# Is there a way to quickly get elevation/altitude given longitude and latitude?
**URL:** https://discourse.julialang.org/t/is-there-a-way-to-quickly-get-elevation-altitude-given-longitude-and-latitude/98781
**Category:** General Usage
**Tags:** question
**Created:** [May 13, 2023, 4:43am UTC](https://discourse.julialang.org/t/is-there-a-way-to-quickly-get-elevation-altitude-given-longitude-and-latitude/98781 "2023-05-13T04:43:32Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@schwob](https://discourse.julialang.org/u/schwob)
#### Post date: [May 13, 2023, 4:43am UTC](https://discourse.julialang.org/t/is-there-a-way-to-quickly-get-elevation-altitude-given-longitude-and-latitude/98781/1 "2023-05-13T04:43:32Z")
I have a data frame with longitude and latitude, and I would like to obtain the elevation/altitude for each point. At the moment, I use the `R` package `geonames`, which is a functional API for [geonames.org](http://geonames.org).
For example:
```julia
using RCall
lon = 10
lat = -5
@rput lon lat
R"""
library(geonames)
options(geonamesUsername = "username")
elev = unlist(GNsrtm3(lat, lon)[1])
"""
@rget elev
```
However, this method is incredibly time-consuming. I have data-frames with thousands of locations, and each `GNsrtm3()` takes 50+ seconds.
Do you know of a way that I can obtain the elevation/altitude quicker - preferably within Julia?
---
### Author:  [@blackeneth](https://discourse.julialang.org/u/blackeneth)
#### Post date: [May 13, 2023, 6:20am UTC](https://discourse.julialang.org/t/is-there-a-way-to-quickly-get-elevation-altitude-given-longitude-and-latitude/98781/2 "2023-05-13T06:20:28Z")
The [Geonames.org](http://Geonames.org) [web interface](https://www.geonames.org/export/web-services.html) is really simple for elevation data. You could roll your own query in a couple of lines of code using [HTTP.jl](https://github.com/JuliaWeb/HTTP.jl).
If you choose to have the data returned in JSON format, use [JSON3.jl](https://github.com/quinnj/JSON3.jl) to parse it out.
---
### Author:  [@joa-quim](https://discourse.julialang.org/u/joa-quim)
#### Post date: [May 13, 2023, 11:33am UTC](https://discourse.julialang.org/t/is-there-a-way-to-quickly-get-elevation-altitude-given-longitude-and-latitude/98781/3 "2023-05-13T11:33:41Z")
GMT is very fast in doing that but one need to have the grid with the altitudes stored locally.
From the name _GNsrtm3_ I assume the data is from the SRTM 3 arc seconds (~90 meters resolution) grid.
The GMT site stores several grids at different resolutions that can be downloaded automatically. But because high res data is very big we should download only an area of interest. The command
```julia
using GMT
gmt("docs data")
```
opens the site with the documentation about the available data sets and instructions on how to access with plain GMT (shell commands) instructions, but it’s actually very easy to do the same with the [GMT.jl](https://github.com/GenericMappingTools/GMT.jl) interface. For example, for your example case one will do
```julia
julia> G = grdcut("@earth_relief_03s", limits=(9,11,-6,-4));
GMT [WARNING]: Remote dataset given to a data processing module but no registration was specified - default to gridline registration (if available)
GMT [WARNING]: gmt_get_dataset_tiles: No earth_relief_03s_g tiles available for your region.
grdblend [NOTICE]: Remote data courtesy of GMT data server oceania [http://oceania.generic-mapping-tools.org]
grdblend [NOTICE]: SRTM15 Earth Relief original at 15x15 arc seconds [Tozer et al., 2019].
grdblend [NOTICE]: -> Download 10x10 degree grid tile (earth_relief_15s_p): S10E000
```
The download will be done only once and the data is stored in your computer for later use. Now to get the altitudes we use the [grdtrack](https://github.com/GenericMappingTools/GMT.jl) module that accepts a Mx2 matrix with _lon,lat_ (I think DataFrames will work as well)
But mind you if you are on Windows. There is a strange bug that only shows up on Windows, when the limits selected includes both land and ocean. In that case the best is to use a 15 arc seconds resolution grid (there are no 3 arc seconds global grids for the oceans).
```julia
julia> grdtrack([10 -5], G)
1×3 GMTdataset{Float64, 2}
Row │ Lon Lat Z
│ Float64 Float64 Float64
─────┼────────────────────────────
1 │ 10.0 -5.0 -2955.12
```
On the second run, that is after compiling,
```julia
julia> @time grdtrack([10 -5], G);
0.067492 seconds (1.11 k allocations: 70.727 KiB)
```
and if we had passed a thousands points the time would have been only slightly longer.
---
### Author:  [@schwob](https://discourse.julialang.org/u/schwob)
#### Post date: [May 13, 2023, 7:22pm UTC](https://discourse.julialang.org/t/is-there-a-way-to-quickly-get-elevation-altitude-given-longitude-and-latitude/98781/4 "2023-05-13T19:22:45Z")
This works perfectly! Thank you so much for your answer.