different built-in tools calculate inconsistent polygon areas

[qgib]

Author Name: Alister Hood (@AlisterH)
Original Redmine Issue: 4252

Redmine category:projection_support
Assignee: Magnus Homann

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• When using the "measure area" tool, there is an "ellipsoidal" checkbox option. If this is unchecked, a slightly different area is reported, which I think I have seen called the "planimetric" area.
• The "Identify results" for polygons include a "Derived" area. This area is the "ellipsoidal" area.
• The field calculator can also report the area of a polygon. This area is always the "planimetric" area.

I think this behaviour should be tidied up:

• either ellipsoidal or planimetric (I'm not sure which one) measurements should be default everywhere.
• assuming both types of measurement are actually useful, then it should be possible everywhere to use either type. This could be done by a single global or project preference which controls the results for all three tools, or it could be implemented separately for each tool. I don't know which approach would be best.

[qgib]

Author Name: Paolo Cavallini (@pcav)

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See also #14348 and #14529

[qgib]

Author Name: Giovanni Manghi (@gioman)

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• fixed_version_id was configured as Version 1.7.4

[qgib]

Author Name: Alister Hood (@AlisterH)

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Also see #13356 I think.

[qgib]

Author Name: Giovanni Manghi (@gioman)

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• fixed_version_id was changed from Version 1.7.4 to Version 2.0.0

[qgib]

Author Name: Alister Hood (@AlisterH)

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Note that the "export geometry columns" feature in ftools is now capable of calculating ellipsoidal areas, so I guess people should be encouraged to use that tool. It is a lot slower though.

[qgib]

Author Name: Magnus Homann (@homann)

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• assigned_to_id was configured as Magnus Homann

[qgib]

Author Name: Magnus Homann (@homann)

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All except field calculator should be consitent now. Work is ongoing.

[qgib]

Author Name: Alister Hood (@AlisterH)

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Also see #12462 and possibly #13182

[qgib]

Author Name: Pirmin Kalberer (Pirmin Kalberer)

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• fixed_version_id was changed from Version 2.0.0 to Future Release - Nice to have

[qgib]

Author Name: Nyall Dawson (@nyalldawson)

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Fixed in changeset "4094bae960a8521eca6dfe281408ae2e9ad773be".

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• status_id was changed from Open to Closed