1. State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan, Hubei, PR China
2. Department of Geography, University of Zurich, Zurich, Switzerland
3. Collaborative Innovation Center of Geospatial Technology, Wuhan, PR China
4. China Mobile Group Hubei Company Limited, Wuhan, China
5. Department of Geography, Ghent University, Ghent, Belgium