Scan vs. BIM: Automated geometry detection and BIM updating of steel framing through laser scanning

3D laser scanning can serve the geometric deformation detection of steel structures. However, the process of handling large-scale point clouds remains labor-intensive and time-consuming. This paper presents an automated approach to extracting the precise axes from point clouds and updating the associated BIM model for steel structures. The strategy involves the initial geometry extraction from IFC files and instance segmentation through the reference point cloud simplification and index rules. Then the axes of all components with different sections are detected through the corresponding standard sections and genetic algorithm. Lastly, the geometric information for each component in the BIM is updated by modifying the IFC file. The method is implemented on a steel framing comprising 218 components, indicating that the workflow works effectively with noise and occlusion. The difference in average distances from 218 components to the scanned point cloud is reduced from 17.50 mm before updating to 4.00 mm after updating.