Is there a way to extract polygon lines from a map loaded as a .tiff file on QGIS? The original map (see below) of Venice is a scan from a book and has all the lines I need (they mark historical parishes in the city), but it would take to long to manually trace them. I need each parish to be its own entity/polygon.

This image is not georeferenced, and I don't need it to be right now actually. I just find it useful to work on QGIS when dealing with maps.

enter image description here

  • If you're comfortable with Python. You can use an edge detection algorithm with scikit-image. – Aaron Feb 10 '17 at 17:26
  • This may be helpful: opensourcegisblog.blogspot.com/2014/08/… – Aaron Feb 10 '17 at 17:37
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    i suspect the text and stippling would make automated feature extraction difficult. probably easier to georeference and trace manually over it. – Steven Kay Feb 10 '17 at 19:07
  • I was trying to avoid that since that would be a lot of tracing... Thanks though! – darj Feb 14 '17 at 17:06

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