Compare points with a design surface

Import a LandXML TIN and see cut, fill or on grade for every collected point, with a tolerance you set.

On this page

A design surface is the shape the ground is supposed to end up. Import one from a LandXML file, and Tools → Design surfaces compares every point you've collected with it. Each point is reported as Cut, Fill or On grade.

Before you start

  • A LandXML file that contains a surface as a TIN (triangles), from your design or CAD software.
  • The project's coordinate system set to the zone the design was drawn in.
  • Collected points with a measured height. Points without a height can't be compared.

Import a surface

  1. Go to Tools → Import points & routes and choose the LandXML file.
  2. The import preview lists the file's points, then a Design surfaces section with each surface's name and its number of triangles.
  3. If the preview shows Northing/easting are in or Heights are measured in, check them: the surfaces are converted to metres using the same choices as the points.
  4. Tap Import as design features.

Surfaces are stored with the project, but they aren't assets. They don't appear on the map or in the list; they're a reference the job is measured against.

See cut and fill

  1. Go to Tools → Design surfaces (the row reads Cut and fill).
  2. Each surface shows:
    • its name and number of triangles,
    • its Elevation range,
    • the file it came From,
    • its Zone, if the file named one. If not, an orange note says its coordinates are assumed to be in the project's zone.
  3. Tap the surface name to open its cut and fill report.

The report compares every collected point, not design points, lines or areas:

Section What it shows
Header A summary, for example 4 cut · 7 fill · 12 on grade · 2 off the surface.
On grade within The tolerance, in your display unit. Leave it empty to use 0.030 m (the placeholder shows it in your unit).
Worst The point furthest from the design, either way.
All points Every point with a verdict, such as Cut 0.25 m or Fill 0.08 m.
Off the surface Points outside the surface. There's no design elevation to compare them with, and the app doesn't extend the nearest triangle to invent one.
No measured height Points without an elevation.

Tips and limits

  • Cut and fill use orthometric elevations. Set your vertical datum, and make sure the receiver's geoid matches the design's vertical datum. A GEOID18 design compared with EGM96 heights will be off by the difference between the models.
  • The tolerance and the results use the same unit, so a verdict judged in one unit is never reported in another.
  • Surfaces are stored in the grid coordinates they were imported with. If you change the project's coordinate system afterwards, delete and re-import the surface.
  • To remove a surface, tap Delete surface, then Delete. The file it came from isn't touched.