Conversion for latitude/longitude to altitude in R

Asked 23/1, 2012 at 15:5 Answered 27/1, 2022 at 12:48

Does anyone know if there is a tool in R to find the height above sea level of a location, given the latitude and longitude ?

Whinchat answered 23/1, 2012 at 15:5 Comment(1)

You want to find what the altitude of a given location on the Earth's surface is? – Schalles 23/1, 2012 at 15:18

Or you can use the package that looks up from geonames, and get the value from the srtm3 digital elevation model:

First get a geonames username by registering at geonames.org. Then set it:

> options(geonamesUsername="myusernamehere")

then:

> require(geonames)
> GNsrtm3(54.481084,-3.220625)
  srtm3       lng      lat
1   797 -3.220625 54.48108

or the gtopo30 model:

> GNgtopo30(54.481084,-3.220625)
  gtopo30       lng      lat
1     520 -3.220625 54.48108

geonames is on CRAN so install.packages("geonames") will get it.

The difference between these two models is because they are only approximations based on satellite data. Don't go expecting to pinpoint mountains from this.

Zischke answered 23/1, 2012 at 17:24 Comment(5)

That's why I wrote it :) - the geonames package! – Zischke 23/1, 2012 at 19:16

I get the message that I need to pass my username. I found geonames.org/export/web-services.html#srtm3 but it doesn't say how to do this through the GNsrtm3 function (and it doesn't seem the function can take username as an argument) – Habana 17/3, 2015 at 22:31

@DavidLeBauer: add this command before running the function: options(geonamesUsername="YourUserName") – Israelitish 15/8, 2017 at 11:44

@Zischke Is this function obsolete now? It says. Error in url(url, open = "r") : cannot open the connection to 'http://api.geonames.org/srtm3JSON?lat=NA&lng=NA& It doesn't work even on dummy data..same error – Vassalize 4/7, 2021 at 1:50

@Biotechgeek still works for me, but since 2012 you need a username for the API - edit done! – Zischke 4/7, 2021 at 16:20

Update: Earthtools no longer exists, so this answer is obsolete. I recommend @Spacedman's answer instead.

As DWin said, there are two parts to this: find a good source of data with a web service, then parse it in R. This answer uses the earthtools.org service.

library(RCurl)
library(XML)

latitude <- 52.4822
longitude <- -1.8946
url <- paste(
    "http://www.earthtools.org/height",
    latitude, 
    longitude,
    sep = "/"
)

page <- getURL(url)
ans <- xmlTreeParse(page, useInternalNodes = TRUE)
heightNode <- xpathApply(ans, "//meters")[[1]]
(height <- as.numeric(xmlValue(heightNode)))

Clockwise answered 23/1, 2012 at 15:44 Comment(4)

What you have looked pretty interesting and so I tried it on a lat and long I knew of a town link. I used latitude <- 41.25 & longitude <- -77.3 yielding 293 not 597 as expected. Am I using this incorrectly? – Stereochemistry 23/1, 2012 at 17:15

The problem is most likely related to the quality of the data. Heights above sea level are given at 3 arc second (approximately 90m) resolution according to the linked Earth Tools page. In 90m, you can have a lot of hill, so don't expect perfect accuracy. – Clockwise 23/1, 2012 at 17:39

Also, 41.25 degrees is not the same as 41deg, 25sec since there are only 60 seconds in a degree. Using the correct location, the service returns 568m. – Clockwise 23/1, 2012 at 17:46

Thanks. This is not my area of research but the R solution looked pretty interesting. Ignorantly I thought 41 degrees 25' (minutes) was just a decimal. Wrong! Thanks for the information. For others like me (ignorant) the conversion is simple. Multiply the minutes by 60 and that's your decimal. I gathered this from link Thanks for sharing. – Stereochemistry 23/1, 2012 at 19:43

You can access elevation data through Google Maps Elevation API. And in R you can use this through my googleway package

To use Google Maps API you need an API key

library(googleway)

api_key <- "your_api_key"

df_locations <- data.frame(lat = c(54.481084), lon = c(-3.220625))

google_elevation(df_locations = df_locations, key = api_key)

# $results
# elevation location.lat location.lng resolution
# 1  813.9291     54.48108    -3.220625   610.8129
# 
# $status
# [1] "OK"

Ruisdael answered 20/1, 2017 at 23:13 Comment(0)

There are R packages such as RCurl that allow web queries. There are also web resources, Further specfics will require .... well, ... more specifics.

http://gisdata.usgs.net/xmlwebservices2/elevation_service.asmx?op=getElevation

Tymbal answered 23/1, 2012 at 15:33 Comment(0)

You can also use package rgbif which uses geonames internally. I like this option because you can provide a data frame as input, as well as other input formats. Again, you need to provide your GeoNames user name.

library(rgbif)

coords <- data.frame(decimalLatitude = 54.481084, 
                     decimalLongitude = -3.220625)

elevation(coords, username = "myusernamehere")

If you provide a data frame as input, it must contain the coordinates columns named as decimalLatitude and decimalLongitude, which relates to the DarwinCore standards.

You can choose among different options of models using the argument 'elevation_model'.

Keniakenilworth answered 27/1, 2022 at 12:48 Comment(1)

Shows Error: Unauthorized (HTTP 401) when I run your code, after replacing myusername here with my geonames ID. Any idea why? – Lally 22/12, 2023 at 15:1

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