Bug report #20152

WCS client issues

Added by Richard Duivenvoorde over 5 years ago. Updated over 5 years ago.

Category:Web Services clients/WCS
Affected QGIS version:3.3(master) Regression?:No
Operating System: Easy fix?:No
Pull Request or Patch supplied:No Resolution:
Crashes QGIS or corrupts data:No Copied to github as #:27973


The following public wcs services:



Fail to work in QGIS3

Trying to load these (epsg:28992) services has several problems:
(looking into debug window for fired requests)

1) QGIS always fires a request for the full extent of the dataset (whole of the Netherlands in this case) in a 10x10px raster. In this case those requests timeout.

2) QGIS sometimes seems to load a raster (showing a black mapcanvas) but min/max values in Legend then show 0/0.

3) When trying to show the properties of a layer in such case, QGIS crashes (see below for stacktrace)

4) Not sure to me if this problem is due to the slowness of the service of the 'test'- or 'legendicon -requests OR if QGIS has a problem with the data

5) QGIS really needs a nodata value sometimes eg in the ahn2_5m layer, you really have to put a nodata value of -3.4028234663852886e+38 otherwise you have slowdown of QGIS.

Crash ID: 39ea8210ccdfce385a6120ee9d1e302811bca6bf

Stack Trace

QObject::inherits :
PyInit_sip :
PyInit_QtCore :
PyInit_QtCore :
PyInit_QtCore :
PyInit_QtCore :
PyInit_QtCore :
QMetaObject::activate :
QgsSymbolLayerMetadata::operator= :
QgsSymbolLayerMetadata::operator= :
QgsSymbolLayerMetadata::operator= :
QgsSymbolLayerMetadata::operator= :
QMetaCallEvent::placeMetaCall :
QObject::event :
QApplicationPrivate::notify_helper :
QApplication::notify :
QgsSymbolLayerMetadata::operator= :
QCoreApplication::notifyInternal2 :
QCoreApplicationPrivate::sendPostedEvents :
qt_plugin_query_metadata :
QEventDispatcherWin32::processEvents :
TranslateMessageEx :
TranslateMessage :
QEventDispatcherWin32::processEvents :
qt_plugin_query_metadata :
QEventLoop::exec :
QCoreApplication::exec :
QgsMapToolAnnotation::annotationItems :
BaseThreadInitThunk :
RtlUserThreadStart :

QGIS Version: 3.3.0-Master
QGIS code revision: 9cae77f262
Compiled against Qt: 5.11.2
Running against Qt: 5.11.2
Compiled against GDAL: 2.3.2
Running against GDAL: 2.3.2

System Info
CPU Type: x86_64
Kernel Type: winnt
Kernel Version: 6.1.7601


#1 Updated by Jonathan Moules over 5 years ago

Should this not have the "crashes qgis" flag ticked based on Richard's report?

#2 Updated by Richard Duivenvoorde over 5 years ago

Hi Jonathan, I've just writing a little 'rant' about WCS QGIS and PDOK (our national data service), as all have their quircks, and make live hard for the average QGIS user http://www.qgis.nl/2019/01/20/wcs-qgis-en-pdok/?lang=en

I'm not sure if I should not close this ticket, as I have put some time in it, and it looks like it is the combination of the WCS standard, the data provider, the data type and QGIS that messes things up :-)

QGIS does things in a way that does not play well with the service, and I'm not 100% sure who is to blame for that.

I had a little discussion on the list with Luigi about maybe partly silencing QGIS to not fire the 'probing' requests to such a service. And I'm also trying to create a plugin to show all requests that QGIS is firing, hoping to give dev's and users more insight in all the traffic that is going on...

Could you reproduce the crash? Maybe also with other services?

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