1. Department of Land Surveying and Geo-Informatics, The Hong Kong Polytechnic University, Kowloon, Hong Kong
2. School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan, Hubei 430070, China
3. School of Remote Sensing and Information Engineering, Wuhan University, 129 Luoyu Road, Wuhan, Hubei 430079, China