Research On Ocean Wave Parameter Observation Technology Based On Binocular Vision

Waves are a very familiar and significant physical phenomenon generated in the ocean,whether it is for the exploitation of marine resources or for the maritime transportation industry,the measurement and analysis of wave motion parameters is the basic work of understanding,studying,and utilizing waves,and is of great significance.In this paper,binocular cameras are used to continuously photograph the sea surface and obtain ocean wave images,and then digitally process the obtained images to realize non-contact measurement of ocean wave parameters based on binocular vision.First of all,this subject has carried out parameter demarcation and stereo rectification for the binocular camera.The left and right cameras were demarcated separately using the Zhang Zhengyou camera rectification method to obtain the internal parameters and distortion coefficients of the left and right cameras.Exterior parameters are demarcated to obtain the rotation matrix R and translation vector t of the right camera relative to the left camera.The stereo correction based on Bouguet algorithm was used to put the left and right images taken by the binocular camera in the state of coplanar and line alignment,which reduces the complexity of reconstruction algorithm of the three-dimensional coordinates.The calibrated and corrected camera is used to continuously shoot the sea surface,after obtaining continuous wave video images,the left and right camera images are matched with the semi-global stereo matching algorithm(SGBM)of the OpenCV library to obtain the disparity map,and then according to the principle of binocular visual distance measurement to obtain the three-dimensional coordinate value,and to reconstruct the three-dimensional coordinate.Secondly,After obtaining the world coordinates of a three-dimensional space point on the sea surface,use the RANSAC method to calculate and obtain the average water surface equation,and then use the distance formula from the three-dimensional space point to the three-dimensional plane to calculate the height of any point on the water surface relative to the average water surfa ce,which is the elevation H information of waves.For the image video formed by continuous shooting of the sea surface with the calibrated and corrected camera,a frame of image is intercepted at regular intervals and a fixed position pixel array is selected on the water surface image,for each pixel in time interval t and pixel intensity of x axis and y axis to form the pixels respectively sequence,and then perform one-dimensional discrete Fourier transform on the pixel time sequence to obtain the interlaced spectrum and phase spectrum,and estimate the time delay ?0 based on the interlaced spectrum and phase spectrum,and finally use the vertical and oblique time delays of the pixels on the ocean wave image to estimate the information of the wave velocity C and the wave direction angle a.Thirdly,the 3D coordinate reconstruction and height solving algorithm adopted in this paper are used to measure the height of five objects,after analyzing the experimental data,the relative error of the measured height of different objects is within the range of 0.3%-7.3%,and the measurement accuracy is high,which proves that the algorithm used in this subject is feasible;the wave direction angle of the sea wave is simulated based on the JONSWAP wave spectrum model.The wave direction angle calculated by the wave direction angle calculation algorithm used in this paper is compared and analyzed with the known wave direction angle of the wave model.The relative error of the measurement is between 0.76%-4.97%,and the experimental data has high accuracy.Because the principle of solving the wave velocity and the wave direction angle is the same,it proves that the algorithm is feasible.Finally,this project respectively carried out the measurement experiment of wave height,wave velocity C and wave direction angle a in the two waters of Songhua River and Majiagou.The wave height measurement experiments in Songhua river and Majiagou water area of relative standard deviation(RSD(H))is within respectively 2.5%-7.9%and 3.7%-12.5%,the measurement accuracy is high.The relative standard deviations(RSD(C)and RSD(a))of the measurement experiment of wave speed and wave direction angle in the Songhua River water area are respectively in the range of 4.7%-5.8%and 5.5%-16.9%,the relative standard deviations(RSD(C)and RSD(a))in the water area of Majiagou are within respectively 5.5%-16.9%and 10.5%-13.1%,the measurement precision is relatively high.