1. Professor, Key Laboratory of Advanced Engineering Surveying of the National Administration of Surveying, Mapping and Geoinformation (NASMG), College of Surveying and Geo-informatics, Tongji Univ., Shanghai 200092, China (corresponding author).
2. Ph.D. Candidate, College of Surveying and Geo-informatics, Tongji Univ., Shanghai 200092, China.
3. Lecturer, College of Surveying and Geo-informatics, Tongji Univ., Shanghai 200092, China.
4. Associate Professor, Nottingham Geospatial Institute, Univ. of Nottingham, Nottingham NG7 2TU, U.K.