1. School of Computer Science and Technology, Hainan University, Haikou, China
2. Zhongnan Engineering Corporation Limited, Power China, Changsha, China
3. National Engineering Research Center for Geographic Information System, China University of Geosciences, Wuhan, China
4. School of Geography and Environment, Jiangxi Normal University, Nanchang, China
5. College of Surveying and Geo-Informatics, Tongji University, Shanghai, China