Automated Installation Checking and Hanger Pre-Adjustment for Stone Curtain Walls Based on UAV Photogrammetry and Terrestrial Laser Scanning

The installation quality of multi-point attachment unit systems in stone curtain walls depends on the geometric compatibility between unit-side hanger arrays and support-side attachment nodes (SSANs). However, deviations from on-site welding, adapter component installation, and end-connection positioning can accumulate within individual SSANs, affecting hanger seating, synchronized multi-point attachment, and joint-width coordination. Therefore, this study proposes an installation checking and hanger pre-adjustment method based on UAV photogrammetry and terrestrial laser scanning (TLS). First, UAV close-range photogrammetry and TLS are used to acquire complementary point clouds of the installed SSANs and the surrounding curtain wall inspection area. Second, SSANs and their internal components are extracted, and end-connection positioning features are determined using a Point–Line–Plane geometric framework. Third, the measured geometric relationships among SSAN positioning features are converted into target hanger layout parameters to assess installation compatibility and generate hanger pre-adjustment and installation decisions. Finally, the proposed method was evaluated in a real project. The average total installation time per curtain wall unit was 48 min compared with 70 min for the traditional method, while the average number of on-site adjustments per curtain wall unit was 4 compared with 15 for the traditional method. The joint-width range was 18.6–23.1 mm compared with 16.8–27.4 mm. The field comparison showed lower average installation time and adjustment counts and a narrower joint-width range in the proposed-method group.