Subtract Grid

Use the Subtract one Grid from Another dialog (GRIDSUB GX) to subtract one grid from another.

Subtract one Grid from Another dialog options

First input grid:

First input grid (.grd file)

Script Parameter: GRIDSUB.IN1

Second input grid to subtract from first:

Second grid to subtract from first (.grd file)

Script Parameter: GRIDSUB.IN2

Output difference grid:

Output difference grid (.grd file)

Script Parameter: GRIDSUB.OUT

Application Notes

Subtraction of the grids occurs grid point by grid point.

Following are examples where adding or subtracting grids can be useful:

A regional (smoothed) grid may be subtracted from the original grid to produce a residual.
In magnetic surveys, the IGRF (International Geomagnetic Reference Field) may be calculated at a small number of points within an area and gridded separately. This grid may then be subtracted from the total magnetic field to effectively remove the IGRF.

If second input grid does not match the first in coordinate system, grid size or cell size, it will be sampled to match the first grid and the result grid will be spatially equivalent to the first grid.