Surface Defect Detection Method for Industrial Products Based on Photometric Stereo and Dual Stream Feature Fusion Network

Surface defect detection is an important part of the modern industrial production process. The existing visual defect detection methods generally achieve detection by analyzing a single RGB or grayscale image of the target object and using differential features between the defect and the background. They are suitable for objects with a large difference between the target and the background, such as the detection of metal surface oxidation and spot defects. However, the simple RGB image cannot effectively characterize the 3D defect features such as dents and bulges, which are mainly formed by depth changes, ultimately resulting in missed detection. To this end, this paper extracted the 3D geometric appearance information of the object surface to be tested according to multi-directional light imaging and photometric stereo principle. Next, the original multi-directional light images were effectively fused using the contrast pyramid fusion algorithm to obtain the enhanced 2D RGB fusion image features of the defects. Then, on the basis of the multi-target detection framework YOLOv5, with the above geometric appearance and RGB fusion images as inputs, a defect detection network model based on dual stream feature fusion detection network model was constructed. The model introduces the spatial channel attention residual module and the gated recurrent unit (GRU) feature fusion module and is able to organically fuse the different modal features at multiple levels to realize the effective extraction of the 2D RGB and 3D appearance information of the surface defects, so as to achieve the purpose of dealing with the detection of 2D and 3D defects at the same time. Finally, the detection experiments were conducted on the surface defects of several typical industrial products. The results show that mAP of the method in the paper is above 90% on several datasets, and it can simultaneously cope with the detection of 2D and 3D defects, so the detection performance is better than that of the current mainstream methods, and it can meet the detection requirements of different industrial products.