Uniformity inspection of tack coats through measurement conducted on drone-collected images

Tack coat is a thin asphalt applied between the existing surface and asphalt overlay during road rehabilitation. Its coverage uniformity is vital in providing adhesive bonding between the two layers in the structure. This paper proposes a novel method for automatic uniformity inspection of tack coat coverage using images collected by drones. In this method, color thresholding is first performed to extract coarse region of the tack coat. Then, the boundaries of the tack coat are detected to refine the tack coat region by masking outliers. Next, the region of interest is processed to extract texture features using gray-level co-occurrence. Finally, the texture features are leveraged to grade the tack coat uniformity level using LightGBM. Experiments were conducted to examine the performance of the method. The resulting accuracy signifies the potential of this method in developing high-efficiency and cost-effective solutions to enhance the current tack coat inspection practice.