1. Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control, School of Environment, Nanjing Normal University, Nanjing, China
2. Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing, China
3. School of Electronics and Information Engineering, Sias International University, Xinzheng, China
4. Department of Geographical Sciences, University of Alabama, Tuscaloosa, AL, USA