1. School of Computer Science, South China Normal University, Guangzhou, China
2. Centre for Social Sciences, Southern University of Science and Technology, Shenzhen, China
3. Department of Geography, University of Wisconsin-Madison, Madison, WI, USA
4. State Key Laboratory of Resources and Environmental Information System, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China
5. School of Geography, Nanjing Normal University, Nanjing, China
6. Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing Normal University, Nanjing, China