The steps to digitise a road comprise:

  1. Select from the draw menu Noise Source/Road
  2. Enter the road elevation (or if your DTM is very detailed ignore) otherwise prior to digitising any point edit to the appropriate elevation;  (to assist you can turn on display options to display ground elevations)
  3. Click the start digitising button (the pencil icon in the tool bar)
  4. Go to the start of the road and mouse left-click to start digitising;
  5. Move to the end of the road segment, mouse left-click to end the road segment and this brings up the CoRTN entry dialog.  Enter the properties for this road segment.
  6. Repeat step 5 until end of road and press the stop digitising button
  7. If there is a high quality DTM then select the on-ground option (under the calculations menu item)

Try turning on and off the “on-ground” option.  PEN3D will optionally calculate the best height for each end of the road segment based on the underlying terrain model when turning off the “on-ground” option.  The calculations are fractionally quicker with on-ground turned off, However, with a high-quality DTM a better representation of the road is usually achieved using the on-ground model.

Click image to see an animated GIF of the process


  • PEN3D: Enter Road Segment
  • Skills Needed: Basic digitising with PEN3D