Segmenting France Across Four Centuries

Marta López-Rauhut, Hongyu Zhou, Loic Landrieu, Mathieu Aubry

Historical maps pre-date satellite imagery, offering insights into centuries of landscape transformation before the 1950s. Unlocking this information can, for example, support the development of sustainable long-term policies.

Visually comparing maps from different eras is a complex task. Segmenting the maps into Land Use and Land Cover (LULC) classes makes it easier, but segmenting maps manually is still extremely time-consuming. That is why several works have explored training models to segment historical maps automatically. However, the lack of annotated training data remains a major limitation.

We introduce FRAx4, a new dataset of historical maps tailored for analyzing long-term LULC evolution with limited annotations.

Description

FRAx4 spans metropolitan France (548,305 km²) across the 18th, 19th, 20th and 21st centuries, and considers four LULC segmentation classes:

Map collections
- Cassini
- État-Major
- SCAN50
- Plan IGN
Segmentation classes:
- background
- forest
- buildings
- hydrography
- road

Dataset content

For each historical map collection:

10952 historical map tiles
470 historical label tiles*
Modern Plan IGN maps adapted to resemble the style of the historical map collection:
- 10952 modern map tiles
- 10952 modern label tiles

Additionally, settings.json stores the exact settings that were used to generate the dataset and tile_extents.csv provides the west, south, east and north coordinates of each tile.

	Cassini (Historical)	Cassini (Modern)		État-Major (Historical)	État-Major (Modern)		SCAN50 (Historical)	SCAN50 (Modern)
Map
Labels							Not available

*Historical labels are available for a subset of map sheets, for Cassini and État-Major. Namely: Cambrai, Clermont, Dunkerque, LaonNoyon, LePuy, SaintMalo, SaintMalo2 and SaintOmer.

Dataset structure

<root dir>/
├─ <map collection>/
│  ├─ historical/
│  │  ├─ labels/
│  │  ├─ raster/
│  │  ├─ raster_labeled/
│  ├─ modern/
│  │  ├─ labels/
│  │  ├─ raster/
...

For convenience, historical/raster_labeled/ contains a duplicate of the labeled subset of historical/raster/.

Data sources

The dataset is built based on the map layers contained in a QGIS project. Some of these layers are served online using a known protocol (WMS/WFS/TMS...), others had to be downloaded and extracted manually before adding them to the project. We adopt the following structure to identify the map layer sources:

<source url>, [<protocol> | File] - layer or file name (<provider>)

Here, File refers to a manually downloaded and extracted layer. The annotation layer sources follow a similar format.

Map layers

Cassini: https://geohistoricaldata.org/geoserver/cassini-ehess/wms, WMS - CASSINI (EHESS/CRH, accessed through GeoHistoricalData)
État-Major: https://data.geopf.fr/wms-r/wms?VERSION=1.3.0, WMS - GEOGRAPHICALGRIDSYSTEMS.ETATMAJOR40 (IGN Géoservices)
SCAN50: https://data.geopf.fr/wms-r/wms?VERSION=1.3.0, WMS - GEOGRAPHICALGRIDSYSTEMS.MAPS.SCAN50.1950 (IGN Géoservices)
Plan IGN: https://data.geopf.fr/tms/1.0.0/PLAN.IGN/{z}/{x}/{y}.pbf TMS - PLAN.IGN (IGN Géoservices)

Annotation layers

Cassini: two separate sources (both accessed through GeoHistoricalData):
- https://geohistoricaldata.org/geoserver/cassini-vectors/wfs
  - WFS - cassini-vectors:france_cassini_forets (Vallauri, D. et al.)
- https://geohistoricaldata.org/data/cassini.tar.gz (Perret, J. et al., dataset: Perret, J. et al.)
  - File - cities_and_domains
  - File - hydrography_areas
  - File - hydrography_network
  - File - roads_clean_topology
We manually corrected and completed the annotations. The final version can be found here.
État-Major: https://data.geopf.fr/telechargement/download/BDCARTO-EM/<dept>/<dept>.7z (IGN Géoservices)
- File - C_1_2_OCS_ANCIEN_SANS_BATI
- File - C_2_1_BATIMENT
- File - B_1_TRONCON_DE_ROUTE
- File - B_3_TRONCON_DE_COURS_D_EAU
The data is provided as separate archives for each department of France. The sources are listed in https://geoservices.ign.fr/bdcarto-em, but the download links follow the pattern shown above. We employed the sources that were available in April 2024.

We manually merged, corrected and completed the annotations, including the addition of a surface hydrology layer for our test set. The final version can be found here.
SCAN50: we found no annotations for these maps.
Plan IGN: annotations are derived from the vectorized map layers, by isolating the geographical features that belong to each class.

Map sheet mosaic

We downloaded the map sheet vertex coordinates of the Cassini collection from the GeoHistoricalData portal. Dataset tiles are obtained by subdividing each map sheet with a minimum tile size constraint (in pixels).

Cassini sheet mosaic: https://geohistoricaldata.org/geoserver/cassini-ehess/wfs, WFS - cassini-vectors:france_cassini_table_assemblage (GeoHistoricalData)

Citation

Coming soon

Acknowledgements

This work was supported by the European Research Council (ERC project DISCOVER, number 101076028) and by ANR project sharp ANR-23-PEIA-0008 in the context of the PEPR IA. This work was also granted access to the HPC resources of IDRIS under the allocation 2024-AD011015314 made by GENCI.

Datasets:

martalorau
/

FRAx4