The flat layer model I constructed can be seen in the top right panel of Figure . It has the same dimensions as the migration result from the previous subsection, but is composed entirely of flat layers. I modeled the data that would be produced from these flat layers with the adjoint of the migration scheme described in the previous subsection, using the velocity model from Figure . I then migrated that data to get the weighting operator defined in equation (2). The lower panel of Figure shows this weighting operator.
The weighting operator in Figure is displayed as a flattened cube. The front of the cube shows a common ray parameter slice in which the high values of the weighting operator can be seen in the shadow zones. The top of the cube is shown above the common ray parameter slice and shows a depth slice. In this depth slice, we can see that the weighting operator indicates that the subsalt illumination along CRPs is becoming worse with larger ray parameters. The side of the cube shows a ray parameter gather taken from a CRP at the salt edge. This view shows how illumination varies along ray parameter and with depth. It also shows some vertical striping that I believe is caused by the way I took the smoothed analytic signal envelope. We must keep this in mind as we apply this weighting function to the image.