The Isosurface module allows you to calculate the volume of the enclosed areas of the Isosurface. To calculate the volume for an Isosurface, the Compute volume checkbox needs to be checked on the General tab of the Property Manager. Volume calculations are generated for both inside the Isosurface and outside the Isosurface; the total of the two calculations should be the total volume for the area.
Volume calculations are generated from all voxels either partially or fully included in the Isosurface. A voxel is fully contained if all of the eight corner lattice points have a component value greater than or equal to the Isovalue. A voxel is partially contained if one or more corner lattice points have a component value greater than or equal to the Isovalue. The total Volume >= isovalue is the sum of the individual volumes from these voxels. Results are provided in cubic units based on the units of the input grid file. To make volumetric sense, the X, Y, and Z units should be the same.
Updated October 28, 2015