Crack45K: Integration of Vision Transformer with Tubularity Flow Field (TuFF) and Sliding-Window Approach for Crack-Segmentation in Pavement Structures

Recently, deep-learning (DL)-based crack-detection systems have proven to be the method of choice for image processing-based inspection systems. However, human-like generalization remains challenging, owing to a wide variety of factors such as crack type and size. Additionally, because of their localized receptive fields, CNNs have a high false-detection rate and perform poorly when attempting to capture the relevant areas of an image. This study aims to propose a vision-transformer-based crack-detection framework that treats image data as a succession of small patches, to retrieve global contextual information (GCI) through self-attention (SA) methods, and which addresses the CNNs’ problem of inductive biases, including the locally constrained receptive-fields and translation-invariance. The vision-transformer (ViT) classifier was tested to enhance crack classification, localization, and segmentation performance by blending with a sliding-window and tubularity-flow-field (TuFF) algorithm. Firstly, the ViT framework was trained on a custom dataset consisting of 45K images with 224 × 224 pixels resolution, and achieved accuracy, precision, recall, and F1 scores of 0.960, 0.971, 0.950, and 0.960, respectively. Secondly, the trained ViT was integrated with the sliding-window (SW) approach, to obtain a crack-localization map from large images. The SW-based ViT classifier was then merged with the TuFF algorithm, to acquire efficient crack-mapping by suppressing the unwanted regions in the last step. The robustness and adaptability of the proposed integrated-architecture were tested on new data acquired under different conditions and which were not utilized during the training and validation of the model. The proposed ViT-architecture performance was evaluated and compared with that of various state-of-the-art (SOTA) deep-learning approaches. The experimental results show that ViT equipped with a sliding-window and the TuFF algorithm can enhance real-world crack classification, localization, and segmentation performance.