1. Beijing Key Laboratory of Human Computer Interactions, Institute of Software, Chinese Academy of Sciences, Beijing, China
2. Google, Mountain View, CA, USA
3. State Key Lab of CAD&CG and the College of Computer Science and Technology, Zhejiang University, Hangzhou, China
4. School of Computing Science, Simon Fraser University, Burnaby, BC, Canada
5. School of Artificial Intelligence, Beijing Normal University, Beijing, China
6. Department of Computer Science, ETH Zurich, Zurich, Switzerland