1. University of Calgary, Schulich School of Engineering, Department of Geomatics Engineering, 2500 University Drive NW, Calgary, T2N 1N4, Canada
2. PCI Geomatics, 90 Allstate Parkway, Suite 501, Markham, Ontario, L3R 6H3, Canada
3. Wuhan University, LIESMARS, 129 Luoyu Road, Wuhan, China
4. Shandong University of Science and Technology, College of Geomatics, 579 Qian Gang Wan Road, Qingdao, Shandong 266590, China