ogc_get_maastotietokanta {geofi} | R Documentation |
Download a Collection from the Maastotietokanta (Topographic Database)
Description
Downloads a specific collection of spatial data from the Maastotietokanta (Topographic Database) using the OGC API provided by the National Land Survey of Finland (NLS).
Usage
ogc_get_maastotietokanta(
collection = "hautausmaa",
crs = 3067,
limit = NULL,
max_pages = 100,
bbox = NULL,
api_key = getOption("geofi_mml_api_key")
)
Arguments
collection |
Character. The name of the collection to download (e.g.,
|
crs |
Numeric or Character. The coordinate reference system (CRS)
for the output data, specified as an EPSG code. Supported values are
|
limit |
Numeric or NULL. The maximum number of features to retrieve in
a single API request. If |
max_pages |
Numeric. The maximum number of pages to fetch during pagination
when |
bbox |
Character or NULL. A bounding box to filter the data, specified as
a string in the format |
api_key |
Character. API key for authenticating with the Maastotietokanta
OGC API. Defaults to the value stored in
|
Details
This function retrieves spatial data from the Maastotietokanta (Topographic Database) OGC API, provided by the National Land Survey of Finland (NLS). It acts as a wrapper around a lower-level API request function, adding user-friendly features like CRS transformation and spatial filtering.
Key features:
Supports pagination for large collections when
limit=NULL
.Limits the number of pages fetched during pagination using
max_pages
.Applies spatial filtering using a bounding box (
bbox
).Transforms the output to the specified CRS (
crs
).Validates inputs to prevent common errors.
To see the list of available collections, use
ogc_get_maastotietokanta_collections
.
For very large collections (e.g., "suo"
), the function may fetch data in
pages of 10,000 features each. If the number of pages exceeds max_pages
,
a warning is issued, and only the features from the first max_pages
pages
are returned. Increase max_pages
to retrieve more features, but be aware
that this may significantly increase runtime.
Value
An sf
object containing the spatial features from the specified
collection, transformed to the requested crs
.
Author(s)
Markus Kainu markus.kainu@kapsi.fi
See Also
ogc_get_maastotietokanta_collections
to list available collections.
https://www.maanmittauslaitos.fi/en/maps-and-spatial-data/datasets-and-interfaces/product-descriptions/topographic-database
for more information on the Maastotietokanta.
https://www.maanmittauslaitos.fi/en/rajapinnat/api-avaimen-ohje for
instructions on obtaining an API key.
Examples
## Not run:
# Set your API key
options(geofi_mml_api_key = "your_api_key_here")
# Download the "hautausmaa" (cemeteries) collection in EPSG:3067
cemeteries <- ogc_get_maastotietokanta(collection = "hautausmaa")
print(cemeteries)
# Download the "suo" (bogs/marshes) collection with a higher page limit
bogs <- ogc_get_maastotietokanta(
collection = "suo",
max_pages = 500
)
print(bogs)
# Download with a bounding box (in EPSG:4326) and transform to EPSG:4326
cemeteries_bbox <- ogc_get_maastotietokanta(
collection = "hautausmaa",
bbox = "24.5,60.1,25.5,60.5",
crs = 4326
)
print(cemeteries_bbox)
## End(Not run)