[postgis-users] New within problem (was:(URGENT BUGFIX (was: two different geometries with the same Astext))

[Miguel de la Fuente]

I think I didn't explain it very well.

what I don't understand is why Within(g1,g2) returns me False while g1
is in fact a segment of g2, so g1 is "within" g2.

WITHIN(g1,g2) returns FALSE

And only because of it is that I added the within functions between
their box2d(), and their geometryfromtext(astext()), and they return
me TRUE as I expected.

WITHIN(BOX2D(g1),BOX2D(g2)) returns TRUE
WITHIN(GEOMETRYFROMTEXT(ASTEXT(g1)),GEOMETRYFROMTEXT(ASTEXT(g2))) returns TRUE




On 7/28/05, strk at refractions.net <strk at refractions.net> wrote:
> By definition within requires NO boundary overlap.
> 
> Within(box2d,box2d) implicitily casts the box2d
> into polygons, and since the polygons boundaries overlap
> I think within() is correctly returning false.
> 
> For MULTILINESTRINGS the boundaries are the endpoints.
> 
> Try:
> 
>  SELECT within(exteriorring(box2d(g1)), exteriorring(box2d(g2)))
> 
> This would return the polygon boundaries as LINESTRINGS
> 
> --strk;
> 
> On Thu, Jul 28, 2005 at 10:38:45AM -0300, Miguel de la Fuente wrote:
> > Thanks Strk, your fix work well with the example I wrote first.
> >
> > But, now I`m still having problems with within().
> >
> > I fix the bug as you see:
> >
> > select postgis_full_version()
> >
> > "POSTGIS="1.0.2" GEOS="2.1.3" PROJ="Rel. 4.4.9, 29 Oct 2004" USE_STATS
> > DBPROC="0.3.0" RELPROC="0.3.0""
> >
> > After that, I found the following error
> >
> > CREATE TABLE mu (
> >    g1 geometry,
> >    g2 geometry
> > );
> >
> > ALTER TABLE public.mu OWNER TO postgres;
> >
> > INSERT INTO mu (g1, g2) VALUES
> > ('0105000000010000000102000000020000001BA43BA50E5A5541A12F8367C80956418284C50C685A5541F12B9D84250A5641',
> > '0105000000010000000102000000050000002246BA2BF05A55418B479267A20956414C8D31C4965A5541C6DC774A450956411BA43BA50E5A5541A02F8367C80956418484C50C685A5541F52B9D84250A56412246BA2BF05A55418B479267A2095641');
> >
> > SELECT
> >             ASTEXT(g1),
> >             ASTEXT(g2),
> >             BOX2D(g1),
> >             BOX2D(g2),
> >             WITHIN(g1,g2),
> >             WITHIN(BOX2D(g1),BOX2D(g2)),
> >             WITHIN(GEOMETRYFROMTEXT(ASTEXT(g1)),GEOMETRYFROMTEXT(ASTEXT(g2)))
> > FROM
> > mu
> >
> > "MULTILINESTRING((5597242.5817652 5777185.61738196,5597600.19955552
> > 5777558.072093))";"MULTILINESTRING((5598144.68324426
> > 5777033.61830319,5597787.06552441 5776661.16356582,5597242.5817652
> > 5777185.61738196,5597600.19955552 5777558.072093,5598144.68324426
> > 5777033.61830319))";"BOX(5597242.5 5777185.5,5597600.5
> > 5777558.5)";"BOX(5597242.5 5776661,5598145 5777558.5)";f;t;t
> >
> > within(g1,g2) return FALSE
> > within(box2d(g1),box2d(g2)) return TRUE
> > within(geometryfromtext(astext(g1)),geometryfromtext(astext(g2))) return TRUE
> >
> > ?????
> >
> > As you see both box2d are well created, and the within() works well
> > with the box2d, but it fails with the multilinestrings.
> > Do you know why?
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