SYNTHETIC DATA EXAMPLE

The program has been used to generate many figures appearing elsewhere in this report Bevc (1992); Black et al. (1992a,b). Figure 1 illustrates the advantage of the anti-aliasing concept.

The synthetic data are generated with the anti-aliasing turned on to simulate field arrays. The image is generated by running kfastaax() with anti=1 and then performing a causal half-order time derivative. The effect of simulating field arrays is that the input impulses are broadened. The point diffractors appear as hyperbolic trajectories with a $45^{\circ}$ phase shift on the wavelet.

The migrations are performed with (anti=1) and without (anti=0) anti-aliasing and are followed by an anticausal half-order time derivative. The aliased migration (lower right of Figure 1) exhibits systematic noise. The point diffractors have upturned artifacts which appear on adjacent traces as part of a smile-like feature. The flat event has a prominent precursor which looks like a layer above the actual event. Anti-aliasing removes the systematic noise and results in a much better image.

 

migalias
Figure 1 Top left is synthetic input. The top right synthetic data was made by setting the anti-alias parameter anti=1. The bottom figures are migrations with and without anti-alias. Bottom left has anti=1 and bottom right has anti=0.