Naming and Referencing Masks

A mask file is similar to a grid. It is used to store inside/outside information for a polygon. That is, which grid cells are inside the polygon and which outside. Polygons are used to delineate active sections of the grid (that is, areas of interest).

The format of the standard mask file name is:

			
   <proj><horizon>.msk

or

			
   <proj>.msk

For example:

abch.msk abc.msk

Mask files can be referenced in abbreviated form by using the letters msk. This refers to the mask for the current horizon, and if that does not exist, the mask for the default project. A specific horizon mask can be referenced by specifying the mask name in full.

When mask files are referenced in an expression, they are treated as grids. The grid values are the fractions associated with the mask cells. The grid masks flag is zero for all areas where the fractions are 0 (zero), and elsewhere, 1 (one). See also the Mask () Function.

The mask file for an area can be multiplied by a thickness grid to give a grid volume of material per cell. The Area field on the Mask panel (see Mask option under Model) can then be used to get an estimate of total volume.