Abstract
Synthetic aperture imaging radiometers (SAIRs) are powerful passive microwave systems for high-resolution imaging by use of synthetic aperture technique. However, the ill-posed inverse problem for SAIRs makes it difficult to reconstruct the high-precision brightness temperature map. The traditional regularization methods add a unique penalty to all the frequency bands of the solution, which may cause the reconstructed result to be too smooth to retain certain features of the original brightness temperature map such as the edge information. In this paper, a multi-parameter regularization method is proposed to reconstruct SAIR brightness temperature distribution. Different from classical single-parameter regularization, the multi-parameter regularization adds multiple different penalties which can exhibit multi-scale characteristics of the original distribution. Multiple regularization parameters are selected by use of the simplified multi-dimensional generalized cross-validation method. The experimental results show that, compared with the conventional total variation, Tikhonov, and band-limited regularization methods, the multi-parameter regularization method can retain more detailed information and better improve the accuracy of the reconstructed brightness temperature distribution, and exhibit superior noise suppression, demonstrating the effectiveness and the robustness of the proposed method.
Highlights
Synthetic aperture imaging radiometers (SAIRs) are passive microwave sensors for high-resolution imaging
Different from conventional real aperture radiometers, SAIRs improve the spatial resolution by use of the synthetic aperture technique, which avoids the difficulties of mechanical scanning such as the bulky volume and weight caused by a real large-aperture antenna
In order to ascertain the effectiveness of the above multi-parameter regularization approach, numerical simulation experiments are carried out on the full polarization interferometric radiometer (FPIR) system [26]
Summary
Synthetic aperture imaging radiometers (SAIRs) are passive microwave sensors for high-resolution imaging. Different from conventional real aperture radiometers, SAIRs improve the spatial resolution by use of the synthetic aperture technique, which avoids the difficulties of mechanical scanning such as the bulky volume and weight caused by a real large-aperture antenna. The typical SAIR instruments that researchers have developed include electronically scanned thinned array radiometer (ESTAR) [4], microwave imaging radiometer with aperture synthesis (MIRAS) [5], geostationary synthetic thinned array radiometer (GeoSTAR) [6], and geostationary interferometric microwave sounder (GIMS) [7]. The reconstruction process from the visibility function to the brightness temperature image has been proved to be an ill-conditioned inverse problem [8]. The aim of regularization is to obtain a stable and unique solution by adding new restrictions or penalties on the inverse problem.
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