Fig. 1. Underwater stereo camera imaging model. (a) Common refractive flat imaging; (b) independent refractive flat imaging

Fig. 2. Mathematical model of underwater stereovision measurement system

Fig. 3. Refractive imaging properties of camera underwater. (a) Intersection of an underwater refracted ray extension line with a common axis of the refractive surface; (b) refractive flat constraints

Fig. 4. Underwater stereovision system test bed

Fig. 5. Reconstruction results of underwater targets points. (a) Images of left and right cameras; (b) three-dimensional information of underwater target points

Fig. 6. Three-dimensional information of underwater target points. (a) Reconstructed underwater target point ignoring refraction; (b) reconstructed underwater target point with our method

Fig. 7. Flatness of reconstructed underwater target. (a) Flatness of reconstructed underwater target point ignoring refraction; (b) flatness of reconstructed underwater target point with our method

Fig. 8. Comparison of standard length measurement error in air and underwater

Fig. 9. Comparison of all standard length measurement errors in air and underwater on target