Fig. 1. Bisic principle of DVC

Fig. 2. Schematic diagram of the gray level residual field calculation process

Fig. 3. Schematic diagram of data interpolation based on 3D Delaunay triangulation algorithm

Fig. 4. Schematic illustration of the implementation of tricubic interpolation (k can be -1, 0, 1, 2)

Fig. 5. Simulated volume images of 200 voxel×200 voxel×200 voxel. (a) Reference volume image; (b) deformed volume image; (c) differential image between reference and deformed volume images

Fig. 6. Measurement results by local DVC in simulation experiment. (a) v displacement field; (b) ZNCC coefficient field; (c) von-mises strain field

Fig. 7. Gray level residual fields and grayscale histogram. (a) Uncorrected; (b) corrected; (c) threshold processed; (d) grayscale histogram

Fig. 8. Real test results. (a) Reference volume image; (b) deformed volume image; (c) differential image between the two volume images

Fig. 9. Results obtained by local DVC in real test. (a) ZNCC coefficient field; (b) von-mises strain field; (c) gray level residual field

Fig. 10. Slice maps of different positions of residual gray field and 3D view of the damage location within the nodular graphite cast iron volume image. (a) y=40 voxel slice map; (b) y=85 voxel slice map (the left is the original slice map, and the right is the post-processing slice map); (c) 3D view (the damage region is blue and the nodular graphite is dark)