Impulse responses

Figure shows the effective migration operator ``impulse responses'' to standard and anti-aliased migrations. The responses are the result of migrating 10 adjacent traces with the two different methods to examine the effects of migration operator spatial aliasing. The ``standard'' response incorporates the effect of a $\cos^2\theta$ obliquity dip filter and a 45 degree migration aperture weighting to partially combat spatial aliasing. This eliminates near-vertical steep dip aliasing, but leaves a fair amount of spatially aliased speckling within the aperture cone. The ``anti-aliased'' response combines the standard response with the local lowpass anti-aliasing triangle filtering, including the inverse triangle height weighting. Note that most of the aliasing has been suppressed, resulting in smooth and coherent migration ellipses. At steep dips the anti-aliased operator is of lower frequency in comparison to the standard response, as anticipated, but of similar bandwidth near the horizontal (zero-dip) portions of the operator.

 

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Figure 4 Effective migration operator ``impulse responses'' to standard, and anti-aliased migrations. The ``standard'' response has a $\cos^2\theta$ dip filter and a 45 degree aperture weighting cone. The anti-aliased response is identical to the standard response except that it also has the anti-aliasing triangle filters applied.