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I'm trying to duplicate and flip a bunch of features you can see on yellow in order to complete the right part of this map (Abattoirs de Montmartre in Paris, 1850):

enter image description here

I tried with QGIS docs with no success, then with this plugin Shape Tools but it flips each features with their own center as origin 🤪 As you can see here:

enter image description here

Is there a way to flip the full layer or full group and to chose the origin?

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My approach would be like this. You need therefor additionally the advanced digitizing. This comes with QGIS, but you have propably to activate the toolbar.

  1. Create a temporary layer with type polygon. It is default ready for editing.
  2. Select the relevant polygons from your original layer, copy them and insert into the temp layer.
  3. Make sure all polygons on the temp layer are selected and merge them into a multipolygon with the function from the advanced digitizing.
  4. Now flip this selected multipolygon with the shape tools horizontally.
  5. After that you can rotate and move the multipolygon with the functions in the advanced digitizing.
  6. When all is correct positioned, copy it and insert back to your original layer.

If your original Layer has the type multipolygon you have to add a step between 5. and 6.. You must split the multipolygon to singles. This could be done with the plugin "Digitizing tools". It has such a function.

Hopefully this helps.

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  • Thank you ! The missing step was definitly 3. "merge into multipolygon" I had no knowledge of this type 🙏 – Florian Boudot May 9 '20 at 20:52
  • You're welcome. Glad, that it worked for you. – Michael May 10 '20 at 3:38
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Geodesic Flip and Rotate

you will need to do a select and move after this to align the the objects after.

(using scratch/virtual layers here)

enter image description here

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