1. School of Geographic and Biologic Information, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
2. School of Communications and Information Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
3. School of Earth Sciences and Engineering, Hohai University, Nanjing 211100, China
4. School of Network and Communication, Nanjing Vocational College of Information Technology, Nanjing 210023, China
5. Hubei Provincial Key Laboratory for Geographical Process Analysis and Simulation, Central China Normal University, Wuhan 430079, China
6. School of Civil Engineering and Architecture, Changzhou Institute of Technology, Changzhou 213032, China
7. Jiangsu Geologic Surveying and Mapping Institute, Nanjing 211102, China