1. College of Computer Science and Technology, Qingdao University , Ningxia Road, Qingdao, 266071 , China
2. State Key Laboratory of Public Big Data, Guizhou University , Jiaxiu South Road, Huaxi District, Guiyang, 550025 , China
3. Beijing Key Laboratory of Urban Spatial Information Engineering , Nanlishi Road, Xicheng District, Beijing, 100038 , China