1. Department of Surveying, Mapping and Geoinformation, College of Geographical and Biological Information, Nanjing University of Posts and Telecommunications , Nanjing , Jiangsu 210023 , China
2. Jiangsu Engineering Laboratory for Smart Analysis of Healthy Big Data and Location Based Services , Nanjing , Jiangsu 210023 , China
3. Department of Geography and Resource Management, and Institute of Space and Earth Information Science, The Chinese University of Hong Kong , Shatin , Hong Kong
4. Department of Human Geography and Spatial Planning, Utrecht University , Utrecht , The Netherlands