Fig. 1. Chessboard images of different cameras. (a) Camera C₀; (b) camera C₁

Fig. 2. Feature matching results in external parameter calibration

Fig. 3. Image matching and reconstruction in 3D-DIC measurement

Fig. 4. Schematic diagram of rigid body displacement caused by the rotation of the propeller hub

Fig. 5. Schematic diagram of the refraction light path

Fig. 6. Displacement results calculated by two methods. (a) Displacement; (b) difference between the measured value and the true value

Fig. 7. Stereo vision measurement system. (a) Diagram of the experimental setup; (b) image observed by camera C₀ ; (c) image observed by camera C₁

Fig. 8. Three-dimensional topographies of the cylindrical surface before and after refraction correction

Fig. 9. Physical image of the 3D-DIC measurement system

Fig. 10. Images observed by two cameras. (a) Camera C₀; (b) camera C₁

Fig. 11. Displacement fields in different directions when the water velocity is 2 m/s

Fig. 12. Displacement fields in different directions when the water velocity is 3 m/s