In this section, we propose the group sparse BPDN-based imaging approach for polarimetric TWRI system by combining the SPGL1 algorithm and NUFFT
technique to reduce the computer memory requirement and improve the computational efficiency and the imaging performance.
A 2D NUFFT
of NER (Non-Equispaced Results) type is adopted for the computation of the analytical functional gradient of the relevant cost functional to be minimized during the synthesis process.
Furthermore, to improve computational efficiency, a fast and accurate NUFFT
is adopted to calculate the forward scatter field.
Zhang, "Improved 3-D GPR detection by nufft
combined with MPD method, " Progress In Electromagnetics Research, Vol.
Thanks to the ideas of [16, 21], and , we propose a new hybrid approach based on nonuniform Fourier transform (NUFFT
) and the global optimization to optimize the sidelobe level suppression, the null control and antenna layout.
So the DMNUFFT algorithm is proposed with the DM and NUFFT
. The process of the DMNUFFT algorithm can be summarized as follows.
Here, the NUFFT
approach is used to accurately evaluate the integrals within the braces.
The NUFFT-based iterative methods that combine the CG algorithm with NUFFT
operations have been used in MRI , modern tomographic systems , and synthetic aperture imaging radiometers .
Regarding the radiation operator for the APRPOS, NUFFT
routines have been adopted to cope with the irregular spacing, see .
In Section 3, the backprojection algorithm is described by paying particular attention to the FFT + interpolation stage and by discussing how the latter can be implemented by a Non Equispaced Results (NER) NUFFT
The comparison of the computational time between the interpolation-FFT and NUFFT
are also shown.
This method adopts a triangular mesh to conform with the arbitrary shape of the discontinuity boundary, the Gaussian quadrature to increase the accuracy, and 2D nonuniform fast Fourier transform (NUFFT
) [18-21] to provide a computational complexity comparable with the traditional FFT algorithm.