1. Key Laboratory of New Technology for Construction of Cities in Mountain Area (Ministry of Education), Chongqing University, Chongqing 400045, China
2. School of Civil Engineering, Chongqing University, Chongqing 400045, China
3. Chongqing Academy of Surveying and Mapping, Chongqing 401121, China
4. Technology Innovation Center for Spatio-Temporal Information and Equipment of Intelligent City, Ministry of Natural Resources, Chongqing 401121, China