1. School of Information and Communication Engineering, Center for Information Geoscience, University of Electronic Science and Technology of China, Chengdu, China
2. School of Resources and Environment, Center for Information Geoscience, University of Electronic Science and Technology of China, Chengdu, China
3. Netease (Hangzhou) Network Company, Hangzhou, China
4. College of Computer Science, Sichuan University (SCU), Chengdu, China