On Thu, Sep 29, 2011 at 01:22:11PM +0200, Szymon Guz wrote:
> On 29 September 2011 11:37, Sandro Santilli <s...@keybit.net> wrote:
>
> > On Thu, Sep 29, 2011 at 11:29:51AM +0200, Szymon Guz wrote:
> > > On 29 September 2011 11:20, Sandro Santilli <s...@keybit.net> wrote:
> > > > On Thu, Sep 29, 2011 at 11:14:52AM +0200, Szymon Guz wrote:
> > > > >
> > > > > this works OK, returns something:
> > > > >
> > > > > SELECT ... FROM ... WHERE
> > > > > st_intersects(
> > > > > geometry,
> > > > > st_geomfromtext('POINT(3 50)', 4326)
> > > > > );
> > > > >
> > > > > but this returns nothing:
> > > > >
> > > > > SELECT ... FROM ... WHERE
> > > > > st_intersects(
> > > > > geometry,
> > > > > st_geomfromtext('POINT(3 50, 3 50 )', 4326)
> > > > > );
> > > >
> > > > The second should raise an exception due to malformed WKT being used.
> > > > Doesn't it ?
> > >
> > > The second raises exception only if there is exactly one point. When
> > there
> > > are more points it works OK:
> > >
> > > SELECT st_geomfromtext('LINESTRING(3 50)', 4326)
> > > ERROR: geometry requires more points
> > > HINT: "LINESTRING(3 50)" <-- parse error at position 17 within geometry
> > >
> > > SELECT st_astext(st_geomfromtext('LINESTRING(3 50, 3 50)', 4326))
> > >
> > > 'LINESTRING(3 50,3 50)'
> >
> > Yes, but you wrote 'POINT(3 50, 3 50)' in your first mail :)
> >
> > Anyway, you're now saying that while POINT(3 50) is reported
> > to intersect something, LINESTRING(3 50, 3 50) isn't. Correct ?
> > Can you provide literal data showing this discrepance ?
> > That is, a query where both operands are in WKT form ?
> >
> > --strk;
> >
>
> Oh yes, sorry, I meant 'LINESTRING( 3 50, 3 50)' :)
>
> I managed to replicate the error like this:
...
>
> CREATE TABLE g2(geometry geometry);
>
> insert into g2(geometry)
> SELECT ST_Buffer(
> ST_GeomFromText('POINT(3 50)', 4326),
> 50, 'quad_segs=8'
> );
// TRUE:
select st_intersects(geometry, st_centroid(geometry)) from g2;
// FALSE:
select st_intersects(geometry,
st_makeline(
st_centroid(geometry),
st_centroid(geometry)
)) from g2;
// TRUE:
select st_intersects(geometry,
st_makeline(
st_centroid(geometry),
st_translate(st_centroid(geometry), 1e-6, 0)
)) from g2;
Interesting. This is against GEOS 3.3.1.
True, the linestring is invalid, but doesn't give wrong answer when
compared to a point.
ST_MakeValid will fix that line for you, turning into a point.
--strk;
() Free GIS & Flash consultant/developer
/\ http://strk.keybit.net/services.html
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