1. Peng Cheng Laboratory, Shenzhen, China
2. Chongqing Key Laboratory of Image Cognition, College of Computer Science and Technology, Chongqing University of Posts and Telecommunications, Chongqing, China
3. Department of Computer Science, City University of Hong Kong, Kowloon Tong, Hong Kong
4. State Key Laboratory of Virtual Reality Technology and Systems, School of Computer Science and Engineering, Beihang University, Beijing, China