Re: [Geotools-gt2-users] JTS/Graph Question

[David Z. <dav...@gm...>]

Check out JCS (http://www.vividsolutions.com/jcs/) - there are a couple
graph structure tools. We've successfully built a polygonal coverage
manipulation model over JCS, so you should be able to do roughly the same
thing - just ignore the polygon faces and visualize how the polygon rings
are represented as a graph structure, should be similar to what you're
looking for.

David

On Wed, Feb 27, 2013 at 6:04 PM, brandon willard
<bra...@gm...>wrote:

> Looking over my problem again, the result of a large union (e.g. using
> Geometry.union or CascadePolygonUnion) does produce the output lines I
> need, but then I lose any graph-like structure that would associate the
> input lines with those union-produced lines.  (I wasn't clear about that
> requirement, sorry)
>
> How can I produce/maintain a relationship between the input lines and the
> "broken down" lines the union produces, without brute force checking
> overlaps between the two?
>
>
> On Wed, Feb 27, 2013 at 9:15 AM, Justin Deoliveira <jde...@op...>wrote:
>
>> Hey Brandon,
>>
>> I am not 100% sure i undersand what you are looking for. Are you looking
>> to node the graph at intersections and line string endings?
>>
>> I am not sure if this will be what you are looking for but there is a
>> very cool effect that can be achieved with JTS. Basically take all the line
>> strings and join them into one multi linestring. Then union that multi
>> linestring with a single point that exists on it. The result is a multi
>> linestring where all the individual linestrings are properly noded at
>> intersections.
>>
>> -Justin
>>
>>
>> On Tue, Feb 26, 2013 at 9:47 AM, brandon willard <
>> bra...@gm...> wrote:
>>
>>> Hello,
>>>
>>> I'm working with a bunch of LineStrings that mostly overlap, and I would
>>> like to find a way to build a graph, or manipulate the geometries, so that
>>> it ends up with vertices from the points at which they stop overlapping.
>>> E.g. L1 =  a->...->b->c, L2 = a->...->b->d and get vertices (a, b, c, d)
>>>
>>> I realize that it's possible to do this with a combination of JTS
>>> intersections/differences and whatnot, but I'm working with a lot of a
>>> LineStrings and was hoping there was something specifically for this that I
>>> passed over.
>>>
>>>
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>>>
>>
>>
>> --
>> Justin Deoliveira
>> OpenGeo - http://opengeo.org
>> Enterprise support for open source geospatial.
>>
>
>
>
> ------------------------------------------------------------------------------
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