OpenStreetMap Standard
A general-purpose global basemap. Useful for roads, buildings, settlements and orientation.
OpenTopoMap
A global topographic map based on OpenStreetMap data and elevation models. Useful when terrain, paths and relief help identify historical features.
IGN orthophotography + cadastral parcels
High-value reference layers for building footprints, roads and parcel geometry in France.
IGN LiDAR HD
DTM, DSM and height-model hillshades reveal terrain, above-ground features and relative heights. They are especially useful for comparing aerial imagery with subtle topographic traces.
BRGM / InfoTerre geological maps
GeoCalque includes the harmonized 1:50,000 geological map and a simplified lithology overview, available as basemaps or transparent layers.
Dominant soil map — GIS Sol / INRAE
The 1:250,000 pedological reference provides regional soil context. It should not be interpreted as a parcel-scale soil survey.
1950–1965 aerial imagery, Staff Map and Cassini
Integrated French historical layers help compare landscape evolution over different time scales.
IGN LiDAR HD online: compare DTM, DSM, height model and experimental LiDAR maps
GeoCalque integrates public map services derived from the French national IGN LiDAR HD programme. The programme provides classified point clouds and 50 cm digital models. GeoCalque uses the official WMTS hillshades, which are much lighter than displaying the raw 3D point cloud in a browser.
- DTM (Digital Terrain Model / MNT): ground relief with vegetation and buildings removed as far as possible. Particularly useful for old tracks, banks, ditches, terraces and microtopography under forest cover.
- DSM (Digital Surface Model / MNS): terrain plus vegetation, buildings, bridges and other above-ground features.
- Height model (MNH, DSM − DTM): emphasizes the relative height of buildings and vegetation.
- LiDAR Terrain Map and LiDAR Above-ground Map: experimental IGN cartographic products combining LiDAR-derived models with other map data. They are only available in the test areas published by IGN and coverage may evolve.
Why compare LiDAR with other maps?
Quick Comparison can place current IGN aerial imagery next to the LiDAR HD DTM and synchronize pan and zoom. Opacity or swipe makes it easy to separate vegetation from persistent terrain features. A LiDAR hillshade can also be used as the reference map when georeferencing a historical raster if a bank, sunken road or other topographic feature is identifiable in both sources.
GeoCalque can also draw an elevation profile directly from a line traced on the map. The profile queries the official Géoplateforme elevation service and prioritizes the LiDAR HD DTM where available. Distance and area measurement tools are available from the same map toolbar.
Raw data remain available as open data from IGN. GeoCalque does not host the point clouds; it consumes the official Géoplateforme services directly.
IGN LiDAR HD product documentation · LiDAR HD coverage · LiDAR HD point clouds · IGN experimental LiDAR maps
IGN LiDAR HD: common questions
Which LiDAR layer is best for finding historical terrain features?
Start with the LiDAR HD DTM. It represents ground relief while removing vegetation and buildings as far as possible, making old tracks, banks, ditches, terraces and microtopography easier to inspect.
What is the difference between DTM, DSM and the height model?
The DTM describes ground terrain, the DSM includes above-ground objects, and the height model emphasizes their relative height. The three views complement each other in Quick Comparison.
Why can a LiDAR area be blank?
LiDAR HD products are released progressively and regulated areas may contain no-data cells. The experimental LiDAR Terrain and Above-ground map layers are additionally limited to IGN test areas.
BRGM geology, InfoTerre, soils and cadastral data: layers and point queries
GeoCalque now connects several French public geodata services. BRGM / InfoTerre provides geology, subsurface and hazard layers through OGC WMS/WFS services; IGN provides cadastral parcel queries through API Carto; and GIS Sol / INRAE publishes the dominant soil map.
- Harmonized geological map 1:50,000 and simplified lithology 1:1,000,000 — BRGM / InfoTerre.
- Dominant soil map 1:250,000 — GIS Sol / INRAE.
- Cadastral parcels — IGN / DGFiP.
- BSS boreholes, underground cavities, ground movements, clay shrink-swell and groundwater flooding susceptibility — BRGM.
- AI land cover — CoSIA — IGN classification derived from aerial imagery, available as a land-cover layer where coverage has been released.
Point information
The Point info checkbox is available directly on the map. Click a location and GeoCalque queries only the enabled sources, including cadastral parcels, geology, soils, LiDAR HD and CoSIA where available. Displaying a visual layer and querying it are independent, so the map can remain uncluttered.
BRGM / InfoTerre OGC services · IGN cadastral API · GIS Sol dominant soil map
Your own map sources
Local archives, national libraries, university collections, map libraries, IIIF repositories and private collections can all provide usable source rasters. GeoCalque does not need a map to be cadastral: estate plans, fire-insurance maps, military maps, town plans and scanned atlases can all be georeferenced.