Label: line geometry labels drawn to wrong location when CRS transformed

[qgib]

Author Name: Simo Aro (Simo Aro)
Original Redmine Issue: 10526
Affected QGIS version: master
Redmine category:map_canvas

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Steps to reproduce the issue: Create new project. Drag attached GeoJSON file to layers panel. Add labels to layer with field 'name'.

Labels are diaplayed properly, all with the same distance from the line geometry.

Next, click the "CRS status" icon on the lower right corner, the "Project properties | CRS" window opens. Now, click "Enable 'on the fly' CRS transformation" checkbox and choose any transformation from the list, such as "Google Mercator" (ESPG:900913) or "ETRS89 / ETRS-TM35FIN" (ESPG:3067). Now click "OK".

The end result is that some labels are now displaced from the line geometry they belong to (see attached screen capture - the issue is evident). This issue seems to have greater effect the longer the line geometry is and the greater the zoom level is.

This bug seems to affect at least versions 2.2.0-Valmiera and 2.3.0-Master

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• screencapture.png (Simo Aro)
• ROUTES_2013.json (Simo Aro)
• 53.png (Giovanni Manghi)
• 05.png (Giovanni Manghi)
• 38.png (Giovanni Manghi)
• EPSG4326.png (Simo Aro)
• EPSG3047.png (Simo Aro)
• 34.png (Giovanni Manghi)
• 57.png (Giovanni Manghi)

[qgib]

Author Name: Giovanni Manghi (@gioman)

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On Linux/master I cannot seen any particular difference, see attached images

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• status_id was changed from Open to Feedback
• 7397 was configured as 53.png
• 7399 was configured as 38.png
• 7398 was configured as 05.png
• category_id was configured as Labelling

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• 53.png (Giovanni Manghi)
• 38.png (Giovanni Manghi)
• 05.png (Giovanni Manghi)

[qgib]

Author Name: Simo Aro (Simo Aro)

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Giovanni Manghi: This seems to affect certain parts of the world more.

Please try this location (WGS84):

Coordinate: 29.3,62.52 at scale 1:25,000

After pointing to that location, then switch to some other CRS, such as "ETRS89 / ETRS-TM35".

Please see attached screen captures for "before" and "after" effect.

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• 7405 was configured as EPSG3047.png
• 7404 was configured as EPSG4326.png

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• EPSG3047.png (Simo Aro) - After
• EPSG4326.png (Simo Aro) - Before

[qgib]

Author Name: Giovanni Manghi (@gioman)

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Simo Aro wrote:

Giovanni Manghi: This seems to affect certain parts of the world more.

Please try this location (WGS84):

Coordinate: 29.3,62.52 at scale 1:25,000

After pointing to that location, then switch to some other CRS, such as "ETRS89 / ETRS-TM35".

Please see attached screen captures for "before" and "after" effect.

actually I think there is something fishy with the data or with the qgis reprojection, see attached images:

*) I made a copy of you json layer as a shape and transformed it to 3067 along the way. In the picture you see that the project is in 4326 and reprojection is on, so the two versions of the same layer are expected to overlap, and there are lines that do, but others don't.

*) if you then change the project CRS to 3067 and eave reprojection ON you will see that the labels (of your original json layer) are placed where the lines of the shapefile are.

So my first gut feeling is that the labels are placed in the right place, but I can't understand why saving your layer in another one with a different CRS then result in just a few features to be in the same place as the original ones (when reprojection is ON).

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• 7410 was configured as 57.png
• os_version was changed from 10.8.5 to
• operating_system was changed from Mac OS X to
• 7409 was configured as 34.png

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• 57.png (Giovanni Manghi)
• 34.png (Giovanni Manghi)

[qgib]

Author Name: Giovanni Manghi (@gioman)

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• category_id was changed from Labelling to Map Canvas

[qgib]

Author Name: Giovanni Manghi (@gioman)

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• status_id was changed from Feedback to Open

[qgib]

Author Name: Giovanni Manghi (@gioman)

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• regression was configured as 0
• easy_fix was configured as 0

[qgib]

Author Name: Giovanni Manghi (@gioman)

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End of life notice: QGIS 2.18 LTR

Source:
http://blog.qgis.org/2019/03/09/end-of-life-notice-qgis-2-18-ltr/

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• resolution was changed from to end of life
• status_id was changed from Open to Closed