1. SNARS Laboratory, School of Instrumentation and Optoelectronic Engineering, Beihang University, Beijing, China
2. Institute of Remote Sensing Satellite, China Academy of Space Technology, Beijing, China
3. Department of Navigation and Control, Beijing System Design Institute of Electro-mechanic Engineering, Beijing, China
4. Department of Geography, School of Arts and Sciences, National University of Mongolia, Ulaanbaatar, Mongolia