Two-Dimensional Wave Direction Spectrum Inversion Based on Stereo Photography Data

Stereo photography enables continuous observation of three-dimensional ocean waves. At present, however, there is a lack of research on two-dimensional wave direction spectrum estimation based on stereo photography wave observation data, which restricts further application of stereoscopic technology in ocean observation. In view of this situation, based on the stereoscopic wave observation system developed by the Microwave Remote Sensing Laboratory of Ocean University of China and combined with the extended eigenvector method of wave direction spectrum array measurement, the feasibility of inversion of two-dimensional wave spectrum based on stereo photography wave observation data is systematically studied, and the influence of factors such as array arrangement, sampling point spacing, and observation errors of different sea surface sampling points on the two-dimensional wave direction spectrum inversion results is analyzed. The inversion results of wave data measured by stereoscopic photography show that better wave direction spectrum inversion results can be obtained when the distance between sampling points in the array is less than 1/3 wave wavelength and the array of sampling points is pentagonal. By comparing the two-dimensional wave direction spectrum obtained from the stereo photography data with the measurements of the Signature1000 Acoustic Doppler Wave and Current Profiler (AWAC), it is evident that the results obtained from the stereo photography are in good alignment with the measurements of AWAC. Specifically, the correlation coefficients for the effective wave height and mean wave direction obtained from stereo photography and those measured by the AWAC are 0.988 and 0.983, respectively, with average bias of 0.029 m and 0.010°, respectively, the root mean square errors are 0.089 m and 8.844°, respectively.