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I am trying to generate a new shapefile in QGIS based on a georeferenced scanned map of colonial powers in Africa and the NaturalEarth country shapes. The overlay of the georeferenced TIFF looks quite ok, and most of the borders still exist today.

How can I combine a) Existing parts of a shape into a new, larger shape? b) Existing parts of a shape with some new borders I draw to make a new shapefile?

Screenshot of georeferenced image

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  • Welcome to gis.stackexchange! Could you add more details about what results you want to generate? Have you tried vectorizing the raster? Do you need attributes from the existing vector layer?
    – underdark ♦
    Jan 9, 2016 at 22:09
  • Vectorizing the raster was the hint I was looking for. Thanks. I did so, and then used the Advanced Digitizing Tools to cut my new shapes together. There was no data in the scanned map, I had to handcode everything. But thanks, your hint was what I needed.
    – Sebastian
    Jan 10, 2016 at 11:35

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You can create vector polygons from your raster by using Raster | Conversion | Vectorize.

The topic is also covered by the QGIS User Guide: http://docs.qgis.org/2.8/en/docs/training_manual/complete_analysis/raster_to_vector.html

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