Grid Volume

Use the Grid and Image > Utilities > Grid Volume menu option (GRIDVOL GX) to calculate the volume of space defined by a grid surface—both above and below a reference base.

Grid Volume dialog options

Grid file	Select the input grid file (*.grd). Script Parameter: GRIDVOL.GRD
Reference base for volume calculation	Enter the reference base from which the volume is calculated. (Default: 0) Script Parameter: GRIDVOL.REFBASE
Multiplier to apply to volumes	Specify a multiplier to adjust the final volume for unit correction. (Default: 1) Script Parameter: GRIDVOL.MULT

Volume Report dialog options

Volume above reference base	Volume of the grid above REFBASE. (Output only) Script Parameter: GRIDVOL.ABOVE
Volume below reference base	Volume of the grid below REFBASE. (Output only) Script Parameter: GRIDVOL.BELOW
Difference	Difference between the above and below volumes. (Output only) Script Parameter: GRIDVOL.DIFF

Application Notes

The grid volume is calculated by summing the product of the grid area times the distance between each non-dummy grid point and the supplied reference base. If the grid contains elevations lower than the reference base, volumes will be reported for both the areas above and below that base, as illustrated in the diagram and explained below.

• GRIDVOL.ABOVE, GRIDVOL.BELOW, and GRIDVOL.DIFF are output-only values.

• Both GRIDVOL.ABOVE and GRIDVOL.BELOW are reported as positive values.

• GRIDVOL is useful for determining the volume of material defined by grid surfaces in topographic applications. Some geophysical applications also make use of volumes under anomalies to derive physical properties (e.g., gravity).

• The calculated volume of the grid is displayed as a floating-point number in the default output. This output can be piped to another application if needed.