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I'm trying to learn how to work a bit with Qgis for a part of a university work, and I'm facing some difficulties with an old map, and setting it up with the right coordinates.

I have some old maps from a part of Portugal, and when I added them in Qgis all together, they fitted well and were all well ordered, so I started to mark some spots on them.

After, when I tried to add a Openmap over it, I saw that they didn't match, and the old maps were over Africa (and maybe with the wrong scale).

Is there any way of transposing the old maps and the marked points (a .shp file) to the right coordinates? I've spent quite some time marking all those spots, and I needed to mark them over the old maps, and have them fit in the right spot of the OpenStreetMap.

I've tried multiple CRS configs, moving them... But I can't seem to figure it out how to do this. Anyone can give me some lights on how to set the old maps and the .shp file on the right spot?

I can provide the files, and all the info needed

  • How did you add the maps to QGIS, did you georeference them? – Knightshound Nov 4 '16 at 10:08
  • It's a .sid file, I just moused them over to Qgis, and selected the CRS WGS 84, like it is in the rest of the project. Also there are .map files for each .sid saying for example "European 1950 (Portugal),, 0.0000, 0.0000,WGS 84" – RetronWarz Nov 4 '16 at 10:13
  • It is always useful to include in the question some sample points (or extent) of data where you're unsure of the coordinate reference system. It makes it easier for others to try to identify what it is. – mkennedy Nov 4 '16 at 15:11
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Well I guess this could work:

  • Open old map in Raster > Georeferencer.
  • Use characteristic points on OpenStreetMap and "old" map for georeferencing.
  • Now your "old" map is on the correct position.
  • Enable editing mode on the point layer.
  • Select all points and move them into correct position.

This is not a perfect solution, but it should be satisfactory for many applications.

If you need more information about georeferencing in qgis, check this tutorial: https://www.youtube.com/watch?v=7ykSGrO6l1s&index=15&list=PLNCPalajQvg7wQvzf3fM8fOZ5lMKl86Q4

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