Retrieve SRTM tiles

Last update: Oct. 2016
   

This service provides a TIFF image with values from the SRTM (Shuttle Radar Topography Mission) Digital Elevation Model.

Available worldwide and for free. WGS 84 projection (=constant step in latitudes and longitudes).

Command:

http://www.webservice-energy.org/mapserv/srtm?SERVICE=WMS&VERSION=1.3.0&REQUEST=GetMap&
BBOX=min_lat,min_lon,max_lat,max_lon&
CRS=EPSG:4326&WIDTH=nb_pix&HEIGHT=nb_pix&LAYERS=srtm_version&FORMAT=image/tiff

with:

  • min_lon: west bound of your bbox
  • max_lon: east bound of your bbox
  • min_lat: south bound of your bbox
  • max_lat: north bound of your bbox
  • nb_pix: size of the image in pixels
  • srtm_version: srtm_s0 (full resolution, 16 bits), srtm_s2 (½ resolution srtm_s0), srtm_s4 (½ resolution srtm_s2), or srmt_s8 (8 bits, ½ res. srtm_s4)
NB: min_lon, max_lon, min_lat, and max_lat are given on the edges of the pixels, like for GDAL librairies. Please not that this description is different from the one you use for instance in Matlab, where on works on centers of pixels.
Characteristics:
The webservice supplies a map of max 2048 by 2048 pixels. Where SRTM is not defined, i.e. in the water areas, value is -32768 or -2ˆ15. The highest spatial resolution is 5°/6000 pixels, which means that 1 pixel corresponds to 0.000833° (= 3" = 3*1/3600). If you request a pixel size higher than the spatial resolution, an undersampling operator is applied to create a coarser image. Whereas, if the requested pixel size is smaller than the spatial resolution, a bilinear oversampling is applied on the image.

Don't hesitate to explore the webservice-energy.org catalog.

 

Example

Retrieve the SRTM tile over Corsica (right illustration =>)

http://www.webservice-energy.org/mapserv/srtm?SERVICE=WMS&VERSION=1.3.0&REQUEST=GetMap&
BBOX=41.2,8.3,43.2,9.8&
CRS=EPSG:4326&WIDTH=600&HEIGHT=1000&LAYERS=srtm_s0&FORMAT=image/tiff

Click on the image to magnify

Over the reunion Island - 1 km spatial resolution:

http://www.webservice-energy.org/mapserv/srtm?SERVICE=WMS&VERSION=1.3.0&REQUEST=GetMap&BBOX=-22,55,-20,56&CRS=EPSG:4326&WIDTH=120&HEIGHT=240&LAYERS=srtm_s0&FORMAT=image/tiff

NB: the location of the centers and corners of the MSG pixels are overlayed on the DEM.