1. College of Geodesy and Geomatics, Shandong Univ. of Science and Technology, Qingdao 266590, CN
2. State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and Ministry of Science and Technology, Shandong Univ. of Science and Technology, Qingdao 266590, CN, e-mail: jinyunguo1@126.com
3. College of Geodesy and Geomatics, Shandong Univ. of Science and Technology, Qingdao 266590, CN, e-mail: yuhongjuan123@163.com
4. College of Earth Science and Engineering, Hohai Univ., Nanjing210098, CN, e-mail: liwang@hhu.edu.cn
5. College of Geodesy and Geomatics, Shandong Univ. of Science and Technology, Qingdao 266590, CN, e-mail: xinliu1969@126.com
6. State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and Ministry of Science and Technology, Shandong Univ. of Science and Technology, Qingdao 266590, CN, e-mail: kqlabc3334@hotmail.com
7. Chinese Academy of Surveying and Mapping, Beijing 100830, CN, e-mail: zcm@casm.ac.cn