[geos-devel] Re: TopologyException: found non-noded intersection

[G. Allegri]

Thanks Martin.
I see that jts 1.11 works fine on a subset of my dataset. I have
hundreds of thousands od polygons to merge... I have to find the way
to read them to pass the collection to JTS without receiving
java.lang.OutOfMemoryError (just happened!).
What do you suggest to build the collection needed by CascadedUnion
without havind to create a huge Collection of geometries?

I will take a look at JEQL. Thanks for the hint, I didn't know it...

Giovanni

2010/6/22 G. Allegri <giohappy at gmail.com>:
> I'm using Postgis 1.5.1 to compute a Union on a quite large
> multipolygons dataset (some hundreds of thousands of features), but
> I'm facing the following error:
>
> NOTICE:  TopologyException: found non-noded intersection between
> LINESTRING (1.7318e+006 4.77959e+006, 1.7318e+006 4.77958e+006) and
> LINESTRING (1.7318e+006 4.77958e+006, 1.73174e+006 4.77954e+006) at
> 1.7318e+006 4.77958e+006
>
> ERROR:  GEOS union() threw an error!
>
> I know it's a known issue, but I haven't been able to find a good,
> replicable, solution. The input geometries result valid (in simple
> feature meaning).
> What is causing this? I have overlapping polygons, but I thought the
> cascaded union algorithm computed the necessary noding on the
> linestrings.
> I've supposed it depends on tolerances/precision model, but I don't if
> it makes sense and how, eventually, tune it.
>
> Thanks a lot,
> Giovanni
>