1. School of Geography and Information Engineering, China University of Geosciences, Wuhan, China
2. China University of Geosciences, National Engineering Research Center for Geographic Information System, Wuhan, China
3. GRID, Faculty of Built Environment, University of New South Wales, Sydney, Australia
4. GIScience Research Group, Institute of Geography, Heidelberg University, Heidelberg, Germany
5. GIScience Center, Department of Geography, University of Zurich, Zurich, Switzerland