1. GIScience Research Group, Institute of Geography, Heidelberg University, Heidelberg, Germany
2. Institute of Data Science Institute, German Aerospace Center (DLR), Jena, Germany
3. Faculty of Geography, Philipps University of Marburg, Marburg, Germany
4. Department of Civil and Environmental Engineering, Norwegian University of Science and Technology, Trondheim, Norway
5. Department of Computer Science, National University of Singapore, Singapore
6. School of Geography and Information Engineering, China University of Geosciences, Wuhan, China
7. National Engineering Research Center for Geographic Information System, Wuhan, China