1. College of Civil Engineering, Nanjing Forestry University, Nanjing 210037, China
2. School of Geographic Information and Tourism, Chuzhou University, Chuzhou 239000, China
3. Department of Informatics and Telecommunications, National and Kapodistrian University of Athens, 15784 Athens, Greece
4. Department of Mathematics and Computing Science, Saint Mary’s University, Halifax, NS B3P 2M6, Canada