[geos-devel] Clipping geometries

Paul Meems bontepaarden at gmail.com
Mon Dec 16 01:54:47 PST 2013

Hi List,

We use GEOS with GDAL in our MapWinGIS project (mapwingis.codeplex.com) and
we have some questions about clipping and how it is implemented in GEOS.

I have a polyline shapefile with the USA major roads, most roads overlap
multiple states.
I also have a polygon shapefile with USA states.

When I clip the roads with the states I would expect a polyline as a result
where a road that crosses a state border is clipped resulting in two
Is this the expected behavior and which GEOS methods should I use to
accomplish this?

Now switching the layers. I clip the states with the roads and when a road
crosses the state and starts and ends outside the state the state is
divided into two polygons with the road as the new border.
This might be less common, so I wonder if I can expect from GEOS to handle
this. And again which GEOS methods should I use if this is possible?

Of course I did some searching for documentation, but couldn't find it.
If the documentation explains my questions please give me the url.


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