CGAL users discussion list

[Marcos Dione <>]

On Tue, Aug 30, 2016 at 05:28:20PM +0200, Sebastien Loriot (GeometryFactory) 
wrote:
> Expr: aPoly.is_simple() || !"The input polygon is not simple."
> File: include/CGAL/create_straight_skeleton_2.h

    python-shapely[1], which is built on top of GEOS, just like PostGIS[3],
disagrees:

In [1]: import shapely.wkt

In [2]: s= open('121897178.wkt').read()

In [3]: sh= shapely.wkt.loads(s)

In [4]: sh.is_simple
Out[4]: True

    A visual inspection of the feature does not reveal any crossing of
its (only) polygon, but the lines are really close. i see that CGAL does
not use any external lib for its internal representation, maybe the bug
is around there? Or, most probably, I'm making a mistake at some point.

    Cheers,

        -- Marcos.

--
[1] http://toblerity.org/shapely/manual.html

[2] https://trac.osgeo.org/geos/

[3] 
http://postgis.net/docs/manual-2.2/postgis_installation.html#install_requirements
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