The map of the Dolomites

A relief computed from real terrain elevation, the forest as seen from the satellite, and four hundred and fifty-nine places on true coordinates. Twenty groups: pick one to go inside it, down to the trails.

How it is built, and why you can trust it

The base is computed, not photographed: a terrain model with twenty-six-metre cells, lit from the north-west, with elevation bands running from the green of the valley floors to the pale tone of the high pastures. Where OpenStreetMap marks bare rock the colour turns limestone grey, and the groups stand apart at once. Rivers, lakes, roads and provincial boundaries come from there too. We tried a satellite photo as the base and dropped it: under the forest the valleys turn into one dark mass and the shape of the mountain disappears.

Forest and meadows come instead from ESA WorldCover, classified from Sentinel satellite imagery in ten-metre cells, so the woodland ends where it really ends, at the tree line. Glaciers do not. WorldCover reads a quarter of the Sella plateau as snow, and the Sella is pale rock, so we take glaciers only from their OpenStreetMap outlines: Marmolada, Pale di San Martino, Brenta, Antelao, Popera.

Inside a group the scale drops to about ten metres per pixel and the map becomes a hiking map: trees drawn one by one, trails as dashed red lines with tighter dashes for via ferratas, forest roads in brown, streams, scree, contour lines every hundred metres, villages house by house. Of the lifts, only those that carry people uphill are drawn: with the drag lifts in, the ski areas turned into a spider's web.

Every place has its own coordinates, not guessed from the valley, and in the panel it carries the same number as its marker. We compared them with Wikipedia on nine well-known spots: eight agree within eight hundred metres, and the one large gap is the Pordoi pass, where Wikipedia is the one that is wrong. Villages link to their page only when the name matches exactly, thirty-seven out of forty-one: approximate matching moved the Pale di San Martino plateau to San Martino in Badia, forty kilometres away.

The six outlines gather the twenty groups. Five follow the subsections of the SOIUSA classification, the sixth is the Brenta Dolomites, west of the Adige. They are not drawn by hand: each starts from the rock and the peaks of its groups. The names sit on their real summits as well, and where the peaks are missing from the data the name does not appear: Sciliar, Schiara, Vette Feltrine and the Friulian Dolomites stay unlabelled.

343 peaks and 20 groups, and no mark was drawn by hand: everything you see is data.