[OSM-dev] ogr2poly.py with buffering and simplifying
frederik at remote.org
Mon Dec 5 19:48:35 GMT 2011
On 12/05/2011 07:29 PM, Josh Doe wrote:
> I created a Python script to convert OGR supported files (Shapefile
> and many others) to the polygon filter file format used by Osmosis and
> other tools. It will optionally buffer and simplify polygons for you.
> You can buffer point and line features to create polys as well.
I have something similar done in C but always found it too fragile to share:
It takes a "relation/xxx/full" OSM as input, and writes out an OSM file
again (which you can view/modify in JOSM then convert to poly).
The clou with this one is that it will buffer and simplify but it will
guarantee that the original polygon is always fully contained in the
result - i.e. it will never cut off an edge through over-eager
simplification. This is done not by clever algorithms but by simply
grinding through a number of buffer and simplification parameters until
the desired result is found.
I have found this to work well for polygon generation, except the glitch
http://www.osgeo.org/pipermail/geos-devel/2011-May/005208.html. If you
can solve *that* problem then I'll even consider installing Python.
Frederik Ramm ## eMail frederik at remote.org ## N49°00'09" E008°23'33"
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