SURFACEVOLUME — Earthwork volume

Computes cut and fill volumes between two surfaces or between a surface and an elevation.

• Command: SURFACEVOLUME · Global name: _SURFACEVOLUME · Alias: VOLUMES, CUTFILL
• Ribbon: Topography › Analysis

Computes cut and fill volumes between the terrain surface and a design surface, or between the terrain and a reference elevation, inside an optional boundary. It draws the results table as a TABLE, the cut and fill map with its legend and, if asked, saves the report as CSV.

Usage

1. Enter SURFACEVOLUME (CUBICACION) or click Earthwork volume on the Survey tab, Analysis panel.

Select the terrain surface (TIN):

2. Select the terrain surface (a SURFACE mesh).

Select the design surface or [Elevation]:

3. Select the design surface, or enter E to compare with an elevation.

Reference elevation:

4. With Elevation: give the reference elevation (horizontal plane).

Select the boundary (closed polyline) or [None] <None>:

5. Select a closed polyline that bounds the area, or press Enter to compute wherever both surfaces overlap.

Enter an option [Method/MAp/Csv] or press Enter to compute <…>:

6. The Earthwork volume dialog opens: method, map and CSV. Click OK (or press Enter on the command line).

Specify the table insertion point:

7. Specify where the results table goes.

Options

• Method (M): Prisms (default) or Grid, with the cell size.
• Map (MA): draw the cut and fill map or not (yes by default).
• Csv (C): file where the report (item, value and unit) is saved. With FILEDIA=1 it is chosen with the Windows dialog.

Results

• Cut: volume where the terrain is above the design (to be excavated). Fill: where it is below (to be filled).
• Net = cut − fill: positive when there is surplus earth.
• Areas in cut, in fill and the total compared, and balance = fill / cut, in %.
• The table goes on layer CUB_INFORME; the map and its legend on CUB_CORTE_RELLENO, in three shades of blue (fill) and three of red (cut) by depth.

Accuracy of the methods

• Prisms: overlays both triangulations. Each terrain triangle is clipped with each design triangle (and with the boundary); in each piece both surfaces are planar, the elevation difference is linear and it is split along its zero line. The volume on each side is its area times the difference at its centroid. It is exact for triangulated surfaces, with no error but rounding: in the test cases (pyramid, prism, sloped plane against an elevation, L-shaped boundary) the measured error is below 10⁻⁹, far below the required 0.01 %.
• Grid: adds difference × cell area at the center of each cell. It is approximate: it errs in the cells that cross the boundary, the triangle edges or the zero line. The error decreases with the cell size (in the test pyramid, below 0.1 % with 5 cm cells); it is useful as a cross-check and for very large surfaces.

See also

SURFACE · SURFACEANALYSIS · PROFILEVIEW · TABLE