Stereo Evaluation of CARTOSAT-1 Data on Test Site 5 - First DLR Results
Stereo Evaluation of CARTOSAT-1 Data on Test Site 5 - First DLR Results
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在测试站点 5 上对 CARTOSAT-1 数据进行立体评估 - 第一个 DLR 结果
DOI：
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发表时间：
2006
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通讯作者：
P. Reinartz
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作者：
M. Lehner;R. Müller;P. Reinartz
德国航天中心遥感技术研究所在开发星载立体扫描仪（中尺度光学观测系统、多尺度光学观测系统）和相应的立体评价软件系统方面有20多年的历史。该研究所作为德国（巴伐利亚东南部，试验中心尚未纳入C-SAP列表）和西班牙（加泰罗尼亚，TS 10）试验中心的主要研究者参加了CARTOSAT-1科学评估计划（C-SAP），2003-4年还对SPOT-5 HRS SAP进行了PI评价。
由于加泰罗尼亚（试验场10）的CARTOSAT-1数据与现有的地面实况不符，与国际协调委员会的谈判提出了一套新的合适的地面实况。不幸的是，这一新的参考数据对于C-SAP的I期来说来得太晚了。因此，就C-SAP第一阶段而言，已商定作为CoI参与评价试验场TS 5（Mausanne-les-Alpilles，法国）的CARTOSAT-1数据。
对于C-SAP的第一阶段，没有提供CARTOSAT-1的明确外部和内部定向数据。相反，有理多项式函数（RPC）是由分发印度机构提供的，作为每个场景的通用传感器模型。因此，只有固有的RPC模型的定向精度是通过比较建立可用的地面实况。地面控制点用于校正RPC（偏差校正和仿射变换）。对由此产生的各种残差进行评估和评论。从这些第一次调查可以看出，原来的RPC的偏移量是在公里的顺序，这是没有预料到的。偏差校正以地面控制点（GCP）处的残差结束，其顺序为几个像素，也显示系统行为。这导致的结论，RPC必须纠正仿射变换。后者导致残差在1像素的顺序，这是令人满意的调查开始。DSM精度通过前方交会中的残差（匹配的连接点云）和通过最小二乘平差（全DEM/DSM比较）计算参考DEM和计算DSM之间的3D位移来评估。使用RPC的仿射变换校正，实现了3-4 m的DEM/DSM高度差的标准偏差，这在考虑固有的DEM/DSM差异时是非常好的。
DLR's Remote Sensing Technology Institute has more than 20 years of history in developing spaceborne stereo scanners (MEOSS, MOMS) and the corresponding stereo evaluation software systems. The institute takes part in CARTOSAT-1 Scientific Assessment Program (C-SAP) as a principal investigator for German (Southeast Bavaria, test site not yet included in the C-SAP list) and Spanish (Catalonia, TS10) test sites for which also PI evaluations for SPOT-5 HRS SAP had been done in 2003-4.
As CARTOSAT-1 data of Catalonia (test site 10) did not correspond to the available ground truth, negotiations with ICC brought forward a new fitting set of ground truth. Unfortunately, this new reference data came too late for phase I of C-SAP. Thus, for phase I of C-SAP participation as a CoI in the evaluation of CARTOSAT-1 data for test site TS5 (Mausanne-les-Alpilles, France) has been agreed upon.
For phase I of C-SAP no explicit exterior and interior orientation data of CARTOSAT-1 have been given. Instead, rational polynomial functions (RPC) are provided by the distributing Indian agency as a universal sensor model for each scene. Thus, only the inherent orientation accuracy of the RPC models is established by comparison to the available ground truth. Ground control points are used to correct the RPC (bias correction and also affine transformations). The resulting various residuals are assessed and commented. From these first investigations it can be seen that the offset of the original RPC is in the order of kilometres which was not expected. Bias correction ends up with residuals at ground control points (GCP) in the order of several pixels showing also systematic behaviour. This leads to the conclusion that RPC have to be corrected with affine transformations. The latter lead to residuals in the order of 1 pixel which is satisfactory for the start of investigations. DSM accuracies are assessed via residuals in forward intersection (tie point cloud from matching) and through calculation of 3D shifts between reference DEM and calculated DSM by least squares adjustment (full DEM/DSM comparison). Using affine transformation correction of RPC a standard deviation of the DEM/DSM height differences of 3-4 m is achieved which is very good when taking the inherent DEM/DSM differences into account.