1. College of Surveying and Geo-Informatics, North China University of Water Resources and Electric Power, Zhengzhou 450046, China
2. College of Geological Engineering and Geomatics, Chang’an University, Xi’an 710054, China
3. Hebei Institute of Investigation & Design of Water Conservancy & Hydropower Group Co., Ltd., Tianjin 300202, China
4. School of Electrical and Control Engineering, North China University of Technology, Beijing 100144, China
5. Department of Space Information Engineering, Henan College of Surveying and Mapping, Zhengzhou 450015, China
6. College of Professional Study, Northeastern University, Boston, MA 02115, USA