Efficient in-site laser scanning scheme with adaptive angular resolution for long-span bridge geometry measurement

Abstract

For geometrical measurements on long-span bridges, Terrestrial Laser Scanning (TLS) using conventional scanning approach yields the model with over-dense points in close regions and point redundancy in background. This not only hampers the efficiency of on-site scanning but also complicates data post-processing. This study introduces an optimised scanning scheme incorporating automatic identification of bridge key components and fine scan planning with adaptable angular resolutions. A novel method for TLS pose calibration, leveraging geometric feature partitioning and image template matching is proposed, which aids in projecting bridge component labels from the design model to the scan model in the TLS’s view. Considering the substantial disparities in scanning distances across different regions, a multi-segment scan planning is proposed through the clustering of spherical angles and desired angular resolutions. The effectiveness of the proposed method is demonstrated through a field test on a long-span bridge under construction, specifically for deck height measurements.