1. School of Spatial Informatics and Geomatics Engineering, Anhui University of Science and Technology, Huainan, China
2. Department of Geography and Earth Science, The University of North Carolina at Charlotte, Charlotte, NC, USA
3. School of Mining and Geomatics, Hebei University of Engineering, Handan, China
4. School of Environment Science and Spatial Informatics, China University of Mining and Technology, Xuzhou, China