1. School of Resource and Environmental Sciences, Wuhan University, Wuhan 430079, China
2. Key Laboratory of Geographic Information System, Ministry of Education, Wuhan 430079, China
3. Key Laboratory of Digital Mapping and Land Information Application Engineering, National Administration of Surveying, Mapping and Geo-Information, Wuhan 430079, China
4. School of Geospatial Engineering and Science, Sun Yat-sen University, Zhuhai 519082, China