1. School of Computer Science and Engineering, Beihang University, Beijing, China
2. Department of Computer Science, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
3. Beijing Engineering Research Center of Mixed Reality and Advanced Display, School of Optics and Electronics, Beijing Institute of Technology, Beijing, China
4. Sixth Medical Center, Chinese PLA General Hospital, Beijing, China
5. School of Computer Science and Engineering and the Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing, China