Optical satellite sensor and positioning accuracy analysis for the Hongqi-1-H9 wide-range satellite in different terrains

The excellent performance of geometric positioning of a newly launched satellite will greatly broaden its application field. Launched on January 15, 2020, the Hongqi-1-H9 wide-range satellite is the largest sub-meter-level satellite worldwide and the first ton-level commercial remote sensing satellite in China, with a resolution of less than 1 m and a swath width of 136 km. This study was aimed at assessing the geometric positioning accuracy of this newly launched satellite considering three aspects, namely, the circle error accuracy, rational polynomial coefficient-based direct geometric positioning accuracy and ground control point-based absolute positioning accuracy under urban, plain, and mountainous areas, with different topographies. The results of the conducted experimental investigation indicated that the Hongqi-1-H9 satellite could exhibit a high positioning accuracy in planar and vertical directions for different terrains. In particular, for our experimental areas with a low topography and few surface structures, the geometric positioning accuracy of the Hongqi-1-H9 satellite imagery was less than 4m and 2 m in the planimetry and elevation directions, respectively. These characteristics can promote the application of the Hongqi-1-H9 satellite images in agricultural surveys, target detection, and land surveys, among other domains.