Get elevation for lat/long points from a data.frame or list of points.

Uses the GeoNames web service

Usage

elevation(
  input = NULL,
  latitude = NULL,
  longitude = NULL,
  latlong = NULL,
  elevation_model = "srtm3",
  username = Sys.getenv("GEONAMES_USER"),
  key,
  curlopts,
  ...
)

Arguments

input

A data.frame of lat/long data. There must be columns decimalLatitude and decimalLongitude.

latitude

A vector of latitude's. Must be the same length as the longitude vector.

longitude

A vector of longitude's. Must be the same length as the latitude vector.

latlong

A vector of lat/long pairs. See examples.

elevation_model

(character) one of srtm3 (default), srtm1, astergdem, or gtopo30. See "Elevation models" below for more

username

(character) Required. An GeoNames user name. See Details.

key, curlopts

defunct. see docs

...

curl options passed on to crul::verb-GET see curl::curl_options() for curl options

Value

A new column named elevation_geonames in the supplied data.frame or a vector with elevation of each location in meters. Note that data from GBIF can already have a column named elevation, thus the column we add is named differently.

GeoNames user name

To get a GeoNames user name, register for an account at http://www.geonames.org/login - then you can enable your account for the GeoNames webservice on your account page (http://www.geonames.org/manageaccount). Once you are enabled to use the webservice, you can pass in your username to the username parameter. Better yet, store your username in your .Renviron file, or similar (e.g., .zshrc or .bash_profile files) and read it in via Sys.getenv() as in the examples below. By default we do Sys.getenv("GEONAMES_USER") for the username parameter.

Elevation models

• srtm3:

  • sample area: ca 90m x 90m

  • result: a single number giving the elevation in meters according to srtm3, ocean areas have been masked as "no data" and have been assigned a value of -32768

• srtm1:

  • sample area: ca 30m x 30m

  • result: a single number giving the elevation in meters according to srtm1, ocean areas have been masked as "no data" and have been assigned a value of -32768

• astergdem (Aster Global Digital Elevation Model V2 2011):

  • sample area: ca 30m x 30m, between 83N and 65S latitude

  • result: a single number giving the elevation in meters according to aster gdem, ocean areas have been masked as "no data" and have been assigned a value of -32768

• gtopo30:

  • sample area: ca 1km x 1km

  • result: a single number giving the elevation in meters according to gtopo30, ocean areas have been masked as "no data" and have been assigned a value of -9999

References

GeoNames http://www.geonames.org/export/web-services.html

Examples

if (FALSE) { # \dontrun{
user <- Sys.getenv("GEONAMES_USER")

occ_key <- name_suggest('Puma concolor')$key[1]
dat <- occ_search(taxonKey = occ_key, limit = 300, hasCoordinate = TRUE)
head( elevation(dat$data, username = user) )

# Pass in a vector of lat's and a vector of long's
elevation(latitude = dat$data$decimalLatitude[1:10],
  longitude = dat$data$decimalLongitude[1:10],
  username = user, verbose = TRUE)

# Pass in lat/long pairs in a single vector
pairs <- list(c(31.8496,-110.576060), c(29.15503,-103.59828))
elevation(latlong=pairs, username = user)

# Pass on curl options
pairs <- list(c(31.8496,-110.576060), c(29.15503,-103.59828))
elevation(latlong=pairs, username = user, verbose = TRUE)

# different elevation models
lats <- dat$data$decimalLatitude[1:5]
lons <- dat$data$decimalLongitude[1:5]
elevation(latitude = lats, longitude = lons, elevation_model = "srtm3")
elevation(latitude = lats, longitude = lons, elevation_model = "srtm1")
elevation(latitude = lats, longitude = lons, elevation_model = "astergdem")
elevation(latitude = lats, longitude = lons, elevation_model = "gtopo30")
} # }