1. School of Cyber Science and Engineering, Sichuan University, Chengdu 610065, China
2. Sichuan Forestry and Grassland Survey and Planning Institute, Chengdu 610084, China
3. School of Information Science and Technology, Beijing Forestry University, Beijing 100083, China
4. Institute of Remote Sensing and Geographic Information System, School of Earth and Space Sciences, Peking University, Beijing 100871, China