[geos-devel] geos_c question from new user

Stephen Woodbridge woodbri at swoodbridge.com
Thu Dec 22 09:17:30 EST 2005

Hi all,

I'm making my first attempt at using the GEOS C api. Basically, what I 
am trying to do is take a bunch of linestrings, polygonize them, extract 
the polygons and write them to a shapefile. This seems all pretty 
straight forward to do using GEOS.

My questions are:

1. How do I decompose a MULTIPOLYGON?

It appears the GEOSGetNumGeometries() and GEOSGetGeometryN() only work 
on collections.

2. Is a POLYGON only a single ring and a MULTIPOLYGON a single exterior 
ring and some N interior rings? but multiple exterior rings would always 
be returned from polygonize as a COLLECTION? If this is true, then I see 
how to do it.


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