Assessment of out‐of‐plane structural defects using parallel laser line scanning system

Abstract

A precise parallel laser line scanning system has been developed to assess the depth of out‐of‐plane structural defects on concrete surfaces. This system comprises a digital camera, dual line laser diodes, and positioning rigid arms that create a triangulation‐based setup. Laser lines are distorted when projected onto an out‐of‐plane defect. A new image processing algorithm has been devised to extract depth information from the distorted laser strips. Parallel laser lines are used to ensure that imaged laser strips do not intersect, thereby simplifying the depth assessment of defects at different distances and enabling the generation of defect profiles from a single image. The system has been validated through laboratory and field tests, demonstrating its effectiveness and accuracy. Compared to other noncontact measurement techniques, this system stands out due to its simplicity, cost‐effectiveness, efficiency, and superior accuracy for long‐range measurements, rendering it suitable for on‐site scanning of textureless uneven engineering objects.