Hi Lists,
I'm cross posting this to GeoServer-Users over from QGIS-Dev as the
current QGIS code seems to be trying to work around a GeoServer quirk
based on Nyall's code-comment snippet.
Is there something different QGIS can do to work around the stated issue
in a better way given I guess requesting a 10x10 Coverage via WCS isn't
going to be doing the host server any favours?
Cheers,
Jonathan
On 2018-10-15 00:54, Nyall Dawson wrote:
I can't explain the background here, but it seems deliberate. There's
a comment before this request is made:
"
// It may happen (GeoServer) that extent reported in
spatialDomain.Envelope is larger
// than the coverage. Then if that larger BBOX is requested, the
server returns
// request BBOX intersected with coverage box scaled to requested
WIDTH and HEIGHT.
// GDAL WCS client does not suffer from this probably because it
probably takes
// extent from lonLatEnvelope (it probably does not calculate it from
// spatialDomain.RectifiedGrid because calculated value is slightly
different).
// To get the true extent (it can also be smaller than real if
reported Envelope is
// than real smaller, but smaller is safer because data cannot be
shifted) we make
// request of the whole extent cut the extent from spatialDomain.Envelope if
// necessary"
getCache( 1, mCoverageExtent, 10, 10 );
Radim may know more and may be able to explain if this workaround is
still necessary
Nyall
Hi,
using our national DEM WCS:
https://geodata.nationaalgeoregister.nl/ahn3/wcs?
Loading the layer ahn3_5m_dtm for an area of a couple of km in
epsg:28992 is very slow.
I'm not so familiar with the WCS specs, but I see QGIS asking:
https://geodata.nationaalgeoregister.nl/ahn3/wcs?SERVICE=WCS&VERSION=1.0.0&REQUEST=GetCoverage&FORMAT=GEOTIFF_FLOAT32&COVERAGE=ahn3_5m_dtm&BBOX=10000,250000,356250,618750&CRS=EPSG:28992&RESPONSE_CRS=EPSG:28992&WIDTH=10&HEIGHT=10
which is the whole of the Netherlands (in a 10x10 pixel output??) and
after that a more proper bbox.
Is this supposed to go like this?
I reckon that (if the WCS data does not have overviews), loading the
whole dataset all the time is pretty intensive.
Anybody more familiar with this can tell something about this?
Regards,
Richard Duivenvoorde
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