1. College of Information and Electrical Engineering, China Agricultural University, Beijing, China
2. Institute of Remote Sensing and Geographic Information System, School of Earth and Space Sciences, the Beijing Key Laboratory of Spatial Information Integration and Its Application, Peking University, Beijing, China
3. Institute of Remote Sensing and Geographic Information System, School of Earth and Space Sciences, and the Beijing Key Laboratory of Spatial Information Integration and Its Application, Peking University, Beijing, China