Abstract
The reflected light image method has been developed to measure unsteady wave height distributions. In this method, the gradient vector distribution of water surface height can be obtained through image analysis. And the wave height distribution can be reconstructed from the measured gradient distribution and a known height at one point. In this paper, we made the following modifications to measure the waves around a model ship :(i) Formulation errors in calculating gradient are modified, (ii) Random pattern and grid pattern are used as the reference images, (iii) A new technique to reconstruct height from gradient is applied. Direct cross correlation method is applied to image tracking. But in the case of a wave having large surface curvature, a point in the reference pattern corresponds to several points in the deformed surface image, therefore we used grid pattern as a reference image and tracked the grid points manually.
