Difference Contours
This tech tip explains how to use difference contours to show cut and fill
Calculating the Volumes
In our example, we have 2 dtm surfaces. Surface 1 is the ground surface (grey) and surface 2 (blue) is the proposed terrace.
Change to Terrain Mode (Mode Menu › Terrain or via the Modes Toolbar)
Terrain Menu › DTM Grid Volumes › Ground/Design Difference
Select the correct surfaces and click OK to continue.
The Grid Details dialog appears, the user can accept the Grid interval or specify another interval. Once the new grid interval has been specified, click on the Preview button to view the new grid.
If the grid interval is too small, an error message will appear.
The next dialog that appears is the Double Surface Details dialog.
Click OK to continue
The site will be shaded during the calculation phase.
Once the calculations are complete, you can specify the amount of top soil striped and the compaction factor. Various factors can be used without re-running the calculatio
The results are shown in the output window (unless otherwise specified in the Output Manager) The Output Manager settings can be changed File Menu › Output Manager
Generating the Contours
Terrain Menu › DTM Contours
Specify the desired contour interval
Once the contours are generated, we will specify the colours for the different contours.
Settings Menu › Display Settings
Make sure Generated is selected, and the colours for Difference contour display are set to the desired colours.
Click OK to continue.
The project will now show the difference contours i.e. where there is cut and fill.
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