[OSM-dev] Polygons in OSM don't necessarily comply to simple feature specification
Martijn van Oosterhout
kleptog at gmail.com
Thu Apr 17 10:04:07 BST 2008
On Wed, Apr 16, 2008 at 11:28 PM, Martijn van Exel <mvexel at gmail.com> wrote:
> The only exceptions apparently
> being that self-intersecting polygons are allowed in OSM. He found a
> couple hundred in the Netherlands' OSM data.
Option 1: Fix them
Option 2: Provide a list so someone else can fix them
Option 3: Provide an example so I can look and see if there's an easy
way to detect them
Seriously though, it's probably a bug that should be fixed. The tools
are there, mostly we just don't know how to use them. For example,
while writing the coastline checker I found that libshp has a
RewindObject function which takes a polygon and fixes all the rings.
Neither my program nor mapnik cared either way, but other products may
not be so lucky.
FWIW, self-intersecting polygons generally don't render well, so some
examples would give an idea of what to look for.
Have a nice day,
Martijn van Oosterhout <kleptog at gmail.com> http://svana.org/kleptog/
More information about the dev