1. Assistant Professor, School of Geological Engineering and Geomatics, Chang'an Univ., Xi'an 710064, China (corresponding author).
2. School of Geological Engineering and Geomatics, Chang'an Univ., Xi'an 710064, China.
3. Master’s Candidate, School of Geological Engineering and Geomatics, Chang'an Univ., Xi'an 710064, China.
4. Professor, School of Geological Engineering and Geomatics, Chang'an Univ., Xi'an 710064, China; Professor, LREIS, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.