Toward high-resolution global topography of Mercury from MESSENGER orbital stereo imaging: A prototype model for the H6 (Kuiper) quadrangle
Toward high-resolution global topography of Mercury from MESSENGER orbital stereo imaging: A prototype model for the H6 (Kuiper) quadrangle
复制标题
DOI：
10.1016/j.pss.2017.04.012
复制
发表时间：
2017-08-01
影响因子：
2.4
通讯作者：
Watters, Thomas R.
中科院分区：
文献类型：
--
作者：
Preusker, Frank;Stark, Alexander;Watters, Thomas R.
我们选择了大约10，500个窄角相机（NAC）和广角相机（WAC）图像，这些图像是由信使号的水星双成像系统（MDIS）从轨道上采集的，平均分辨率为150米/像素，用于计算H6（柯伊伯）四边形的数字地形模型（DTM），其从南纬22.5度延伸到北纬22.5度，从东经288.0度延伸到东经360.0度。从这些图像中，我们确定了大约21，100个立体图像组合，每个组合至少包含三个图像。我们应用稀疏多图像匹配来获得代表50，000个地面点的大约250，000个连接点。我们使用的连接点进行摄影测量块调整，这提高了图像指向和地面点位置的三维精度从约850米到约55米。然后，我们应用高密度（逐像素）多图像匹配来获得约450亿个连接点。受益于通过摄影测量块调整实现的改进的图像指向数据，我们计算了约63亿个表面点。通过插值，我们生成了一个DTM的横向间距为221.7米/像素（192像素每度）和垂直精度约30米。将DTM与信使号四年轨道运行中获得的水星激光高度计（MLA）剖面进行比较，发现DTM的几何形状非常坚硬。它可以用作识别MLA离群值的参考（例如，当MLA在其测距极限运行时）或绘制激光高度计轨迹的偏移，这可能是由剩余航天器轨道和姿态误差造成的。经过相关的异常值去除和校正后，MLA剖面与H6的地形剖面非常吻合，均方根高度差仅为88 m。
We selected approximately 10,500 narrow-angle camera (NAC) and wide-angle camera (WAC) images of Mercury acquired from orbit by MESSENGER's Mercury Dual Imaging System (MDIS) with an average resolution of 150 m/pixel to compute a digital terrain model (DTM) for the H6 (Kuiper) quadrangle, which extends from 22.5 degrees S to 22.5 degrees N and from 288.0 degrees E to 360.0 degrees E. From the images, we identified about 21,100 stereo image combinations consisting of at least three images each. We applied sparse multi-image matching to derive approximately 250,000 tie-points representing 50,000 ground points. We used the tie-points to carry out a photogrammetric block adjustment, which improves the image pointing and the accuracy of the ground point positions in three dimensions from about 850 m to approximately 55 m. We then applied high-density (pixel-by-pixel) multi-image matching to derive about 45 billion tie-points. Benefitting from improved image pointing data achieved through photogrammetric block adjustment, we computed about 6.3 billion surface points. By interpolation, we generated a DTM with a lateral spacing of 221.7 m/pixel (192 pixels per degree) and a vertical accuracy of about 30 m. The comparison of the DTM with Mercury Laser Altimeter (MLA) profiles obtained over four years of MESSENGER orbital operations reveals that the DTM is geometrically very rigid. It may be used as a reference to identify MLA outliers (e.g., when MLA operated at its ranging limit) or to map offsets of laser altimeter tracks, presumably caused by residual spacecraft orbit and attitude errors. After the relevant outlier removals and corrections, MLA profiles show excellent agreement with topographic profiles from H6, with a root mean square height difference of only 88 m.