IGN maps, offline on your iPhone
For France, the IGN's topographic maps — above all the 1:25,000 série bleue / TOP 25 — are the reference: every sentier, refuge and rock band from the GR20 to the Vanoise. IGN's public geodata is open and free, and the paper sheets are sold at every good bookshop. Either way, NomadTracks turns the map you trust into a live offline layer with your position on it.
Where to get the maps
IGN publishes its maps and geodata through its official portals — Géoportail and its successor cartes.gouv.fr (which replaces Géoportail in 2026) — where the classic SCAN 25 topographic cartography can be viewed and IGN's open data downloaded free. Paper TOP 25 sheets remain available everywhere; for NomadTracks, a georeferenced GeoTIFF import aligns automatically, and a photographed or scanned paper sheet georeferences in-app with a few control points.
The 1:25,000 difference
French 1:25,000 sheets carry the full mountain treatment: named couloirs, springs, cabanes, precise trail alignments for the GR network. Off the marked sentiers — or on them, in Corsican fog — that detail is the difference between a plan and a guess. With control points set on summits or path junctions, a photographed sheet typically aligns to within a few meters, with the accuracy shown live.
Offline in the French mountains
The Écrins, the Pyrenees and half of Corsica have proudly little signal. Maps stored in NomadTracks work with the radio off, recording works everywhere GPS reaches, and the recorded track on IGN cartography is the cleanest tour documentation there is. No subscription, no account — the map is yours, the data stays yours.
NomadTracks is not affiliated with or endorsed by any mapping agency. Always check the agency's current licence terms for your intended use; the notes here are a good-faith summary as of June 2026.
FAQ
Are IGN maps free?
IGN's public geodata — including its topographic map layers — is open data, freely accessible through the official portals (Géoportail / cartes.gouv.fr). Paper TOP 25 sheets are sold normally; photographing a sheet you own for private navigation is personal use.
Which format works best in NomadTracks?
Georeferenced GeoTIFF imports align automatically. Plain images, scans or photographed paper sheets work via manual control points, with a live ± meter accuracy readout.
Does this work on the GR trails with no signal?
Yes — the imported map lives on your device and GPS needs no network, so navigation and recording work the whole way, from the GR10 to the GR20.