1. School of Electronics Information and Communications, Huazhong University of Science and Technology, Wuhan, China
2. Alibaba.autonavi Software Co., Ltd., Beijing, China
3. Department of Mathematics, Informatics and Computational Sciences, Sokoine University of Agriculture, Morogoro, Tanzania
4. State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan, China