Terrain data, accuracy and limits
Every model is built from elevation data: a grid of ground heights measured from space or from aircraft. It is impressive, but it is not perfect, so a model is a keepsake and not a survey.
The sources
- AWS Terrain Tiles. The default. It needs no key and has a detail of about 30 m. The data is older and no longer updated, so in Europe it is slightly smoother than Copernicus, and summits can sit about 15 m low.
- Copernicus GLO-30. Sharper, global, and needs a free OpenTopography key. It records the top of trees and buildings, not always bare ground.
- SRTM and NASADEM. Well-known datasets, covering 60° north to 56° south. They need a free key.
- ALOS World 3D. A global 30 m dataset. It needs a free key.
A free key comes from OpenTopography. You only need one if you want these sharper sources.
Why heights can differ
- Each height covers a square about 30 m wide, so a narrow summit or ridge is averaged out.
- Trees and buildings can raise the surface.
- Steep cliffs and deep valleys can be hard to measure, and some areas have gaps.
- Your GPS track may sit a little to one side of the true path.
Sea and lakes
TrekForge is made for routes on land. Water appears as a flat or roughly shaped surface, and seabed data is very coarse, so it does not suit dive or sailing routes.
Do not navigate with it
Models and the on-screen map are not for navigation, planning a route or anything else where safety depends on them.
Last checked 1 November 2026.