中文摘要：

E-mail： yongxi_gong@163.com; Yong-Xi Gong received the B.Sc. degree in geography from Hubei University in 1997, and the M.Sc. degree in cartography and geographic information systems from Wuhan University in 2003. Currently, he is a Ph.D. candidate majored in geographic information systems at the Institute of Remote Sensing and Geographic Information Systems, Peking University. His research interests include qualitative spatial reasoning, computer graphics and image processing. E-mail： liuyu@urban.pku.edu.cn;Corresponding Author; Yu Liu received the B.Sc., M.Sc., and Ph.D. degrees in human geography, geographic information systems, and software engineering from Peking University in 1994, 1997, and 2003, respectively. He is an associate professor of Peking University. His research includes GI-sciences and GI- software. E-mail： lwu@urban.pku.edu.cn; Lun Wu is a professor of the Institute of Remote Sensing and Geographic Information Systems, Peking University. His research interests include geographic information systems and remote sensing. He has authored more than 100 refereed research articles. E-mail： thanks21@163.com; Yu-Bo Xie received the M.Sc. degree in cartography and geographic information systems from Wuhan University in 2003. Currently, he is a Ph.D. candidate majored in photogrammetry and remote sensing at the State Key Laboratory of Information Engineer in Surveying, Mapping and Remote Sensing, Wuhan University. From July 2003,he is an engineer in image processing and geographic information systems at the North China Institute of Computing Technology. His research interests are geographic information systems and intelligent image processing.