1. Electronic Information School, Wuhan University, Wuhan, China
2. Electronic Information School and the Geospatial Information Technology Cooperative Innovation Center, Wuhan University, Wuhan, China
3. School of Computer Science and Engineering, Sun Yat-sen University, Guangzhou, China
4. Electronic Information School, Wuhan University, and the Wuhan Digital and Engineering Institute, Wuhan, China
5. Department of Mathematics and Computer Science, Nicholls State University, Thibodaux, LA, USA
6. Department of Computer Science, Baylor University, Waco, TX, USA