1. Chinese Academy of Surveying and Mapping, Beijing 100830, China
2. Surveying and Mapping Institute Lands and Resource Department of Guangdong Province, Guangzhou 510700, China
3. Faculty of Geomatics, Lanzhou Jiao Tong University, Lanzhou 730070, China
4. Gansu Provincial Engineering Laboratory for National Geographic State Monitoring, Lanzhou 730070, China
5. National-Local Joint Engineering Research Center of Technologie and Applications for National Geographic State Monitoring, Lanzhou 730070, China