Bug report #12143

Wrong measurements when background is from a tiled service

Added by Paolo Cavallini about 9 years ago. Updated about 6 years ago.

Category:Projection Support
Affected QGIS version:2.6.0 Regression?:No
Operating System: Easy fix?:No
Pull Request or Patch supplied:No Resolution:invalid
Crashes QGIS or corrupts data:No Copied to github as #:20337


The scale gets wrong if one adds a tiled baselayer (e.g. Google or OSM via OpenLayers plugin, or via GDAL XML). E.g. at 1:2257 scale, on the video a 100 m line is 4.8 cm; adding a baselayer it becomes 6.9 cm, without changing the scale.
If I load a EPSG:3003 layer, add an OpenLayers plugin layer, the scale gets wrong and the project projection is set at 3857. Changing the projection back to 3003 makes things right again.
Apparently GDAL does not choose the correct zoom level to display the tiles. It does not seem related to the OL plugin, as it behaves the same on the server (seen through LizMap, with the same baselayer).


#1 Updated by Giovanni Manghi almost 7 years ago

  • Easy fix? set to No
  • Regression? set to No

#2 Updated by Paolo Cavallini about 6 years ago

  • Resolution set to invalid
  • Status changed from Open to Closed
  • Description updated (diff)

AFAICU this is related to EPSG:3857 being unsuitable for measurements.

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