++ ∂∂ Xx ∂∂ KK ΔKΔK ++ ∂∂ Xx ∂∂ ZZ tt ΔZΔZ tt ++ ∂∂ Xx ∂∂ λλ ΔλΔλ ++ ∂∂ Xx ∂∂ aa ΔaΔa -- (( ZZ -- [[ ZZ ]] ))

式中,vX,vY,vZ为月面坐标的残差,[X],[Y],[Z]为利用未知数的近似值代入式(7)得到的计算结果;Δλ,ΔΦ,ΔΩ,ΔK,ΔXt,ΔYt,ΔZt,Δa为待定值的改正数,即待解算的未知数改正数;为误差方程系数。In the formula, v X , v Y , v Z are the residuals of lunar surface coordinates, [X], [Y], [Z] are the calculation results obtained by substituting approximate values of unknowns into formula (7); Δλ, ΔΦ, ΔΩ , ΔK, ΔX t , ΔY t , ΔZ t , Δa are the correction numbers of the undetermined values, that is, the correction numbers of the unknowns to be solved; is the coefficient of the error equation.

对三线阵数据进行图像匹配,确定一定数量均匀分布的相邻定向片的连接点(即定向片重叠区域的同名像点)后,即可根据式(4)计算出连接点的模型坐标,作为相邻独立模型的连接条件,然后代入误差方程(8),联合方程(6)和(8),采用最小二乘的方法可解算出绝对定向参数Xt,Yt,Zt,Φ,Ω,K,λ和模型坐标改正系数a。连接点的选择要保证航带内(沿卫星飞行方向的影像条带)模型之间,以及相邻航带间模型之间的连接。本工作中,航带内的每个模型均选择了均匀分布的5行(垂直飞行方向)和9列(沿着飞行方向)连接点作为模型连接点,并使相邻模型的重叠区有6列连接点;相邻航带的模型重叠区选择了均匀分布的3列、4行连接点作为航带连接点。After image matching is performed on the three-line array data, and a certain number of evenly distributed connection points of adjacent directional slices are determined (that is, the same-named image points in the overlapping area of directional slices), the model coordinates of the connection points can be calculated according to formula (4), as The connection conditions of the adjacent independent models are then substituted into the error equation (8), joint equations (6) and (8), and the absolute orientation parameters X t , Y t , Z t , Φ, Ω can be solved by using the method of least squares , K, λ and model coordinate correction coefficient a. The selection of connection points should ensure the connection between the models in the flight zone (the image strip along the satellite flight direction) and the connection between the models in the adjacent flight belts. In this work, 5 rows (vertical to the flight direction) and 9 columns (along the flight direction) connection points that are evenly distributed are selected as model connection points for each model in the air strip, and the overlapping area of adjacent models has 6 Column connection points; in the overlapping area of the model of adjacent flight strips, evenly distributed 3-column and 4-row connection points are selected as the connection points of the flight strips.

绝对定向参数Xt,Yt,Zt,Φ,Ω,K,λ和模型坐标改正系数a是解算每个模型点月面坐标的输入参数。Absolute orientation parameters X t , Y t , Z t , Φ, Ω, K, λ and model coordinate correction coefficient a are the input parameters for calculating the lunar surface coordinates of each model point.

(7)月面点坐标计算(7) Moon point coordinate calculation

利用绝对定向元素(Xt,Yt,Zt,Φ,Ω,K,λ)和模型坐标改正系数a,代入方程(7)解算切面坐标值(月面摄影测量坐标)。经过上述绝对定向和全球平差后,我们得到的是在摄影测量坐标系下的坐标值,即以测区中心位置为原点的切面坐标系下的坐标值。根据该位置上的前视与后视定向片组成的独立模型的外方位元素,我们可以建立切面坐标与月固坐标之间的转换矩阵,实现切面坐标到月固坐标的转换,从而求得所有模型点的月面坐标值。Using absolute orientation elements (X t , Y t , Z t , Φ, Ω, K, λ) and model coordinate correction coefficient a, substituting equation (7) to solve the tangent coordinate value (lunar surface photogrammetry coordinates). After the above absolute orientation and global adjustment, what we get is the coordinate value in the photogrammetric coordinate system, that is, the coordinate value in the tangential plane coordinate system with the center of the survey area as the origin. According to the external orientation elements of the independent model composed of the front-sight and rear-sight oriented slices at this position, we can establish the conversion matrix between the tangent plane coordinates and the moon-fixed coordinates, realize the transformation from the tangent plane coordinates to the moon-fixed coordinates, and obtain all The lunar surface coordinate value of the model point.

