Automatic fusion of multiple non-destructive testing images and CAD models for industrial inspection

Currently, three complementary non-destructive testing (NDT) methods are available for the examination of the structural integrity of aircraft components. These are ultrasonic, radiographic and shearographic inspection techniques. As the image features generated by each type of inspection technique are very different from one another, each NDT method requires its own highly trained operators to accurately classify the observed image features as component defects or image artefacts inherent in that particular NDT method. Consequently, the use of different NDT methods, as independent and separate processes for the detection of different types of defects, significantly increases the inspection time (especially for large primary structures) and the overall manufacturing cost. One possible method to achieve cost savings while maintaining a full defect detection capability is to combine the three NDT images by fusion, because this enables defect interpretation to be carried out on one fused image only thereby reducing the overall inspection time. A novel approach is presented to achieve fusion of multiple NDT images automatically. The proposed approach is based on matching each individual NDT image of the component under inspection to its wire-frame CAD model before combining them. A significant advantage of the proposed approach is the inclusion of the wire-frame in the final fused image to provide a geometric reference for defect locations.