1. College of Computer Science and Technology, Guizhou University, Guiyang, People's Republic of China
2. State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing Science, Wuhan University, Wuhan, People’s Republic of China
3. Institute of Urban Environment Chinese Academy of Sciences, Xiamen, People’s Republic of China
4. College of Geography and Tourism, Hengyang Normal University, Hengyang, People’s Republic of China
5. Department of Geodesy and Geoinformation, TUWien, Vienna, Austria