Bug report #21489

Delayed prompting for CRS datum transformation

Added by Andy Harfoot almost 5 years ago. Updated almost 5 years ago.

Status:In Progress
Assignee:Nyall Dawson
Category:Projection Support
Affected QGIS version:3.6.0 Regression?:Yes
Operating System: Easy fix?:No
Pull Request or Patch supplied:No Resolution:
Crashes QGIS or corrupts data:No Copied to github as #:29306


When the QGIS CRS setting 'ask for datum transformation if several are available' is enabled, the prompt does not appear when adding data requiring a datum transformation to match the project CRS, with the default transform seemingly being used. When the layer properties of the newly added layer are opened, the prompt appears, and if a non-default transform is selected, only then is it applied to the data. This is in contrast to 2.18.28 where the prompt appears immediately on adding the dataset to the map.

This may be related to issue #21275

Steps to reproduce:

  1. Enable 'ask for datum transformation if several are available' prompt in QGIS settings (CRS tab)
  2. Load BNGdata polygon layer into a blank project, and set the project CRS to EPSG:27700
  3. Load WGS84data points into the project - no transformation prompt appears, points align with polygon vertices
  4. Open the WGS84 layer's properties. The transformation prompt appears before the properties dialog opens.
  5. Choose datum transformation 4, EPSG:1195, apply and observe that the points are now displaced from the polygon vertices.

TransformationPrompt.zip (5.77 KB) Andy Harfoot, 2019-03-05 10:33 PM


#1 Updated by Giovanni Manghi almost 5 years ago

  • Regression? changed from No to Yes
  • Operating System deleted (Win 10 x64)
  • Priority changed from Normal to High

Confirmed here on Linux too.

#2 Updated by Nyall Dawson almost 5 years ago

  • Assignee set to Nyall Dawson
  • Status changed from Open to In Progress

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