VolumeCalculator

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This page contains a Custom Transformer created by an fmepedia user.   See the attached files list at the foot of this page for the zip file containing this custom transformer.

Created by: Dave Campanas

The VolumeCalculator calculates the volume under a TIN and can be used to determine the amount of material added or removed from an area over time.

The transformer takes the standard TIN inputs of breaklines, 3D lines and points, as well as the boundary feature. This boundary feature allows you to ensure that the area whose volume is being measured remains consistent between the time periods. The boundary is draped over the full TIN, used to clip the input data, then again as the bounding breakline of the volume calculation TIN. For this reason, the boundary should fall completely within the input TIN data. The transformer also requires the Base Elevation parameter be set, which will be the elevation from which the volume of each triangle is measured.

The DEM:

The boundary draped on the full TIN:

The bounded TIN:

The total volume is summed from the volumes under each triangle within the boundary polygon, based on its height above the Base Elevation parameter. The volume is output as the attribute Total_Volume on the boundary polygon.

There are two parts to the volume calculation:

The first calculates the volume of the prism formed by the 2D area of the triangle multiplied by the distance between the lowest point of the triangle and the Base Elevation.

The second calculates the volume of the tetrahedron formed by joining the sloped triangle to its 2D base, using base area * height of tetrahedron / 3.

These two values are summed for each triangle and then all triangles are summed to get the total volume.