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I would like to have ready polygons (borders) from some .PNG image and use them in QGIS as a shapefile.

My file looks like this:

enter image description here

which is crude raster PDF. My goal is to execute all borders (marked orange) as a simple shepefile polygons, as we know i.e from NUTS1 division.

I converted my PNG file into the vector graphic (SVG) image, thinking that it will be easier to save it in some format.

I used for this purpose the Inkspcape, where I selected option Path -> Trace Bitmap, and then selected colour threshold in order to distinguish these borders with the background. Unfortunately the names also came through, making whole graph difficult to manage.

enter image description here

I started to remove the names manually, but id doesn't make sense, since some of them are sticked to the borders and binded as one layer.

enter image description here

So now I need to find some way to quick separation of the names from the borders, and further I can think about geotagging this SVG graph in QGIS.

However I think, that maybe some less awkward and quicker option is available?

I found something here:

Convert PNG image to Shapefile in QGIS

https://www.safe.com/convert/png/arcgis-shp/

First one doesn't help a lot, and 2nd one requires bigger involvment, which probably is not for free.

I am aware of ready shp administrative (and other) databases, but in this event I need some own.

Is someone able to help?

  • 3
    I think this might be a classic case of spending so much time trying to figure out an automated solution that you end up spending more time than just doing it manually. At this stage my suggestion would be to just georeference it and digitise the polygons. This also means that you're much less likely to end up with geometry errors. Sorry I don't have the solution you're looking for. – TeddyTedTed Dec 12 '19 at 9:51
  • Anyway, thank you for a hint. – MKR Dec 12 '19 at 16:35
  • Forgive me for asking, but are these polling districts? If they are I have good news for you. – nhopton Dec 15 '19 at 14:00
  • No, they represent the 2h drivetime from the address specified (marked by blue marker). – MKR Dec 16 '19 at 9:15
  • Anyhow, you can give me the hint for polling district too, I'll utilise it in the future. – MKR Dec 16 '19 at 9:15

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