国家基础科学人才培养基金资助项目J1103409;数字制图与国土信息应用工程国家测绘地理信息局重点实验室开放研究基金资助项目GCWD201408.The National Science Foundation for Fostering Talents in Basic Research of the National Natural Science Foundation of China,No.J1103409;Open Research Fund Program of Key Laboratory of Digital Mapping and Land Information Application Engineering,No.GCWD201408.