The ideal acquisition pattern for plane-wave synthesis is a fixed-split spread with wide aperture (Figure ). With this acquisition, every receiver will record reflected wave fields caused by every source wave field. In practice, however, a moving one-side spread (Figure ) is the typical acquisition pattern in marine surveys.
The forward model in equation () implicitly assumes an infinite aperture experiment. In order to model correctly, we need to incorporate the aperture effect as follows:
In the case of the one-sided spread acquisition, we can expand the acquisition area using the principle of reciprocity, which states that if we exchange the source and receiver positions, we would record the same seismic trace at the source position. The acquisition pattern is expanded using the principle of reciprocity as depicted in Figure .
However, Figure shows that we still have some missing regions in near and far offset after the acquisition expansion that uses the principle of reciprocity. The missing part of the far-offset limits the angle coverage of the reflectivity information. Since the maximum incidence angle of the source wave field generally decreases as the depth of reflector increases (Figure ), we can avoid the effects of cable length by synthesizing different incidence angle ranges at every depth level.
The effects of the missing part of the near offset are not as easily avoided as those of the missing part of the far offset, because the effect of missing near-offset traces differ in terms of missing reflection angle ranges from depth to depth and are located around the normal incidence angle to reflectors (Figure ). In order to obtain a good image in every constant angle illumination, we need to interpolate the missing near offset traces.