Cylindrical SAR imaging Based on a Concentric-square-grid Interpolation Method
Cylindrical millimeter-wave Synthetic Aperture Radar(CSAR)is one of the important technologies in the field of close-range non-contact imaging.High-resolution imaging algorithms based on Fourier transform theory require Two-Dimensional(2D)interpolation to eliminate the non-uniformity of wavenumber domain data in both the azimuth and distance dimensions.However,these two dimensions exhibit a high degree of coupling,in the form of a concentric-circle shaped filling in the wavenumber domain.This results in a high temporal complexity of the traditional interpolation method based on a 2D point-by-point traversal,leading to a low efficiency of the imaging algorithm.Therefore,the interpolation decomposition method of concentric square mesh is proposed by deriving the CSAR imaging algorithm based on the analytical solution.Through the zero padding operation,the radial 1D interpolation,and partition,the strong coupling of the azimuth dimension and distance dimension in the wavenumber domain would be eliminated.The uniform resampling of the 2D non-uniform wavenumber domain is achieved by two independent 1D interpolations with respect to two non-overlapping partitions.It yields the expected concentric-square-belt filling shape of the wavenumber domain.Experimental results demonstrate that the proposed method can effectively reduce the time complexity of the straightforward 2D interpolation and increase the efficiency of the imaging algorithm.And the interpolation processing speed of the proposed algorithm is increased by 7 times compared with the traditional algorithm,which is consistent with the theoretical analysis of the algorithm complexity.
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