Abstract
Abstract. The ZY-3 is the civil high-resolution optical stereoscopic mapping satellite independently developed by China. The ZY-3 constellation of the twin satellites operates in a sun-synchronous, near-polar, circular 505 km orbit, with a descending location time of 10:30 AM and a 29-day revisiting period. The panchromatic triplet sensors, pointing forward, nadir, and backward with an angle of 22°, have excellent base-to-height ratio, which is beneficial to the extraction of DEM. In order to extract more detailed and highprecision DEM, the ZY-3 (02) satellite has been upgraded based on the ZY-3 (01), and the GSD of the stereo camera has been optimized from 3.5 to 2.5 meters. In the paper case studies using the ZY-3 01 and the 02 satellite data for block adjustment and DEM extraction have been carried out in Liaoning Province of China. The results show that the planimetric and altimetric accuracy can reach 3 meters, which meet the mapping requirements of 1 : 50,000 national topographic map and the design performance of the satellites. The normalized elevation accuracy index (NEAI) is adopted to evaluate the twin satellite stereoscopic performance, and the NEAIs of the twin ZY-3 satellites are good and the index of the ZY-3(02) is slightly better. The comparison of the overlapping DEMs from the twin ZY-3 satellites and SRTM is analysed. The bias and the standard deviation of all the DEMs are better than 5 meters. In addition, in the process of accuracy comparison, some gross errors of the DEM can be identified, and some elevation changes of the DEM can also be found. The differential DEM becomes a new tool and application.
Highlights
The ZY-3 is the civil high-resolution optical stereoscopic mapping satellite independently developed by China
The panchromatic triplet sensors, pointing forward, nadir, and backward with an angle of 22 °, have excellent base-to-height ratio, which is beneficial to the extraction of digital elevation model (DEM)
In order to further evaluate the accuracy of DEM data, a comparative analysis is performed with SRTM DEM data
Summary
The ZY-3 is the civil high-resolution optical stereoscopic mapping satellite independently developed by China. It is mainly used for 1: 50,000 scale topographic mapping. After the completion of on-orbit testing, the two satellites operate at a phase angle of 180 °, forming a stereoscopic mapping satellite constellation. In order to extract more detailed and high-precision DEM, the ZY-3 (02) satellite has been upgraded based on the ZY-3 (01), and the GSD of the stereo camera has been optimized from 3.5 to 2.5 meters. In this paper the accuracy of the bundle adjustment and DEM generation with the overlapping ZY-3 data is studied firstly, and the normalized elevation accuracy index (NEAI) is adopted to evaluate the twin satellite stereoscopic performance. The accuracy of the DEMs from the twin ZY-3 satellites and SRTM is analyzed and compared using the differential DEM method
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