Uncalibrated airborne SAR image sea peak suppression method based on optimal polarization ratio

Abstract

The invention discloses an uncalibrated airborne SAR image sea peak suppression method based on an optimal polarization ratio. The method comprises the following steps: generating and storing a single-view complex image according to original data of a region of interest received by an SAR; selecting the single-view complex image ocean background sub-blocks, and performing azimuth multi-view processing to obtain dual-polarization intensity data of the background sub-blocks; processing the background sub-blocks, traversing the theoretical value of the polarization ratio, and calculating and obtaining a plurality of polarization difference images in combination with the dual polarization intensity data of the background sub-blocks; calculating a normalized mean square error between each polarization difference image and the HH polarization SAR image, taking a polarization ratio theoretical value corresponding to the maximum normalized mean square error, and defining the polarization ratiotheoretical value as an optimal polarization ratio; and correcting the HH polarization intensity according to the ratio of the optimal polarization ratio to the mean value of the region-of-interest data, and calculating and obtaining a polarization difference image, thereby achieving sea peak suppression.

Description

technical field [0001] The invention belongs to the field of synthetic aperture radar image processing, and in particular relates to a method for suppressing sea spikes in unscaled airborne SAR images based on optimal polarization ratio. Background technique [0002] Synthetic Aperture Radar (SAR) is an information acquisition technology that uses electromagnetic waves in the microwave spectrum as the detection carrier and uses synthetic apertures to achieve high-precision two-dimensional imaging of observation objects. Compared with traditional optical imaging, SAR has the advantages of all-day, all-weather, high resolution and wide observation range. Ocean observation is one of the important application directions of SAR. SAR can detect various ocean phenomena such as waves, internal waves, eddies, fronts, etc., can invert vector information such as wind field and flow field, and can identify oil films and ships. Classification. With the improvement of high-resolution re...

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Problems solved by technology

Considering the scattering characteristics of the sea spikes, although the polarization difference can effectively suppress the sea spikes, it brings difficulties to the calculation of the polarization difference for the airborne data that is not radiometrically calibrated

[0006] Most of the existing sea peak suppression methods start from the transform domain, only considering the geometric characteristics of sea peaks, and suppress sea peaks by filtering methods. These methods will also affect the texture of other ocean phenomena while suppressing sea peaks. Loss; the new idea is to suppress the sea spikes according to the polarization scattering characteristics of the sea surface. Although the polarization difference can effectively suppress the sea spikes, if the airborne SAR data is not radiated, the polarization difference will not be calculated.

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