1. School of Computer Science, Nanjing University of Information Science and Technology, Nanjing 210044, China
2. Jiangsu Key Laboratory of Image and Video Understanding for Social Safety, Nanjing University of Science and Technology, Nanjing 210094, China
3. Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology (CICAEET), Nanjing University of Information Science & Technology, Nanjing 210044, China
4. Research Institute of Resource Information Techniques, Chinese Academy of Forestry (CAF), Beijing 100091, China