1. School of Computer Science and Engineering, Xi’an University of Technology, Xi’an, China
2. Department of Geography and Spatial Information Techniques, Ningbo University, Ningbo, China
3. Faculty of Electrical and Computer Engineering, University of Iceland, Reykjavik, Iceland
4. Shaanxi Joint Laboratory of Artificial Intelligence, School of Electronic Information and Artificial Intelligence, Shaanxi University of Science and Technology, Xi’an, China