[OSM-talk] NYPL / map-vectorizer - An open-source map vectorizer

andrzej zaborowski balrogg at gmail.com
Tue Jan 7 20:29:36 UTC 2014


On 7 January 2014 14:35, Christoph Hormann <chris_hormann en gmx.de> wrote:
> On Monday 06 January 2014, Maurizio Napolitano wrote:
>> The lab of the New York Public Library created this software
>> to automate and extract gis data from scanned maps
>> http://www.gislounge.com/automating-extracting-gis-data-scanned-maps/
>
> Note for vectorizing buildings there have also been several
> demonstrations based on potrace - which meanwhile features a GeoJSON
> backend that simplifies the process:

The problem with potrace is that it needs exact colours without the
imperfections of paper drawings and scanner noise.  I imagine the NYPL
tool is better adapted to scanned material.

I've used modified potrace to digitize cadastre data for one city
(potrace was modified to deal with huge tiled images), but later wrote
a dumb python vectoriser that outputs .osm
(https://github.com/balrog-kun/vectoriser), which has similar
limitations to potrace but it can deal with unfilled outlines and I'd
like it to detect line thickness as a next step (which sometimes
reflects building attributes).  Unfortunately it's currently tied to a
specific input tile format.  Neither potrace nor my code properly
understands dashed lines which needed a lot of manual work.

Cheers



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