Huan Li, Peking University, Beijing, China, Wei Wan, Peking University, Institute of Remote Sensing and Geographic Information System, Beijing, China, Hongjie Xie, University of Texas at San Antonio, San Antonio, TX, United States, Guoqing Zhang, Inst. of Tibetan Plateau Resea, Beijing, China and Yang Hong, Peking University, Institute of Remote Sensing and GIS, School of Earth and Space Sciences, Beijing, China