1. School of Information Science and Technology, Southwest Jiaotong University, Chengdu, China
2. School of Information Science and Technology and the National Engineering Laboratory of Integrated Transportation Big Data Application Technology, Southwest Jiaotong University, Chengdu, China
3. Faculty of Geoscience and Environmental Engineering, Southwest Jiaotong University, Chengdu, China
4. Chinese Academy of Sciences, Aerospace Information Research Institute, Beijing, China
5. Department of Aerospace Engineering Sciences, University of Colorado Boulder, Boulder, CO, USA