Fig. 1. Image before and after cropping. (a) Image before cropping; (b) image after cropping

Fig. 2. Result of the gray center of gravity method

Fig. 3. Comparison of results before and after primary smoothing

Fig. 4. Comparison of two smoothing results

Fig. 5. Center line of the upper laser stripe on the standard block and its extraction results. (a) Cylinder standard block; (b) depth standard block

Fig. 6. Error of standard block. (a) Diameter error; (b) depth error

Fig. 7. Four typical line types. (a) Straight line; (b) bolt; (c) curve; (d) broken line

Fig. 8. Laser fringe pictures under different illumination conditions