1. Institute of Remote Sensing and Geographical Information Systems, School of Earth and Space Sciences, Peking University, Beijing, China
2. Beijing Key Lab of Spatial Information Integration and Its Applications, Peking University, Beijing, China
3. State Key Laboratory of Media Convergence Production Technology and Systems, Beijing, China
4. Department of Land Surveying and Geo-Informatics, The Hong Kong Polytechnic University, Hong Kong, China
5. National Engineering Research Center of Geographic Information System, China University of Geosciences (Wuhan), Wuhan, China