Digital Preservation of Ancient Timber Structures Through Integrated TLS-UAV-BIM Reverse Modeling: A Case Study in Gansu Province, China

Heritage timber buildings face accelerating deterioration, yet traditional documentation methods lack the precision required for authentic conservation. This research proposes an integrated Building Information Modeling (BIM) reverse modeling framework combining terrestrial laser scanning (TLS), unmanned aerial vehicle (UAV) photogrammetry, and advanced point cloud processing for heritage building conservation in Gansu Province, China. Multi-source data fusion (Leica RTC360 TLS + DJI Phantom 4 RTK UAV) achieves 97.3% coverage completeness with 745.3 pts/cm² average density across diverse architectural components. The proposed registration algorithm reduces error by 69% (2.8 mm RMSE) while accelerating processing by 53% compared to conventional methods. BIM-based defect detection improves accuracy from 60% to 91% for six common pathologies while reducing inspection time by 73%. Applied to Gansu's 16,895 heritage sites, this framework provides precise digital archives, structural health assessment, and VR/AR visualization capabilities, advancing heritage conservation technology.