1. College of Surveying and Geo-Informatics, Shandong Jianzhu University, Jinan 250101, China
2. College of Geodesy and Geomatics, Shandong University of Science and Technology, Qingdao 266590, China
3. Zhengzhou Branch, Nanjing Institute of Surveying, Mapping and Geotechnical Investigation, Co., Ltd., Zhengzhou 450007, China
4. Wuhan Branch, Changjiang Space Information Technology Engineering Co., Ltd., Wuhan 430010, China