Split polygon with linestring

[Paul Meems]

Hi List,

I'm trying to split a polygon with a hole with a linestring.

I use this piece of code:

            var polygonizer = new Polygonizer();

            polygonizer.Add(field.Boundary.Union(splitline));

            var polygons = polygonizer.GetPolygons();

I get 3 polygons back. The top polygon is a simple one.

The bottom polygon has the hole.

I can't figure out which of the 3 polygons is the whole and how to add one of the polygons as a hole.

Doesn't NTS have a method that is already handling this for you?

It seems a rather trivial process.

Thanks,

Paul

Paul Meems 
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[FObermaier]

have a look at SplitPolygon in

https://github.com/NetTopologySuite/NetTopologySuite/blob/master/NetTopologySuite.Samples.Console/Operation/Poligonize/SplitPolygonExample.cs

[reachg...@gmail.com]

Hi,

I ran the above example and didn't understand the output.

As in,

When "POLYGON((0 0, 0 100, 100 100, 100 0, 0 0), (10 10, 90 10, 90 90, 10 90, 10 10))" is split by "LINESTRING(50 -10, 50 110)", I would expect two polygons.

1. POLYGON ((0 0, 0 100, 50 100, 50 90, 10 90, 10 10, 50 10, 50 0, 0 0))

2. POLYGON((50 100, 100 100, 100 0, 50 0, 50 10, 90 10, 90 90, 50 90, 50 100))

but it seems to output only the first one.

What is wrong in my understanding?

Regards,

GreyMan