1. Faculty of Geomatics, Lanzhou Jiaotong University, Lanzhou, China
2. National-Local Joint Engineering Research Center of Technologies and Applications for National Geographic State Monitoring, Lanzhou, China
3. Gansu Province Engineering Laboratory for National Geographic State Monitoring, Lanzhou, China
4. State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan, China