1. School of Remote Sensing and Geomatics Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China
2. Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China
3. College of Geomatics and Geoinformation, Guilin University of Technology, Guilin 541004, China
4. School of Geography and Information Engineering, China University of Geosciences, Wuhan 430074, China