Open AccessArticle by Ruichun Chang 1,2,3, Dong Hou 1,2,*, Zhe Chen 1,2,3,4,5 and Ling Chen 1,2 1 College of Mathematics and Physics, Chengdu University of Technology, Chengdu 610059, China 2 Digital Hu Line Research Institute, Chengdu University of Technology, Chengdu 610059, China 3 Geomathematics Key Laboratory of Sichuan Province, Chengdu University of Technology, Chengdu 610059, China 4 International Research Centre of Big Data for Sustainable Development Goals (CBAS), Beijing 100094,...