至此,得到了每个独立测区的每个独立模型的相对定向参数、绝对定向参数,这些参数能够保证测区内所有独立模型的无缝连接,从而实现整个测区的地面立体模型的构建。测区地面模型将作为全球平差处理的独立模型,是全球平差处理的最小单元。So far, the relative orientation parameters and absolute orientation parameters of each independent model in each independent survey area are obtained. These parameters can ensure the seamless connection of all independent models in the survey area, thereby realizing the construction of the ground three-dimensional model of the entire survey area. The surface model of the survey area will be used as an independent model for global adjustment processing, and it is the smallest unit of global adjustment processing.

根据上面的步骤,完成了测区平差处理,之后进行全球平差处理。According to the above steps, the area adjustment processing is completed, and then the global adjustment processing is performed.

测区平差实现了测区内各个独立模型的无缝连接,为了实现全球数据的无缝镶嵌,还必须进行全球平差。将全月球表面按照一定的原则划分成若干区块(或测区,见图5b),在测区平差的基础上,以测区为单元进行全球平差。全球平差也采用上述独立模型法区域网平差的方法,唯一的区别是测区平差的独立模型是由划分的定向片对构建的地面模型,而全球平差的独立模型是整个测区对应的地面模型。测区平差的输入数据是相邻独立模型(由定向片构建)之间的连接点,这些连接点保证了整个测区内数据的无缝镶嵌;全球平差的输入数据是相邻测区之间的连接点,这些连接点保证了所有测区在全球范围内的无缝镶嵌。The survey area adjustment realizes the seamless connection of each independent model in the survey area. In order to realize the seamless mosaic of global data, global adjustment must also be carried out. The entire lunar surface is divided into several blocks (or survey areas, see Figure 5b) according to certain principles, and on the basis of the survey area adjustment, the global adjustment is performed with the survey area as a unit. The global adjustment also adopts the above-mentioned independent model block adjustment method. The only difference is that the independent model of the survey area adjustment is a ground model constructed by dividing directional slice pairs, while the independent model of the global adjustment is the entire survey area corresponding ground model. The input data of the survey area adjustment is the connection points between adjacent independent models (constructed by oriented slices), and these connection points ensure the seamless mosaic of data in the entire survey area; the input data of the global adjustment is the adjacent survey area These connection points ensure a seamless mosaic of all survey areas on a global scale.

测区平差和全球平差均必须在控制点的支持下进行,高程控制点从空间分辨率为3公里的DEM上选择,参见上述式(6)。平面控制点坐标由一定数量和分布的同名像点根据前方交会解算得到。测区平差和全球平差控制点分布参见图6a和6b,图6a为测区平差月面控制点分布图,以编号为E004的测区为例,三角形代表平高(平面与高程)控制点,整个测区均匀地选择了9个,分布在第一轨、中间轨和最后一轨的第一个模型、中间模型和最后一个模型上;圆点代表高程控制点,分布在测区每个地面模型的中心位置;黑色实线代表测区边界线,图中给出了相邻测区的编号信息。图6b为全球平差月面控制点分布图,三角形代表平高控制点,全球均匀的布设了9个;五角星代表高程控制点,全球共202个,分布在每个测区的中心位置;黑色圆点代表相邻测区间的连接点,共约23766个,均匀分布在测区重叠区,图6c为图6b中斜线区域的局部放大图,图中的符号含义与图6b相同。平高控制点的权设定为20.0,高程控制点设定为3.0,高程值从“嫦娥一号CE-1”高度计制作的空间分辨率为3km的全球DEM数据上获取。Both survey area adjustment and global adjustment must be carried out with the support of control points, and the elevation control points are selected from the DEM with a spatial resolution of 3 kilometers, see the above formula (6). The coordinates of the plane control points are calculated from a certain number and distribution of image points with the same name according to the forward intersection solution. See Figure 6a and 6b for the distribution of the control points of the survey area adjustment and the global adjustment. Control points, 9 are evenly selected in the entire survey area, distributed on the first model, middle model and last model of the first track, middle track and last track; dots represent elevation control points, distributed in the survey area The center position of each ground model; the black solid line represents the boundary line of the survey area, and the number information of the adjacent survey area is given in the figure. Figure 6b shows the distribution map of the lunar surface control points of the global adjustment. The triangles represent the height control points, and 9 are evenly arranged around the world; The black dots represent the connection points between adjacent survey intervals, about 23,766 in total, evenly distributed in the overlapping areas of the survey areas. Figure 6c is a partial enlarged view of the oblique area in Figure 6b, and the meanings of the symbols in the figure are the same as those in Figure 6b. The weight of the height control point is set to 20.0, and the height control point is set to 3.0. The elevation value is obtained from the global DEM data with a spatial resolution of 3km produced by the "Chang'e-1 CE-1" altimeter.

