I'll check for invalid polygons and will get back to you. Thanks a lot, JP
On Sun, Apr 13, 2014 at 2:52 PM, Mike Toews <mwto...@gmail.com> wrote: > > On 14 Apr 2014 04:21, "Juan Pablo Caram" <jpca...@gmail.com> wrote: > > > > Hi Mike, > > I understand the basic concept of a union and resulting type, but how > can the union of polygons result in anything but polygons? > > Thanks, > > JP > > For example, given the range of incomplete coordinates in your example, > the two polygons appear to be disjoint, thus the result is > GEOMETRYCOLLECTION EMPTY. Is there any specific example where a polygon > overlap was expected? Sometimes invalid geometries muddle with these > algorithms that may yield unexpected results. > > -Mike > Hi Mike, > I understand the basic concept of a union and resulting type, but how can > the union of polygons result in anything but polygons? > Thanks, > JP > > > On Sun, Apr 13, 2014 at 5:56 AM, Mike Toews <mwto...@gmail.com> wrote: > >> On 13 April 2014 16:56, Juan Pablo Caram <jpca...@gmail.com> wrote: >> > Hi, >> > Is this at all possible? The GeometryCollection has a LineString! >> >> Sure, this is possible. A union can return any type of geometry, from >> GEOMETRYCOLLECTION EMPTY to POINT to anything else. If the result is a >> LINESTRING, then the union of the two geometries share a boundary. If >> it is in a GEOMETRYCOLLECTION, then there is a mixture of types in the >> same result, such as POINT and POLYGON parts. All these are possible, >> and not so strange when you look at them drawn out. >> >> -Mike >> _______________________________________________ >> Community mailing list >> Community@lists.gispython.org >> http://lists.gispython.org/mailman/listinfo/community >> > > > _______________________________________________ > Community mailing list > Community@lists.gispython.org > http://lists.gispython.org/mailman/listinfo/community > > > _______________________________________________ > Community mailing list > Community@lists.gispython.org > http://lists.gispython.org/mailman/listinfo/community > >
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