1. Department of Spatial Information Technology, College of Earth Sciences, Chengdu University of Technology, Chengdu, China
2. Key Laboratory of Geoscience Spatial Information Technology of Ministry of Land and Resources, Chengdu University of Technology, Chengdu, China
3. Department of Physical Geography, College of Tourism and Urban-Rural Planning, Chengdu University of Technology, Chengdu, China
4. Department of Land Surveying and Geo-Informatics, The Hong Kong Polytechnic University, Kowloon, Hong Kong
5. The Sixth Topographic Survey Team, National Administration of Surveying, Mapping and Geoinformation, Chengdu, China
6. Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong University, Chengdu, China