Fig. 1. Experimental setup for multi-camera three-dimensional shape measuring system using digital fringe projection techniques
Fig. 2. Directional circular pattern for planar calibration target
Fig. 3. (a)-(d) Images of the flexible calibration target grabbed by different cameras. (a) Camera 1; (b) camera 2; (c) camera 3; (d) camera 4. (e)-(h) Images grabbed by camera 1 of the flexible calibration target with different shapes. (e) Shape 1; (f) shape 2; (g) shape 3; (h) shape 4
Fig. 4. Calibration error diagram from camera 2 to camera 1 in quaternary quadratic model
Fig. 5. Measurement results of 4 different polynomial models. (a) Ternary quadratic model; (b) ternary cubic model; (c) quaternary quadratic model; (d) quaternary cubic model
Fig. 6. Measurement results of different FOV overlapping. (a) 1/2; (b)1/3; (c) 1/4; (d) 1/6
Fig. 7. Image of multiple objects to be measured
Fig. 8. 3D reconstruction images. (a) Camera 1; (b) camera 2; (c) camera 3; (d) camera 4; (e) merged image
Fig. 9. Step standard block and its size
Fig. 10. 3D reconstruction image of the step standard block by camera 2 using (a) method 1 and (b) method 2
Fig. 11. Standard ball
Fig. 12. Fitted spheres based on the spherical crown point cloud
Camera No. | Position No. | Step 2 distance /mm | Step 3 distance /mm | |
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Method 1 | | Method 2 | Method 1 | Method 2 |
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| 1 | 5.708 | 5.929 | 12.421 | 12.607 | 2 | 2 | 5.642 | 5.567 | 12.533 | 12.428 | | 3 | 5.723 | 5.501 | 12.635 | 12.781 | | 1 | 5.896 | 5.868 | 13.226 | 12.998 | 3 | 2 | 5.742 | 5.578 | 12.495 | 12.977 | | 3 | 5.636 | 5.745 | 12.718 | 12.589 | | 1 | 5.980 | 6.252 | 13.150 | 13.477 | 4 | 2 | 5.747 | 5.833 | 12.573 | 12.513 | | 3 | 6.271 | 6.379 | 13.059 | 13.584 |
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Table 1. Measurement results of the step standard block
Nominal value /mm | Center distance /mm | Average /mm | RMSE /mm |
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400.0 | 401.42 | 398.84 | 399.11 | 400.57 | 399.66 | 400.37 | 0.98 | | 401.16 | 400.71 | 401.73 | 400.41 | 400.13 | | | 600.0 | 599.86 | 600.81 | 599.35 | 600.96 | 598.93 | 599.75 | 0.87 | | 598.82 | 600.70 | 598.86 | 600.33 | 598.92 | | | 721.1 | 722.16 | 721.27 | 720.63 | 722.86 | 721.21 | 721.53 | 0.92 | | 720.13 | 722.39 | 721.82 | 721.98 | 720.90 | | |
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Table 2. Measurement results of the sphere center distance