利用CCD立体相机内定向参数,测区平差和全球平差处理得到得独立模型的相对定向参数、绝对定向参数,测区绝对定向参数,根据式(1)、式(4)、式(5)、式(7),计算三线阵影像上的任何一个同名像点的月面坐标。另外,测区平差处理中在相邻独立模型重叠区选择了足够数量与分布的连接点,保证了测区内独立模型之间的无缝镶嵌,全球平差处理中在相邻测区的重叠区域也选择了足够数量与分布的连接点,保证了全球范围内相邻测区之间的无缝镶嵌。因此,通过测区平差和全球平差处理,很好的解决了数据的全球连接问题,并为后续数字高程模型和正射影像的制作提供了处理参数。Using the internal orientation parameters of the CCD stereo camera, the survey area adjustment and the global adjustment process, the relative orientation parameters, absolute orientation parameters, and survey area absolute orientation parameters of the independent model are obtained, according to formula (1), formula (4), formula (5 ), Formula (7), calculate the lunar surface coordinates of any image point with the same name on the three-line array image. In addition, in the survey area adjustment process, a sufficient number and distribution of connection points are selected in the overlapping areas of adjacent independent models to ensure the seamless mosaic between independent models in the survey area. A sufficient number and distribution of connection points are also selected for the overlapping area, ensuring seamless mosaic between adjacent survey areas on a global scale. Therefore, the problem of global connection of data is well solved through survey area adjustment and global adjustment, and processing parameters are provided for the subsequent production of digital elevation model and orthophoto.

以上所述的具体实施例,对本发明的目的、技术方案和有益效果进行了进一步详细说明,所应理解的是,以上所述仅为本发明的具体实施例而已,并不用于限制本发明,凡在本发明的精神和原则之内,所做的任何修改、等同替换、改进等,均应包含在本发明的保护范围之内。The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (3)

