RIIAnet: A Real-Time Segmentation Network Integrated with Multi-Type Features of Different Depths for Pavement Cracks

Considerable road mileage puts tremendous pressure on pavement crack detection and maintenance. In practice, using a small parameter model for fast and accurate image-based crack segmentation is a challenge. However, current mainstream convolutional neural networks allocate computing resources to the same type of operators, which ignores the impact of different levels of feature extractors on the model performance. In this research, an end-to-end real-time pavement crack segmentation network (RIIAnet) is designed to improve performance by deploying different types of operators in separate layers of the network structure. Based on the extraction characteristics of cracks by convolution, involution, and asymmetric convolution, in the shallow layers the crack segmentation task is matched to extract rich low-level features by the designed asymmetric convolution enhancement module (ACE). Meanwhile, in the deep layers, the designed residual expanded involution module (REI) is used to enhance the high-level semantic features. Furthermore, the existing involution operator that fails to converge during training is improved. The ablation experiment demonstrates that the optimal ratio of the convolution and REI is 1/3 to obtain the optimal resource allocation and ACE improves the performance of the model. Especially compared with seven classical deep learning models of different structures, the results show that the proposed model reaches the highest MIOU, MPA, Recall, and F1 score of 0.7705, 0.9868, 0.8047, and 0.8485, respectively. More importantly, the parameter size of the proposed model is dramatically reduced, which is 0.04 times that of U-Net. In practice, the proposed model can be implemented in images with a high resolution of 2048 × 1024 in real time.