Re: [Jts-topo-suite-user] Split polygon with polyline and merge polygons.

[Landon B. <sun...@gm...>]

Martin Herich:

Are you trying to split multiple polygons crossed by the same polyline, or
just a single polygon?

Landon


On Thu, Oct 24, 2013 at 7:46 AM, Martin Davis <mtn...@te...> wrote:

>  Martin, sorry for the slow reply.
>
> There is currently no function in JTS which splits a polygon with a
> polyline, unfortunately.  It's high on the wishlist, but there's no ETA
> right now. Your approach is about the best possible right now, but yes, you
> will have to identify resultant polygons which do not have a parent polygon
> (using a point-in-polygon test is the usual method to do this).
>
> And unfortunately there is currently no capability in JTS to provide a
> distance tolerance for geometric operations.  This would be nice to have
> for predicates and overlay operations.  In the meantime, you might try
> looking at the GeometrySnapper class [1], which can be used to snap one
> geometry to another.  It's not 100% robust so you need to be a bit careful
> of the output, but it should work in many situations with a small tolerance.
>
> [1]
> http://tsusiatsoftware.net/jts/javadoc/com/vividsolutions/jts/operation/overlay/snap/GeometrySnapper.html
>
>
> On 10/16/2013 7:22 AM, Martin Herich wrote:
>
>  Hi,****
>
> I have got one question we are testing .NET Version of JTS if it fits our
> tasks. We need to divide any polygon with a polyline. I think we can use
> the function overlaysnapround which with the precision 100000 give us
> appropriate results. The only problem is that we have to always filter the
> new polygons to identify those which doesn’t intersect with the original
> one (polygon number 1 on the picture). Is there any other function that
> simply splits the polygon with polyline?****
>
>
> ****
>
> ** **
>
> ** **
>
> The second task is an opposite – merging two or more polygons together.
> The problem is when we use union, the polygons hast to overlap to merge.**
> **
>
> Is there any possibility to tell JST that a certain distance between two
> points should be taken as 0? We don’t want to reduce the precision as it
> reduce the precision on all coordinates and that changes the whole geometry.
> ****
>
>
> ****
>
>
>
>
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