elev() downloads elevation data the Shuttle Radar Topography Mission
(SRTM), specifically the hole-filled CGIAR-SRTM (90 m resolution) for
latitudes between -60 and 60 or Mapzen's synthesis digital elevation product.
elev(output_dir, location, e_source = "mapzen", verbose = FALSE, ...)Character (e.g., "../Desktop/chelsa"). Pathway to where
the data will be stored.
A "sp", "sf" polygon or point object. See
sf::st_polygon to make polygons and sf::st_as_sf to make point
objects.
Character (e.g., mapzen or geodata). Indicating the
elevation data source.
Logical specifying whether to display verbose output when downloading from Mapzen.
Additional arguments to download.file().
elev() is called for its side-effects.
It invisibly returns a "SpatRaster" object if files were downloaded
successfully, and returns NULL otherwise. If the elevation data is sourced
from geodata the SpatRaster is downloaded at a spatial resolution of 30 arc
seconds (~1 km sq.). If elevation data is from Mapzen then the
SpatRaster will be a mosaic. Specifically, Mapzen's SpatRaster is unique as
it combines several sources of digital elevation models, including SRTM, the
ArcticDEM (covering all areas north of 60°), EUDEM (digital elevation
model over Europe; for review, see Mouratidis & Ampatzidis, 2019), and others
into a single product. The resolution of this SpatRaster was set to 7,
corresponding to 611.5 m ground resolution at 60° latitude 864.8 m at
45° and 1223 m at 0°.
Hijmans, R.J., Barbosa, M., Ghosh, A., & Mandel, A. (2023). geodata: Download Geographic Data. R package version 0.5-8. https://CRAN.R-project.org/package=geodataHollister, J. (2022). elevatr: Access Elevation Data from Various APIs. R package version 1.0.0. doi:10.5281/zenodo.5809645https://CRAN.R-project.org/package=elevatrMouratidis, A., & Ampatzidis, D. (2019). European Digital Elevation Model Validation against Extensive Global Navigation Satellite Systems Data and Comparison with SRTM DEM and ASTER GDEM in Central Macedonia (Greece). ISPRS International Journal of Geo-Information 8, 108. doi:10.3390/ijgi8030108
A more convenient function for other climate and elevation data
ce_download(). See sf::st_polygon to make polygons and sf::st_as_sf
to make point objects.
# \donttest{
# Make a small polygon
polygon_py_sm <- sf::st_polygon(
list(cbind(long = c(156, 156, 155, 156),
lat = c(-60, -59, -60, -60)))
)
polygon_py_sm <- sf::st_geometry(polygon_py_sm)
sf::st_crs(polygon_py_sm) <- "epsg:4326"
# Create temporary file
temp_path <- tempfile()
# elevation will be saved in the output_dir (i.e. output directory)
elev(output_dir = temp_path, location = polygon_py_sm)
#> Mosaicing & Projecting
# Reset user options
unlink(file.path(temp_path))
# }