1.一种CCD立体相机三线阵影像数据平差处理方法,该方法包括步骤:1. A three-line array image data adjustment processing method of a CCD stereo camera, the method comprising steps: 步骤1,获取月面图像数据以及对应的星历数据和姿态数据,在该步骤,将全月球表面分为多个制图区,每个制图区再划分为多个测区,每个测区有若干航带影像;Step 1. Obtain the image data of the lunar surface and the corresponding ephemeris data and attitude data. In this step, the entire lunar surface is divided into multiple mapping areas, and each mapping area is further divided into multiple survey areas. Each survey area has Several air strip images; 步骤2,利用图像自动匹配技术提取同一轨道不同视角的图像数据以及相邻轨道图像数据的同名像点,所述不同视角包括前视、正视和后视,在该步骤,匹配算法采用尺度不变特征变换SIFT特征匹配和最小二乘匹配相结合的方式,采用SIFT特征匹配算法提供特征的初始位置,再采用最小二乘匹配实现图像精匹配;Step 2, use the automatic image matching technology to extract the image data of different viewing angles of the same track and the image points of the same name of the adjacent track image data, the different viewing angles include front view, front view and rear view. In this step, the matching algorithm adopts scale-invariant Feature transformation SIFT feature matching and least squares matching are combined, using SIFT feature matching algorithm to provide the initial position of the feature, and then using least squares matching to achieve image fine matching; 步骤3,利用上述数据以及同名像点,采用独立模型法区域网平差进行测区平差处理;Step 3, using the above-mentioned data and the image points with the same name, use the independent model method block adjustment to carry out survey area adjustment processing; 步骤4,在测区平差的基础上进行全月球平差处理;Step 4, on the basis of the area adjustment, carry out the whole moon adjustment processing; 所述独立模型通过以下方式构建:在测区范围内得到正视影像上的定向片序列,前视与正视、正视与后视、前视与后视上的同名定向片组成定向片对,每个定向片对经过相对定向处理构建独立模型,该独立模型是独立模型法区域网平差的最小单元;The independent model is constructed in the following way: Obtain the sequence of directional slices on the front view image within the scope of the measurement area, and the directional slices with the same name on the front view and the front view, the front view and the back view, the front view and the back view form the directional slice pairs, and each Oriented slice pairs are relatively oriented to construct an independent model, which is the smallest unit of the block adjustment of the independent model method; 步骤3进一步包括步骤:Step 3 further includes the steps of: 将图像坐标转换成以定向片像主点为坐标原点的像平面坐标;Convert the image coordinates into the image plane coordinates with the principal point of the oriented film image as the origin of the coordinates; 利用定向片对的同名像点坐标,通过共面条件建立误差方程,解求定向片的相对定向元素;Using the same-name image point coordinates of the directional slice pair, the error equation is established through the coplanar condition, and the relative directional element of the directional slice is solved; 利用相对定向元素解算该定向片对构建的独立模型上每个同名像点的模型坐标;Use relative orientation elements to solve the model coordinates of each image point with the same name on the independent model constructed by the orientation slice pair; 计算同名像点的月面坐标,Calculate the lunar surface coordinates of the image point with the same name, 其中,将图像坐标转换成以定向片像主点为坐标原点的像平面坐标,变换公式如下:Among them, the image coordinates are converted into image plane coordinates with the principal point of the oriented image as the coordinate origin, and the transformation formula is as follows: xx ′′ == (( dd xx -- xx 00 ++ LL 00 )) ·&Center Dot; dd sthe s ythe y ′′ == (( ythe y -- ythe y 00 )) ·· dd sthe s dd xx == xx -- LL ii -- -- -- (( 11 )) 其中,x′、y′是定向片像平面坐标值,单位为μm;x、y为原始图像坐标值,单位为像素;ds为探测器像元大小;x0、y0为像主点的像平面坐标值,单位为像素,L0为扫描线在CCD面阵中的位置;Li为定向片中心扫描行在影像条带中的行号;dx为定向片的行号,Among them, x', y' are the coordinate values of the oriented image plane, the unit is μm; x, y are the coordinate values of the original image, the unit is pixel; ds is the pixel size of the detector; x 0 , y 0 are the principal points of the image Image plane coordinate value, the unit is pixel, L 0 is the position of the scan line in the CCD array; L i is the line number of the scan line in the image strip in the center of the directional film; d x is the line number of the directional film, 利用定向片对的同名像点坐标,通过共面条件建立误差方程,解求定向片的相对定向元素,共面条件满足的方程如下:Using the coordinates of the same-named