Native DEM posting vs the 5 m output grid

Two different numbers — source DEM resolution and analysis grid spacing — are often confused. Both matter for honest screening.

Region-routed DEM sources

TerrainIQ does not use one global dataset everywhere. It routes by location — see Regional DEM routing for EEA-10, USGS 3DEP, FABDEM, and GLO-30 fallback. Native posting is typically ~10 m (Europe, USA where available) or ~30 m (global FABDEM / GLO-30).

What GLO-30 provides (fallback)

Copernicus DEM GLO-30 is a global elevation model with roughly 30 m horizontal posting at the equator. It is the standard free global dataset for early terrain review before LiDAR or RTK survey.

Vertical accuracy in open terrain is typically on the order of ±1–3 m RMSE versus higher-quality reference data. Vegetation, buildings, and voids can bias local slopes.

What the 5 m grid means in TerrainIQ

TerrainIQ's default 5 m output grid is the spacing between analysis points inside your site boundary. Slopes, terrain statistics, contour maps, and CAD exports are computed on this grid.

Resampling to 5 m makes contours and DXF linework smoother for layout review. It does not mean elevation was measured every 5 m. Think of finer graph paper drawn over the same ~10–30 m source photograph.

Common mistake: Assuming a 5 m export resolves ditches, berms, or field rows smaller than the native DEM posting (~10–30 m). Those features may not appear until survey-grade data.

When to coarsen the grid

Very large boundaries can produce millions of grid points. TerrainIQ offers optional auto-coarsening for speed on huge sites. For layout work on typical utility-scale parcels, keep the default 5 m unless runtime is prohibitive.

Next steps