Add elevation

duckosm elevation adds the ground height to every node of a finished build, in place. Needs pip install "duckosm[elevation]".

duckosm elevation monaco.duckdb

  source=auto → copernicus (bbox 7.41, 43.73, 7.44, 43.75)
  [cycling] 4151 nodes sampled (0 nodata/fill) -> ele
  [driving] 1719 nodes sampled (0 nodata/fill) -> ele
  [walking] 4116 nodes sampled (0 nodata/fill) -> ele
elevation added from Copernicus GLO-30 — 9986 nodes (0 nodata/fill) across 3 mode(s) -> ele

It adds:

• nodes.ele: the height at each node, in metres;
• edges.z_from, edges.z_to: the height at each edge's two ends;
• a row in main.elevation_metadata saying where the heights came from (source, resolution, vertical datum, licence).

The MATSim, OpenDRIVE, GIS and GMNS exports then include the heights (GMNS: node.z_coord, link.grade).

Where the heights come from

With no options it picks a free global elevation model for your area and streams just the part it needs: Copernicus GLO-30 (30 m, worldwide, no account). Inside Europe it uses EU-DTM instead when you set an OpenTopography key in OPENTOPOGRAPHY_API_KEY. For better accuracy, point it at your own file, e.g. a national 1 m model:

duckosm elevation monaco.duckdb --dem my_dtm.tif          # any GDAL raster

Option	Does	Default
--dem FILE	use this elevation file (GeoTIFF, VRT, … any format GDAL reads)
--source	auto, copernicus, or eudtm (needs the key)	auto
-m MODE	only this mode; repeat for several	every mode
--nodata-fill	height written where the model has no value	0
--suffix dsm	store as a second surface (ele_dsm, z_from_dsm, …) instead of replacing

Where to get elevation data, and how the sources compare: Elevation sources.

What the heights mean

The height is the surface at the node's position, not the road itself:

• A tunnel gets the height of the ground above it, and a bridge the ground below.
• Copernicus is a surface model: it includes buildings and trees, at 30 m resolution. In a dense city, short streets between buildings can look steep. A bare-earth model (EU-DTM, or a national one) gives better road grades.

So leave tunnels and bridges out when you look at gradients:

SELECT name, round(z_from) AS z_from, round(z_to) AS z_to, round(length_m) AS length_m,
       round(100 * (z_to - z_from) / length_m, 1) AS grade_pct
FROM driving.edges
WHERE length_m > 100 AND name IS NOT NULL AND tunnel IS NULL AND bridge IS NULL
ORDER BY abs(z_to - z_from) / length_m DESC LIMIT 5;

name	z_from	z_to	length_m	grade_pct
Boulevard de Belgique	86.0	111.0	110.0	22.5
Boulevard de Belgique	111.0	86.0	110.0	-22.5
Boulevard du Jardin Exotique	117.0	97.0	123.0	-16.5
Boulevard du Jardin Exotique	97.0	117.0	123.0	16.5
Avenue de La Quarantaine	32.0	8.0	144.0	-16.1

With Copernicus, the tunnels of Monaco would top this list: Tunnel Albert II "falls" from 336 m to 32 m, the height of the hill above it.