1. Image Processing Center, School of Astronautics, Beihang University, Beijing 100191, China
2. Beijing Key Laboratory of Digital Media, Beihang University, Beijing 100191, China
3. State Key Laboratory of Virtual Reality Technology and Systems, Beihang University, Beijing 100191, China
4. Department of Guidance, Navigation and Control, School of Astronautics, Beihang University, Beijing 100191, China