Isolation Evaluation Method for Fully Polarized SAR Based on Distributed Targets

Abstract

The invention provides a method for evaluating full-polarized SAR isolation degree based on distributed targets. The method obtains a ground feature, reversely adds crosstalk to the actually measured scattering matrix of the selected ground feature, obtains the estimated value of the SAR crosstalk by using a correlation coefficient between channels, so as to reflect the isolation degree of the polarized channel of the polarized SAR. The method mainly solves the estimation of the polarization isolation degree in the full-polarized SAR quality evaluation, and comprises main steps of: selecting a ground feature, dividing the actually measured scattering matrix of the selected ground feature, namely data M to be evaluated, into N data blocks MN with the same size; reversely adding crosstalk [delta] to the data blocks MN, and computing the correlation coefficients [rho]HHHV, [rho] HHVH, [rho]VVHV, [rho]VVVH between the co-polarized channel and the cross-polarized channel under different [rho]; acquiring the added crosstalk values which minimize the correlation coefficients [rho]HHHV, [rho] HHVH, [rho]VVHV, [rho]VVVH for each data block; subjecting the 4N crosstalk values to statistical averaging to obtain the crosstalk estimated value, and taking the negative value of the crosstalk estimated value as the polarized channel isolation degree.

Description

technical field [0001] The invention relates to the field of SAR signal processing, in particular to a method for evaluating the isolation degree of fully polarized SAR based on distributed targets. Background technique [0002] Synthetic Aperture Radar (SAR) has the advantages of all-day, all-weather and high-resolution imaging, and has a wide range of applications in terrain mapping, ocean monitoring, agricultural and forestry crop assessment, disaster relief and other fields. Full polarization SAR has all the characteristics of SAR, and can also provide richer target information, providing a wider data source for analysis and extraction of target characteristics. Good data quality is the basis for the application of polarimetric SAR, and an effective evaluation index of polarimetric SAR image quality is a necessary condition for mastering the quality of polarimetric SAR data and measuring the effect of data processing. System optimization provides guidance basis. [000...

AI Technical Summary

Problems solved by technology

The crosstalk calibration algorithm using distributed targets can calculate the crosstalk value more accurately, but all of them have strict requirements on the calibration ground objects, and generally require them to meet the backscattering reciprocity or (and) co-polarization and cross-polarization There is no correlation between channels, and most of the ground objects in polarized images are often complex and uneven, which cannot strictly meet the calibration requirements

Therefore, the above-mentioned crosstalk calibration algorithm is not suitable for the quality evaluation of polarimetric SAR. There is an urgent need for a crosstalk estimation method that can be used in general polarimetric images without relying on facilities such as calibration fields and scalers. Polarization isolation, evaluate the data quality of polarimetric SAR, assist the processing of the actual system and the application of polarimetric SAR

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