Astronomers have historically used convolution gridding to put visibility samples on to a regular space grid so that a FFT can be used to generate the image; the analytic Fourier transform to do this would just take too long. In other areas of imaging science non-equispaced FFT algorithms are now being use to solve this generic problem. A number of institutes (Berkeley, Stanford, NYU, Michigan, Chemnitz) are offering their algorithms for download and test. How effective can these be for aperture synthesis? Does anyone have any recommendations about who might offer the best algorithms for non-equispaced FFT’s?
many thanks, Neil
Nope I have not used any : check for performance comparison
https://www-user.tu-chemnitz.de/~potts/nfft/download.php
Although , hexagonal sampling grids have not worked as against the standard rectangular for limited bandwidth !!!
Again this spacing cannot be randomly taken too (at least so I have understood theoretically )
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