Improvement and Assessment of the Geometric Accuracy of Chinese High-Resolution Optical Satellites

During the 5 years following the launch of CBERS-02B in September 2007, China launched a sequence of high-resolution optical satellites that are able to acquire high-resolution images globally. However, most of the satellites launched before 2012 have such poor geometric accuracy, due to both the low technological level of the hardware and design defects, so that their application (e.g., to surveys of land resources) is greatly restricted. Thus, they cannot meet national demands for high-resolution optical images with good geometric accuracy. Following the launch of ZiYuan3-01 (ZY3-01) on January 9, 2012, the retrieval of its images has demonstrated the excellent geometric accuracy that has led Chinese high-resolution optical satellites (CHROSs) to attract much attention from international researchers. As CHROSs suffer from more complex errors than international commercial satellites, such as SPOT and IKONOS, conventional processes widely used in the international field to improve accuracy cannot be applied to them. This paper focuses on the in-orbit active CHROSs and proposes a series of methods for improvement of geometric accuracy. Using high-accuracy ground control data collected from different areas, the accuracy of CHROSs following the improvement measures is assessed. The results indicate that good geometric accuracy could be achieved using the proposed methods, given the conditions of both the low level of the hardware technology and the inherent design defects of CHROSs.