1. School of Environment Science and Spatial Informatics, China University of Mining and Technology, Xuzhou 221116, China
2. State Key Laboratory for Geo-Information Engineering, Xi’an Research Institute of Surveying and Mapping, Xi’an 710054, China
3. Institute of Space Science, Shandong University, Weihai, Shandong 264209, China
4. School of Humanity and Law, Beijing University of Civil Engineering and Architecture, Beijing 102616, China