[1] Chinese Acad Surveying & Mapping, Beijing 100830, Peoples R China
[2] Surveying & Mapping Inst, Lands & Resource Dept Guangdong Prov, Guangzhou 510700, Peoples R China
[3] Lanzhou Jiao Tong Univ, Fac Geomat, Lanzhou 730070, Peoples R China
[4] Gansu Prov Engn Lab Natl Geog State Monitoring, Lanzhou 730070, Peoples R China
[5] Natl Local Joint Engn Res Ctr Technol & Applicat N, Lanzhou 730070, Peoples R China