Enhanced Crack Width Measurement Using GPS Coordinates From Drone Filming

In this study, concrete crack widths were quantified by converting boundary sub-pixels, which were calculated using the Gradient Variation Vector, into 3D ground coordinates following photogrammetry principles. A series of experiments was conducted to validate the proposed method. Initially, twelve virtual cracks of different widths were affixed to a wall, and image-based measurements were conducted. Additionally, field tests entailed capturing images of real cracks on structural surfaces and measuring crack widths at four specified distances for precision assessment. The results revealed distinct patterns. In the virtual crack experiment, a noticeable trend emerged: as crack width decreased and imaging distance increased, measurement errors tended to increase. Conversely, in the actual crack experiment, a consistent trend in measurement accuracy was absent when compared to the virtual crack scenarios. Deviations remained generally minimal, and despite variations, measurement errors stayed largely consistent.