HIGH-PRECISION CRACK WIDTH MEASUREMENT IN REINFORCED CONCRETE USING MOBILE LIDAR AND POINT CLOUD ANALYSIS

This study investigates the effectiveness of consumer-grade mobile LiDAR systems for measuring crack widths on a laboratory-tested reinforced concrete (RC) beam specimen. The observed cracks correspond to flexural surface cracks formed under vertical loading. A comprehensive workflow was developed, incorporating geometric calibration using spatial measurement targets (SMTs), photogrammetric validation, and comparative analysis across six mobile LiDAR applications. Calibration tests demonstrated that SMT-supported scans achieved sub-millimeter accuracy, with average deviations around ±0.50 mm, while unreferenced scans showed errors exceeding 1.5 mm. Crack width measurements performed in CloudCompare and AutoCAD showed strong agreement with reference visual measurements, confirming the suitability of LiDAR-derived point clouds for quantitative crack assessment. Comparative evaluation of mobile applications revealed that Canvas, RealityScan, and Scaniverse produced the most accurate and homogeneous point distributions, enabling reliable sub-millimeter measurements. In contrast, high-density outputs from PIX4Dcatch and Sitescape resulted in overestimated crack widths due to point clustering and surface layering effects. The results highlight the importance of geometric calibration, point cloud distribution quality, and scanning protocols in achieving accurate and repeatable crack width measurements. Overall, the proposed methodology demonstrates the potential of mobile LiDAR technology as a low-cost and practical tool for quantitative surface crack assessment in structural health monitoring applications.