[postgis-users] strange beahviuors by GEOS

strk strk at keybit.net
Wed Mar 10 10:50:11 PST 2004


The bug found in pgsql2shp has been fixed.
It created shapefiles records with less vertex then required
when facing Multipolygon geometries dumped in WKB format (the default)

--strk;


On Wed, Mar 10, 2004 at 07:32:47PM +0100, strk wrote:
> On Tue, Feb 24, 2004 at 09:42:24AM -0000, Darren Houston wrote:
> > 
> > Hello James,
> > 
> > Well, I loaded and dumped your data. This is what I got.
> > 
> > The loader works fine (PostGIS CVS from February 22, 2004).
> > The dumper does not work, gives the mangled polygons just like nuts2 (PostGIS
> > CVS from February 22, 2004).
> > The dumper from PostGIS 0.7.5 works fine, gives a polygon like nuts2_scotland.
> > 
> > Therefore, I would say there is a bug in the current PostGIS dumper. You can
> > download an earlier version of pgsql2shp, or download PgArc which allows you to
> 
> I've found that making pgsql2shp work with WKT instead of WKB
> solves the problem. You have to undef USE_WKB in pgsql2shp.c
> and recompile it.
> 
> Still, I didn't find the bug yet.
> 
> --strk;
> 
> > connect to and dump shapes from PostgreSQL into ArcView 8.X. See
> > http://sourceforge.net/projects/pgarc/
> > 
> > Hope this helps,
> > 
> > James S reid <james.reid at ed.ac.uk> said:
> > 
> > >
> > > ------=_NextPart_001_0DE5_01C3FAB5.4DE25910
> > > Content-Type: text/plain;
> > > 	charset="iso-8859-1"
> > > Content-Transfer-Encoding: quoted-printable
> > >
> > > hi again - thanks for replying - I had a thought overnight and decided =
> > > to check the input data by dumping the loaded shapefiles and its heer =
> > > the problem lies - the correct number of recorsd are reported in teh =
> > > tables and by the loade/dumper but taking the orignal shapefile, loading =
> > > it then dumping it to a new shapefile reveals that the .shp itself is =
> > > funny and causes the generic 'segmentation violation' in av3.1 and has =
> > > lots of offshoots and strange polys in AV8. ive attached a zipfielof teh =
> > > original shapefile and the dumped one (nuts2.shp).
> > >
> > > I guess its to do with being a multipolygon with holes and islands but =
> > > Im not sure how to proceed to get the data loaded properly ???
> > >
> > > cheers
> > >
> > > james
> > >   ----- Original Message -----=20
> > >   From: Tyler Mitchell=20
> > >   To: PostGIS Users Discussion=20
> > >   Sent: Monday, February 23, 2004 6:27 PM
> > >   Subject: Re: [postgis-users] strange beahviuors by GEOS
> > >
> > >
> > >
> > >   > hi - Im testing a polygon in polygon selection using the within() =
> > > operator
> > >   > on two tables and have come across some odd return sets. =
> > > essentially, I can
> > >   > confirm the 'proper' results in arcview (booh hiss) but postgis =
> > > (using geos)
> > >   > returns 1 less poly for no reason that i can see!
> > >
> > >   Hi James,=20
> > >   Could you show us the SQL you are using?  Ideally a small screenshot =
> > > showing the map data would be nice too.
> > >
> > >
> > > -------------------------------------------------------------------------=
> > > -----
> > >
> > >
> > >   _______________________________________________
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> > >   postgis-users at postgis.refractions.net
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> > >
> > > ------=_NextPart_001_0DE5_01C3FAB5.4DE25910
> > > Content-Type: text/html;
> > > 	charset="iso-8859-1"
> > > Content-Transfer-Encoding: quoted-printable
> > >
> > > <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
