I have a PNG map with just black and white colors, where black is the one pixel border. I want this in vector, or want an easy way to draw 90 degree polygons.

I tried some things from forums but I don't have a solution yet.

enter image description here

closed as unclear what you're asking by Andre Silva, HDunn, xunilk, Vince, PolyGeo Dec 30 '18 at 23:14

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    Welcome to gis.SE. Please take the tour and find out how to write a good question. Give pictures and tell us what you have tried so far. – Stefan Dec 30 '18 at 12:49
  • If you are looking for an open source solution, have a look at GRASS GIS r.thin, r.to.vect and v.generalize commands. All these commands are available from QGIS Processing Toolbox. – Zoltan Dec 30 '18 at 13:18
  • Google image search tells me that this is a map of Hungary. You should be able to find vector files of Hungary's districts online. – Stefan Dec 30 '18 at 13:28
  • These are election constituencies and there aren't any open source vector map. :/ I will try Grass Gis, thanks. – Liszur Dec 30 '18 at 13:34
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    Do you want this to be tied down to a geographical location, or is this just an image processing problem? If it's just an image processing problem then you could use this svg or use Inkscape to trace your png, and alter it as necessary. If you want it to be linked to geographic locations then you will need to find another data source as knowledge of how the image was generated (i.e. the projection) would be required. – Ari Cooper-Davis Dec 30 '18 at 16:06

I offered you GRASS raster to vector conversion, but seeing you map I would propose you an other solution. There are free administrative data for Hungary which contains most of the borders you need. You can find the them at http://www.diva-gis.org/gdata. Select Hungary and administering areas. It contains 168 subregions. I 've georeferenced your png image in QGIS and put together these two layers (raster and vector). overlay of the layers

I would manually digitize the few missing lines with Split feature tool in Advanced digitizing toolbar. It would be less work.

An other source can be the OSM data for Hungary http://download.geofabrik.de/europe/hungary.html It contains much more lines then you necessary.

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