Fig. 1. Underwater camera imaging light path

Fig. 2. Four-dimensional parametric expression of light

Fig. 3. Refraction imaging model of underwater camera

Fig. 4. Underwater binocular stereo vision model

Fig. 5. Schematic of multi-layer refraction light path

Fig. 6. Calibration results under different background light

Fig. 7. Simulation model

Fig. 8. X，Y，Z error distribution of three dimensional points

Fig. 9. Experimental environment

Fig. 10. Calibration scene in air

Fig. 11. Underwater calibration scene

Fig. 12. A set of images taken by underwater calibration

Fig. 13. Reprojection error of different test images

Fig. 14. Diagram of the 10 positions of the bat

Fig. 15. Schematic of experimental results