Terrain flattening and converting gamma0 to sigma0

[ABraun]

I am not sure myself but this is part of the answer:

Terrain Flattening Black Areas

The problem occurs with the ‘non-regrid’ method. We plan to deprecate this method in favour of re-gridding. Currently however, the regrid method forces you to multilook excessively to the point that both range and azimuth resolution are less than the DEM.