Fig. 1. Schneider coding mark before and after projection transformation. (a) Marked point of object plane; (b) marked point of image plane

Fig. 2. Principle diagram of line edge segmentation. (a) Principle of segmentation; (b) result of segmentation

Fig. 3. Simulated straight line edge. (a) Simulated line image; (b) local enlarged image

Fig. 4. Comparison of center extraction methods for the simulation image. (a) Simulation image; (b) local enlarged image

Fig. 5. Effect of radius ratio on accuracy of extraction center

Fig. 6. Effect of the number of code segments on the accuracy of the extraction center

Fig. 7. Effect of Gaussian noise standard deviation on the accuracy of extraction center

Fig. 8. Schematic diagram of object plane rotation around y axis

Fig. 9. Effect of rotation angle change on center extraction error

Fig. 10. Effect of radius proportional change on center extraction error

Fig. 11. Comparison of center extraction on test target. (a) Test target image; (b) comparison of center extraction

Fig. 12. Target object figure of camera calibration

Fig. 13. Reprojection errors of camera calibration. (a) Ellipse fitting method; (b) our proposed method