1. School of Electronic Information Wuhan University Wuhan China
2. Key Laboratory of Geospace Environment and Geodesy Ministry of Education Wuhan China
3. State Key Laboratory of Information Engineering in Surveying Mapping and Remote Sensing Wuhan University Wuhan China
4. Guizhou Normal University Guiyang China
5. Electrical and Computer Engineering Department Miami University Oxford OH USA
6. Key Laboratory of Earth and Planetary Physics Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China