Data infill

The input data was first bandpass-filtered to remove the DC component and to limit the high frequencies to 32 Hz, and subsampled to 16 ms. It was then infilled with null traces in both offset dimensions, padded to add negative inline offsets (to allow room for the multiples after migration), padded to extend the crossline aperture, and sorted into a five dimensional regular cube of time, offsets and CMP coordinates.