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Extract Raster from WCS in QGIS with Cell Snapping and Resolution Matching Original Raster

Geographic Information Systems Asked on July 19, 2021

I am trying to extract a subset of data from WCS Coverage. I right-click the coverage > Export > Save As. This brings in this dialog box.

enter image description here

But when I export it does not snap the raster cell to the original raster and the cell size changes as well. See this:

enter image description here

Is there a way in QGIS to get raster data from WCS for a particular area and have cells exactly the same as raw data?

Request sent by QGIS is:

http://localhost:8080/qgis-server/WCSServer?SERVICE=WCS&VERSION=1.0.0&REQUEST=GetCoverage&FORMAT=GeoTIFF&COVERAGE=dem&BBOX=11878792.03174479678273201,7007814.11248470470309258,11882060.6795082800090313,7011082.79411716014146805&CRS=EPSG:2283&RESPONSE_CRS=EPSG:2283&WIDTH=1000&HEIGHT=1000

One Answer

Note in the WCS 1.0.0 specification it tells us that (I've split the paragraph to emphasise how to avoid resampling):

In response to a GetCoverage request, a WCS server will return a grid of the requested size covering the requested area. This usually requires interpolating / resampling the coverage values stored on the server.

To avoid any interpolation / resampling, clients should request the coverage in a native CRS stated by the server; and select a GML Envelope whose extent exactly matches that of the requested GML Grid. For such a request, if the chosen CRS is “Image” or “Engineering”, the Envelope and Grid must both describe grids of the same size. For other CRSs, the Envelope and Grid must be related by the offsetVector values in the coverage description (if supplied in the coverage description).

Correct answer by nmtoken on July 19, 2021

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