Fig. 1. Model of underwater measurement based on refraction

Fig. 2. Error analysis of 3D measurement due to image point extraction error

Fig. 3. Design of projection model in structured light system（a） The model of projection； （b）~（e） Multi-field center rotation projection models

Fig. 4. Stripe decoding of image under turbid water

Fig. 5. Example of stripe decoding rules for the first field measurement pattern

Fig. 6. World coordinates and imaging coordinates of corners on planar target with checkerboard

Fig. 7. Principle of light-plane calibration

Fig. 8. Components of underwater structured light system

Fig. 9. Underwater image acquisition sequence （a）~（e） Measurement images of projection period with five fields

Fig. 10. Underwater measurement process of bottle

Fig. 11. Analysis of image and stripe extraction results in different turbid water （a0）~（a3） Images of different turbid water； （b0）~（b3） Binary images of different turbid water； （c0）~（c3） Stripe extraction in different turbid water； （d0）~（d3） Detail of stripe extraction

Fig. 12. 3D results of planar object under different turbid water（a0）~（a3） Measurement surfaces under clear water and three different turbid water； （b0）~（b3） Results of plane fitting residuals under clear water and three different turbid water

Fig. 13. Error of stripe extraction and 3D vision measurement due to different turbid water