Research On Wave Height Inversion Based On Dual Rader Image Mosaic

With the rapid development of marine detection technology,using X-band navigation radar on the ocean to conduct a large area measurement and real-time monitoring is becoming a research hotspot of ocean remote sensing in recent years.It also has a greatly important guiding significance for the security of the port and the sea operations by using the collected radar image to retrieve various sea information,such as the significant wave height,direction of wave,period of wave.Relying on the native defense scientific research project of "the ocean wave inversion technology by shipborne X-band radar",this paper studies the method of image mosaic and retrieving the significant wave height from the navigation radar image by using a large number of X-band radar image data.Because the collected images of sea clutter contain noise,image preprocessing is the basis for image mosaic and inversion of effective wave height.In this paper,using the parameters of the radar image identify whether there is rainfall,remove the radar original image with rainfall.According to the correlation between sea clutter echo signals,the method of interference noise-spatial domain correlation method can preserve the original information of the radar image to the maximum while filtering the same-frequency interference noise.Finally,the image is fixed target elimination,material heading correction and motion compensation.When inverting wave parameters,the choice of data analysis area affects the accuracy of the wave height estimation.If there is a blind area or an occlusion area in the selected analysis area,the analysis area needs to be re-selected.A splicing method based on double radar image is proposed in this paper according to blind area problem.In order to solve the problem of image matching when the image brightness is inconsistent.In this paper,using the multinomial least square method and the adaptive piecewise least squares fitting of the curve of average radial radar echo and antenna distance,to design simulation experiment platform,proven by the experimental data which is proposed show that splicing method is superior to direct splicing method.The usual echo intensity in the crosswind direction of radar images is small,which may easily lead to the overestimation of the shaded area of the image,resulting in a decrease of the inversion accuracy of the sea wave parameters.Rune's method of dividing the shadow by a fixed step size will result in a large error in the shadow ratio calculation.Resulting in the estimated wave height is not allowed.In this paper,we propose a method that divides the data analysis area and adaptive shading ratio based on the feature of wind angle.The algorithm can automatically divide the shaded area into the best number of blocks and determine the best segmentation position,Increase shadow ratio accuracy.Using a large number of shaded thresholds for X-band marine radar imagery,which found that the shading threshold does not change under the same sea condition,but there is a large difference between the shaded thresholds of the shore and sea experiments.According to the data area divided by wind angle and the shadow ratio by adaptive method,the normalized steepness of different wind included angles is calculated by the Smith function,and the effective wave height is estimated by the weighted average of steepness coefficients.Finally,valid wave height relationship curve is gotten on the basis of different wind included angles.By comparing the data of wavex data between the effective wave height retrieved from the proposed algorithm and the effective wave height estimated by Rune,it can verify the accuracy of the proposed algorithm in improving the effective inversion wave height.