Setting up w-projection

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5.3.18.2 Setting up w-projection

The w-projection mode is controlled using wprojplanes sub-parameter, e.g.

gridmode            = ’widefield’       #  The kind gridding kernel to be used for FFT-based transforms
     wprojplanes    =         64        #  Number of w-projection planes for convolution
     facets         =          1        #  Number of facets along each axis (main image only)

will construct 64 w-projection planes.

A reasonable value for wprojplanes is equal to n_w = B_max(inkλ) ×imagewidth(inarcmin²)∕600, with a minimum value of n_w = 16. The w-projection algorithm is much faster than using faceting, but it does consume a lot of memory. On most 32-bit machines with 1 or 2 Mbytes of memory, images larger than about 4000 × 4000 cannot be made.

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