1. Tangshan Institute, Southwest Jiaotong University, Tangshan, China
2. Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong University, Chengdu, China
3. State-Province Joint Engineering Laboratory of Spatial Information Technology of High-Speed Rail Safety, Southwest Jiaotong University, Chengdu, China
4. Chengdu Institute of Natural Resources Survey and Utilization, Chengdu, China