1. Key Laboratory of Virtual Geographic Environment, Ministry of Education of PRC, Nanjing Normal University, Nanjing, China
2. Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing Normal University, Nanjing, China
3. Centre for Advanced Spatial Analysis, University College London, London, UK
4. Interfaculty Department of Geoinformatics, University of Salzburg, Salzburg, Austria
5. Institute of Space and Earth Information Science, The Chinese University of Hong Kong, Hong Kong, China
6. Department of Geography, University of Wisconsin–Madison, Wisconsin, USA