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Elevation and hillshade

Source: R/layers-raster.R
mn_elevation.Rd

Terrain rasters for Mongolia from the Copernicus DEM GLO-90.

Usage

mn_elevation(
  resolution = c("1km", "90m"),
  within = NULL,
  mask = TRUE,
  crs = NULL
)

mn_hillshade(
  resolution = c("1km", "90m"),
  within = NULL,
  mask = TRUE,
  angle = 40,
  direction = 315,
  crs = NULL
)

Arguments

resolution

"1km" or "90m".

within

Area to return (names or codes). Required for the online resolutions: "90m" elevation and "10m" land cover.

mask

If TRUE (default), cells outside Mongolia (or outside within) are set to NA.

crs

Coordinate reference system of the result. NULL (default) keeps longitude/latitude (EPSG:4326). Use "albers", "lcc" or "utm" for a projection suited to Mongolia (see mn_crs()), or any value accepted by sf::st_crs().

angle, direction

Sun elevation and direction (degrees) for the hillshade.

Value

A terra SpatRaster: elevation in metres, or hillshade values between 0 and 1.

Details

  • resolution = "1km" (default): a national grid in the Albers projection, downloaded once (about 5 MB) and cached.

  • resolution = "90m": the original 90 m data, read directly from the cloud for the area in within (an aimag or smaller). Nothing is cached.

mn_hillshade() computes shaded relief from the elevation, for a background under other layers.

Source

Copernicus DEM GLO-90, (c) DLR e.V. 2010-2014 and (c) Airbus Defence and Space GmbH 2014-2018, provided under COPERNICUS by the European Union and ESA. Free to use with attribution.

See also

Other raster layers: mn_landcover(), mn_population(), mn_zonal()

Examples

elev <- mn_elevation()
#> ℹ Downloading Elevation, 1 km (Copernicus DEM) (4.1 MB); this happens once.
terra::plot(elev)

ub <- mn_elevation("90m", within = "Ulaanbaatar")
terra::plot(mn_hillshade(within = "Khovd"), col = grey.colors(100), legend = FALSE)