1. School of Civil Engineering and Geomatics, Shandong University of Technology, Zibo 255049, China
2. State Key Laboratory of Resources and Environmental Information System, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
3. Hunan Provincial Key Laboratory of Geo-Information Engineering in Surveying, Mapping and Remote Sensing, Hunan University of Science and Technology, Xiangtan 411201, China
4. Chongqing Road Secondary School, Zibo 255000, China