The left side of Figure 2 shows the areal coverage of the two Gulf of Mexico datasets, and their 34 difference in azimuth. The 1979 survey covers a larger area, but there is a significant overlap.
The right side of Figure 2 shows a close-up of the bin-centers in part of the survey. The 1979 survey was shot and processed with bin-spacings of 82.5 ft (in-line), and 247 ft (cross-line); whereas the 1991 survey has 41 ft bin spacings in both the in-line and cross-line directions.
To compare the two surveys, the first step is to realign them both onto a common grid. In this case, we applied a spatial anti-aliasing filter in the (kx,ky) domain, and regridded the 1991 survey onto the 1979 grid. Since the 1991 survey was spatially-sampled so much more finely than the 1979 survey, a linear interpolation algorithm was used for the regridding, without causing artifacts.