(1. School of Geomatics and Urban Spatial Informatics, Beijing University of Civil Engineering and Architecture, Beijing 100044, China;2. Beijing Key Laboratory for Architectural Heritage Fine Reconstruction & Health Monitoring (Beijing University of Civil Engineering and Architecture), Beijing 100044, China;3. Tianjin Progoo Information Technology Co., Ltd., Tianjin 300380, China;4. Yungang Grottoes Research Institute, Datong 037007, China)
