1. Smart Health Big Data Analysis and Location Services Engineering Lab of Jiangsu Province, Nanjing University of Posts and Telecommunications, Nanjing, Jiangsu, China
2. Geography and Geoinformation Science, George Mason University, Fairfax, VA, USA
3. Key Laboratory of Virtual Geographic Environment, (Nanjing Normal University), Ministry of Education, Nanjing, Jiangsu, China
4. Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing, Jiangsu, China