> > > <HTML><HEAD>
> > > <META http-equiv=3DContent-Type content=3D"text/html; =
> > > charset=3Diso-8859-1">
> > > <META content=3D"MSHTML 6.00.2800.1400" name=3DGENERATOR>
> > > <STYLE></STYLE>
> > > </HEAD>
> > > <BODY bgColor=3D#ffffff>
> > > <DIV><FONT face=3DArial size=3D2>hi again - thanks for replying - I had =
> > > a thought=20
> > > overnight and decided to check the input data by dumping the loaded =
> > > shapefiles=20
> > > and its heer the problem lies - the correct number of recorsd are =
> > > reported in=20
> > > teh tables and by the loade/dumper but taking the orignal shapefile, =
> > > loading it=20
> > > then dumping it to a new shapefile reveals that the .shp itself is funny =
> > > and=20
> > > causes the generic 'segmentation violation' in av3.1 and has lots of =
> > > offshoots=20
> > > and strange polys in AV8. ive attached a zipfielof teh original =
> > > shapefile and=20
> > > the dumped one (nuts2.shp).</FONT></DIV>
> > > <DIV><FONT face=3DArial size=3D2></FONT> </DIV>
> > > <DIV><FONT face=3DArial size=3D2>I guess its to do with being a =
> > > multipolygon with=20
> > > holes and islands but Im not sure how to proceed to get the data loaded =
> > > properly=20
> > > ???</FONT></DIV>
> > > <DIV><FONT face=3DArial size=3D2></FONT> </DIV>
> > > <DIV><FONT face=3DArial size=3D2>cheers</FONT></DIV>
> > > <DIV><FONT face=3DArial size=3D2></FONT> </DIV>
> > > <DIV><FONT face=3DArial size=3D2>james</FONT></DIV>
> > > <BLOCKQUOTE=20
> > > style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; =
> > > BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
> > >   <DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV>
> > >   <DIV=20
> > >   style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
> > > black"><B>From:</B>=20
> > >   <A title=3DTMitchell at lignum.com =
> > > href=3D"mailto:TMitchell at lignum.com">Tyler=20
> > >   Mitchell</A> </DIV>
> > >   <DIV style=3D"FONT: 10pt arial"><B>To:</B> <A=20
> > >   title=3Dpostgis-users at postgis.refractions.net=20
> > >   href=3D"mailto:postgis-users at postgis.refractions.net">PostGIS Users=20
> > >   Discussion</A> </DIV>
> > >   <DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Monday, February 23, 2004 =
> > > 6:27=20
> > >   PM</DIV>
> > >   <DIV style=3D"FONT: 10pt arial"><B>Subject:</B> Re: [postgis-users] =
> > > strange=20
> > >   beahviuors by GEOS</DIV>
> > >   <DIV><BR></DIV><BR><FONT size=3D2><TT>> hi - Im testing a polygon =
> > > in polygon=20
> > >   selection using the within() operator<BR>> on two tables and have =
> > > come=20
> > >   across some odd return sets. essentially, I can<BR>> confirm the =
> > > 'proper'=20
> > >   results in arcview (booh hiss) but postgis (using geos)<BR>> =
> > > returns 1 less=20
> > >   poly for no reason that i can see!<BR></TT></FONT><BR><FONT =
> > > size=3D2><TT>Hi=20
> > >   James,</TT></FONT> <BR><FONT size=3D2><TT>Could you show us the SQL =
> > > you are=20
> > >   using?  Ideally a small screenshot showing the map data would be =
> > > nice=20
> > >   too.</TT></FONT>
> > >   <P>
> > >   <HR>
> > >
> > >   =
> > > <P></P>_______________________________________________<BR>postgis-users=20
> > >   mailing=20
> > >   =
> > > list<BR>postgis-users at postgis.refractions.net<BR>http://postgis.refractio=
> > > ns.net/mailman/listinfo/postgis-users<BR></BLOCKQUOTE></BODY></HTML>
> > >
> > > ------=_NextPart_001_0DE5_01C3FAB5.4DE25910--
> > >
> > 
> > 
> > 
> > 
> > --
> > Darren Houston
> > 
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