1. Institute of Surveying and Mapping, Information Engineering University, Zhengzhou, Henan, China
2. Key Laboratory of Spatiotemporal Information Perception and Fusion Technology, Ministry of Land and Resources, Beijing, China
3. Henan Collaborative Innovation Center of Geo-Information Technology for Smart Central Plains, Zhengzhou, Henan, China
4. China National Administration of GNSS and Applications (CNAGA), Beijing, Hebei, China