1. School of Civil Engineering, Qingdao University of Technology, Qingdao, China
2. School of Electrical Engineering, University of Jinan, Jinan, China
3. Department of Aeronautical Instrument and Electrical Control Engineering and Command, Qingdao Branch of Naval Aviation University, Qingdao, China
4. State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan, China