1. Department of Geography, Nanjing Normal University, Nanjing, China
2. Nanjing Normal University, Nanjing, China
3. Department of Mathematics Faculty of Science and Technology, University of Macau, Macau, China
4. Hainan University, Hainan, China
5. Airborne HydroMapping GmbH, Innsbruck, Austria
6. State Key Discipline of Cartography and GIS, Nanjing Normal University, Nanjing, China
7. School of geography and science, Nanjing Normal University, Nanjing, China