1. Department of Land Surveying and Geo-Informatics, The Hong Kong Polytechnic University, Hung Hom, Hong Kong
2. Computer Vision Laboratory, ETH Zürich, Zürich, Switzerland
3. Department of Aeronautical and Aviation Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong
4. Department of Mechanical Engineering, University of Hong Kong, Kowloon Tong, Hong Kong