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I have a DEM layer from WCS.

How can I download the data to process it to get slope, aspects, etc in QGIS?

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A GetCoverage request will fetch the data, you can hand craft and run in a browser then process in QGIS if you don't want to use QGIS directly to get the data.

For example you could do a subset request for ASCII grid like:

http://servicios.idee.es/wcs-inspire/mdt?version=2.0.1&request=GetCoverage&service=WCS&CoverageID=Elevacion4258_500&outputformat=application/asc&subset=lat(27.63,30&subset=long(33,44.21)&

The service does work in QGIS though, just use the endpoint https://servicios.idee.es/wcs-inspire/mdt?

QGIS will make WCS 1.0.0 GetCoverage requests like:

http://servicios.idee.es/wcs-inspire/mdt?SERVICE=WCS&VERSION=1.0.0&REQUEST=GetCoverage&FORMAT=GEOTIFF_RGB&COVERAGE=Elevacion4258_1000&BBOX=-18.21086854580000036,27.59329243879999893,4.4980704786506962,43.84847187162309723&CRS=EPSG:4258&RESPONSE_CRS=EPSG:4258&WIDTH=591&HEIGHT=424

I tried the Elevacion4258_25 coverage, and it does eventually return though it's large and slow. I assume from its name that it is in epsg:4258, and probably you should avoid trying to reproject it and display it at the same time, if fetching through QGIS (i.e. set the project to the same CRS as the coverages you are requesting).

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  • Does the subset call return the actual data rather than rescaling it?. QGIS bbox calls are rescaling the data. I want the actual data with exact same raster cell size and snapping. May 8 at 13:23
  • the subset request parameters on their own should return the actual data. Additional parameters may be appended to the GetCoverage request to rescale it though.
    – nmtoken
    May 12 at 8:08
  • so subset calls are different than QGIS bbox calls? Also, my WCS version is 1.0. Does version 1.0 support subset calls? This is the calls QGIS is making if I am trying to save raster layer: localhost:8080/qgis-server/… May 12 at 14:43
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    The concept of subsetting exists in WCS 1, but the the mechanics of making a subset request have changed between versions. WCS 1 is now deprecated you are encouraged to move to WCS 2. To understand subsetting in WCS 1.0 read the specification ~ portal.ogc.org/files/05-076
    – nmtoken
    May 13 at 7:50
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I assume that this is the same question as Using WCS DEM data for make slope and aspect maps in QGIS, which provided the following URL:

https://servicios.idee.es/wcs-inspire/mdt?version=2.0.1&request=GetCapabilities&service=WCS

In which case, it SHOULD be as simple as adding the URL as a WCS layer in the QGIS Browser. However I just tested it out using the above URL, and it didn't work. (It worked in my browser, so I have access). Error message is "Could not understand the response: WCS server version 2.0.1 is not supported by QGIS (supported versions: 1.0.0, 1.1.0, 1.1.2)

Tried URL: https://servicios.idee.es/wcs-inspire/mdt?version=2.0.1&SERVICE=WCS&REQUEST=GetCapabilities&AcceptVersions=1.1.0,1.0.0"

Also QGIS documentation here, says it only supports v1.0 and v1.1:

https://docs.qgis.org/testing/en/docs/user_manual/working_with_ogc/ogc_client_support.html#wcs-client )

Amended Answer* I may have found a few bugs in QGIS here. It appears that the WCS Connection manager will 'cache' the URL its attempting to use. So even though I amended the URL of the connection, it didn't work. But it DID work, when I added a brand new connection with the same URL. Apologies for the above confusion. So its possible if you are having connection issues, get rid of any existing WCS connections and start a new one with just the "https://servicios.idee.es/wcs-inspire/mdt" URL as suggested by other user.

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    Elevacion4258_1000 Works for me in QGIS, just use the https://servicios.idee.es/wcs-inspire/mdt? part of the URL. Elevacion4258_25 keeps timing out for me, but that's a service issue.
    – nmtoken
    Jul 24 '20 at 10:05
  • nope still no dice for me on that URL - BUT i just remembered that Ive had similar issue before where - I had access through a browser but not desktop application and - if i remember correctly it had something to do with port settings for incoming URL's on particular application, so ill maybe test this out at home to confirm this.
    – nr_aus
    Jul 27 '20 at 0:48
  • ok apologies, I stand corrected - sort of!...….well I don't know now myself! I checked the URL on my home computer, and as I expected, it worked. Checked again today at my work, expecting it to fail again, but this time, it worked?!?!?! Tried a new connection with the same connection parameters - fail. so I suspect something fishy is going on there with QGIS. I will amend my response above to reflect this.
    – nr_aus
    Jul 28 '20 at 2:14

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