Files to use: TIF, DXF, CSV. Written for: Civil 3D 2025 help.
Steps
- Set the drawing's units to metres and its coordinate system to British National Grid (OSGB36) in Drawing Settings.
- Create an empty TIN surface (Prospector › Surfaces › Create Surface).
- Easiest: under the surface's Definition, right-click DEM Files › Add and choose the ground model GeoTIFF (Autodesk lists GeoTIFF among its DEM formats). Or add the contours from the DXF (Definition › Contours › Add) after attaching or copying them in.
- To use the spot levels as COGO points, import
spot_levels.csv with a comma-delimited Easting-Northing-Elevation format. The first line of the file is a header, so delete it first if your point file format doesn't skip it.
Good to know
- A LiDAR ground model is a dense grid. Check the surface's statistics against the report's lowest and highest levels.
Coordinates, units and heights
- Units are metres. Plan positions are real Ordnance Survey British National Grid coordinates (EPSG:27700), so a point at easting 324630, northing 639730 sits at exactly those coordinates in your drawing.
- Heights are metres above Ordnance Datum Newlyn, as in the LiDAR. Each contour line is drawn at its own height, and each spot level is a 3D point with a text label beside it.
- The layers are listed in SOURCE_AND_ACCURACY.txt, along with the survey date and the accuracy note. Keep it with the drawing.
Vendor help: Autodesk Civil 3D help: To Add DEM Files to a Surface. If your version's menus differ, follow the vendor's page.
Try it with a real sample first
Real public LiDAR for a small patch of ground at the edge of Peebles (Scottish Public Sector LiDAR Phase 3, 0.5 m). It's a sample area, not a real plot for sale. Free to download, no account needed.
Scottish Government LiDAR, tested to ±0.14 m typical on open ground (95% within ±0.28 m), shown with the date the survey was flown. Good for feasibility and early design; for setting out and detailed design, commission a measured survey. When you need a surveyor.
Other guides: AutoCAD · Revit · SketchUp · Vectorworks · QGIS
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