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Efficiently retrieve EUNIS land cover data from the EEA Ecosystem Type Map

Source: R/data_eunis.R
get_eunis_data.Rd

This function retrieves EUNIS (European Nature Information System) land cover data for a Region of Interest (ROI), as an alternative to the French OCS-GE nomenclature used by get_ocsge_data_fgb. It queries the European Environment Agency (EEA) "Ecosystem Type Map v3.1, terrestrial part" ArcGIS MapServer, a 100 m resolution, EEA-39-wide classified raster available at EUNIS Level 1 (9 broad classes) or Level 2 (46 detailed classes).

Usage

get_eunis_data(
  roi,
  level = c("L1", "L2"),
  resolution = 100,
  service_url =
    "https://bio.discomap.eea.europa.eu/arcgis/rest/services/Ecosystem/EcosystemTypeMap_v3_1_Terrestrial/MapServer"
)

Arguments

roi

An sf (or sfc) object defining the Region Of Interest. It can be in any projection, but will be transformed to EPSG:3035 (ETRS89-LAEA Europe) internally, the native grid of the source service.

level

Character. "L1" (9 broad classes, default) or "L2" (46 detailed classes). See Details for a caveat on "L2".

resolution

Numeric. Requested pixel size in meters. Default is 100, the native resolution of the source raster; values below 100 only upsample without adding real detail. Use a coarser value for large ROIs to stay under the service's image-size limit (see Details).

service_url

Character. The ArcGIS MapServer base URL. Exposed mainly for testing against a different endpoint.

Value

A categorical SpatRaster in EPSG:3035, with cell values pointing to a factor level table (levels) giving the EUNIS code for that level (see ref_eunis for the matching labels and colors). Cells outside the mapped terrestrial extent (e.g. sea) are NA.

Details

Unlike the OCS-GE FlatGeobuf source, this EUNIS layer has no raw-value raster endpoint (no ArcGIS ImageServer is published for it) – only a symbolized MapServer export. This function requests that export image at the native resolution with nearest-neighbor resampling (so pixel colors are not blended at class boundaries), then decodes each pixel's exact RGB color back into an EUNIS code using the fixed legend palette shipped as ref_eunis.

Limitations:

  • The service caps a single export at 4096 x 4096 pixels. At the default 100 m resolution that is about 410 x 410 km; larger ROIs must use a coarser resolution or be split and fetched in tiles.

  • At level = "L2", two pairs of classes are rendered with the identical color by the source service and cannot be told apart from the image alone: D5/F6 and D6/F7. Affected pixels are returned with a combined code (e.g. "D5/F6") rather than silently assigned to one of the two. level = "L1" has no such collision.

  • Areas outside the mapped terrestrial extent (e.g. open sea) are detected from the export's alpha channel and returned as NA, not guessed from color.

Note

This function requires a working internet connection.

See also

ref_eunis for the EUNIS code/label/color lookup table, and get_ocsge_data_fgb for the equivalent OCS-GE fetcher.

Examples

if (FALSE) { # \dontrun{
  library(sf)

  my_roi <- st_as_sf(data.frame(
    lon = c(2.3, 2.4, 2.4, 2.3, 2.3),
    lat = c(48.8, 48.8, 48.9, 48.9, 48.8)
  ), coords = c("lon", "lat"), crs = 4326) |> st_combine() |> st_cast("POLYGON")

  eunis_data <- get_eunis_data(roi = my_roi, level = "L1")
  terra::plot(eunis_data)
} # }