Yueji Liang, Jianmin Lai, College of Geomatics and Geoinformation, Guilin University of Technology, China; Guobiao Lin, Department of Natural Resources,Chongzuo, China; Chao Ren, Xianjian Lu, Jiyang Li, Zhe Wen, College of Geomatics and Geoinformation, Guilin University of Technology, China