image point of the oriented slice pair, the error equation is established through the coplanar condition, and the relative oriented elements of the oriented slice are solved. The equations satisfied by the coplanar condition are as follows: 其中,ω,κ,ω′,κ′为待求的相对定向元素;B为基线长度;u,v,w为左像点的左像空间坐标,u′,v′,w′为右像点的右像空间坐标,由左右定向片的同名像点像平面坐标通过其旋转矩阵坐标转换得到,旋转矩阵由定向片的外方位角元素构建,where, ω, kappa, ω', κ' are the relative orientation elements to be found; B is the baseline length; u, v, w are the left image space coordinates of the left image point, u', v', w' are the right image space coordinates of the right image point , obtained by transforming the image plane coordinates of the same-named image points on the left and right directional slices through their rotation matrix coordinates, and the rotation matrix is constructed by the outer azimuth elements of the directional slices, 式(2)用泰勒级数展开并取一次项得到误差方程式:Equation (2) is expanded by Taylor series and the first-order term is used to obtain the error equation: 式中,f为相机的焦距,In the formula, f is the focal length of the camera, 利用相对定向元素解算该定向片对构建的独立模型上每个同名像点的模型坐标,由下式计算:The model coordinates of each image point with the same name on the independent model constructed by the oriented slice pair are calculated by using the relative oriented elements, which are calculated by the following formula: U=Us+Mut,V=Vs+Mvt,W=Ws-Mf(4)U=U s +Mu t , V=V s +Mv t , W=W s -Mf(4) uu tt == -- ff aa 11 xx ++ aa 22 ythe y -- aa 33 ff cc 11 xx ++ cc 22 ythe y -- cc 33 ff vv tt == -- ff bb 11 xx ++ bb 22 ythe y -- bb 33 ff cc 11 xx ++ cc 22 ythe y -- cc 33 ff uu tt ′′ == -- ff aa 11 ′′ xx ++ aa 22 ′′ ythe y -- aa 33 ′′ ff cc 11 ′′ xx ++ cc 22 ′′ ythe y -- cc 33 ′′ ff Mm == BB uu tt -- uu tt ′′ 其中,Us,Vs,Ws为左定向片投影中心在模型坐标下的坐标值;U,V,W为模型点在模型坐标下的坐标值;ai,bi,ci和a′i,b′i,c′i分别为左右定向片旋转矩阵R,R′的9个矩阵元素,其中i=1,2,3;(x,y),(x′,y′)为左右定向片的像平面坐标值,且(x,y)是根据同名像点在左定向片上的原始图像坐标值代入公式(1)计算得到的结果,(x′,y′)是根据同名像点在右定向片上的原始图像坐标值代入公式(1)计算得到的结果;f为相机的焦距长度;ut,vt,u′t和M是为了简化公式的表达而构建的中间变量。Among them, U s , V s , W s are the coordinate values of the projection center of the left directional sheet under the model coordinates; U, V, W are the coordinate values of the model points under the model coordinates; a i , b i , c i and a ′ i , b′ i , c′ i are the 9 matrix elements of the left and right oriented sheet rotation matrices R, R′ respectively, where i=1, 2, 3; (x, y), (x′, y′) are The image plane coordinates of the left and right oriented slices, and (x, y) is the result obtained by substituting the original image coordinates of the image point with the same name on the left oriented slice into the formula (1), and (x′, y′) is calculated according to the image with the same name Substituting the original image coordinates of the point on the right oriented slice into the result calculated by formula (1); f is the focal length of the camera; u t , v t , u′ t and M are intermediate variables constructed to simplify the expression of the formula. 2.根据权利要求1所述的方法,其特征在于,将全月球表面按照一定的原则划分成若干制图区,每个制图区再划分为多个测区,在测区平差的基础上,以测区为单元进行全球平差。2. method according to claim 1, it is characterized in that, the whole moon surface is divided into some mapping areas according to certain principles, each mapping area is divided into a plurality of surveying areas again, on the basis of surveying area adjustment, The global adjustment is carried out with the survey area as the unit. 3.根据权利要求2所述的方法,其特征在于,所述步骤4进一步包括:3. The method according to claim 2, wherein said step 4 further comprises: 采用图像自动匹配技术,在相邻测区图像数据重叠区域选择一定数量的同名像点作为测区连接点;Using image automatic matching technology, a certain number of image points with the same name are selected in the overlapping area of image data in adjacent survey areas as the connection points of the survey area; 引入激光测月数据进行联合平差,提高控制网的绝对控制精度;Introduce laser lunar survey data for joint adjustment to improve the absolute control accuracy of the control network; 选择用于全球平差处理的控制点数据,并解算测区绝对定向参数。Select the control point data for global adjustment processing, and solve the absolute orientation parameters of the survey area.
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