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For other meanings of "Ground truth", see Ground truth.

GroundTruth software generates maps for Garmin GPS units using OpenStreetMap data and NASA's SRTM digital elevation model. It's being maintained by User:Breki.

Who is GroundTruth for?

  • OSM mappers who use Garmin units for mapping and who want their maps to contain as much useful information as possible.
  • Non-OSM users who want to have free (and often better quality) maps of the world.

Main features

  • Support for custom line and area styles - you specify how the feature should look like
  • Support for custom icons for POI
  • Map rules can be shared among mappers by publishing them on this Wiki.
  • Automatic generation of TYP files
  • Generating relief contours using NASA's SRTM data
    • Generating OSM files with contours (a successor to Srtm2Osm)
  • Downloading of OSM vector data
  • Support for additional map features (like map transparency) available through cgpsmapper
  • Conversion of national characters into the ones supported by Garmin units
  • Generation of Mapsource preview files
  • Registration of generated maps into Mapsource
  • Automatic uploading of generated maps onto a GPS unit
  • Command-line interface


You can download the latest package (or older ones) from You need to have Microsoft .NET 3.5 SP1 (available here) installed on your computer in order to run GroundTruth. If the link above is unavailable you can download the program from (the latest version is of 13-Feb-2013)

How to use

For a brief introduction please visit GroundTruth For Dummies.

For detailed instructions and FAQ please visit GroundTruth Manual.

See also