[postgis-devel] different result ST_Tesselate from invalid polygon that ST_IsValid says is valid

[Nicklas Avén]

Thanks Martin!
I realize you of course are right when looking closer on it. It was all
those intersections between the holes and boundary that made me think
so.But it is actually 3 holes :-)
Then I guess that the error message comes from libcgal and probably
boost when running st_tesselate.
So then my confusion moves to why ST_Tesselate works on 1 computor but
not on another with same OS, same versions of PostGIS code.
I also don't fully understand the error message:ERROR:  Polygon is
invalid : interior is not connected
Since it is all integer values I don't understand that there should be
any machine dependent differences when judging validity.
This is about the packaging of TilelessMap. I have to find a better way
of doing the triangulation since, in the end I don't want the triangle
coordinates but just their index in the boundary.
It is the ugly scripts here that I need to find a way to handle invalid
geometries and ugly geometries like this.https://github.com/TilelessMap
/pg_tilelessThanks
Nicklas


On Tue, 2018-04-24 at 12:39 -0700, Martin Davis wrote:
> It's ugly, but it is valid according to SFS rules (which is what
> JTS/GEOS/PostGIS implement).
> Why do you think it is not valid?
> 
> On Tue, Apr 24, 2018 at 11:48 AM, Nicklas Avén <nicklas.aven at jordogsk
> og.no> wrote:
> > Hello
> > 
> > 
> > 
> > I have an ugly polygon, presented as wkt here below.
> > 
> > 
> > 
> > It is really ugly, and from what I understand it has
> > selfintersection
> > 
> > and other things taht I expected ST_Isvalid to react on.
> > 
> > 
> > 
> > But ST_Isvalid let's it through.
> > 
> > 
> > 
> > And on 2 of my PostGIS installations ST_Tesselate gives a
> > reasonable
> > 
> > answer. But on a third installation on a virtual machine at Linode
> > I
> > 
> > get an error message which I am not sure where it comes from. It
> > says:
> > 
> > ERROR:  Polygon is invalid : interior is not connected 
> > 
> > 
> > 
> > Does that come from boost?
> > 
> > 
> > 
> > So this is 2 questions:
> > 
> > 
> > 
> > 1) Why doesn't ST_Isvalid tell me it is invalid
> > 
> > 2) Where should I search for the different results?
> > 
> > 
> > 
> > As far as I can find I have the exactly same versions on everything
> > on
> > 
> > the installs.
> > 
> > 
> > 
> > 
> > 
> >  POSTGIS="2.5.0dev r16554" [EXTENSION] PGSQL="100" GEOS="3.7.0dev-
> > CAPI-
> > 
> > 1.11.0 r" SFCGAL="1.3.0" PROJ="Rel. 4.9.3, 15 August 2016"
> > GDAL="GDAL
> > 
> > 2.1.2, released 2016/10/24" LIBXML="2.9.4" LIBJSON="0.12.1" RASTER
> > 
> > (1 row)
> > 
> > 
> > 
> > and boost version seems to be the same
> > 
> > Package: libboost-system1.62.0
> > 
> > 
> > 
> > Could someone else with sfcgal enabled see what result they get?
> > 
> > 
> > 
> > select st_tesselate(
> > 
> > 'POLYGON((389923 6365025,390094 6364730,390269 6364430,390261
> > 
> > 6364415,390250 6364399,390239 6364372,390207 6364367,390168
> > 
> > 6364372,390136 6364377,390100 6364393,390081 6364429,390070
> > 
> > 6364458,390059 6364474,390059 6364494,390044 6364497,390019
> > 
> > 6364506,390012 6364512,389985 6364533,389973 6364545,389951
> > 
> > 6364567,389931 6364588,389927 6364598,389912 6364628,389907
> > 
> > 6364636,389883 6364647,389870 6364649,389863 6364638,389858
> > 
> > 6364613,389851 6364591,389817 6364575,389795 6364594,389792
> > 
> > 6364625,389791 6364653,389796 6364679,389802 6364695,389811
> > 
> > 6364722,389840 6364741,389868 6364741,389882 6364721,389900
> > 
> > 6364705,389915 6364699,389915 6364717,389909 6364737,389891
> > 
> > 6364770,389885 6364781,389867 6364798,389845 6364810,389823
> > 
> > 6364809,389801 6364815,389778 6364822,389761 6364822,389742
> > 
> > 6364840,389732 6364863,389741 6364890,389741 6364919,389744
> > 
> > 6364920,389760 6364932,389768 6364940,389774 6364954,389776
> > 
> > 6364963,389787 6364970,389816 6364981,389852 6364993,389895
> > 
> > 6365011,389923 6365025),(390094 6364730,389987 6364914,389981
> > 
> > 6364904,389971 6364887,389947 6364869,389921 6364853,389895
> > 
> > 6364832,389892 6364816,389906 6364812,389941 6364818,389973
> > 
> > 6364827,390021 6364852,390094 6364730),(390094 6364730,390050
> > 
> > 6364714,390050 6364713,390094 6364730),(390050 6364714,390034
> > 
> > 6364736,390014 6364733,389982 6364724,389954 6364721,389953
> > 
> > 6364710,389958 6364695,389964 6364677,389972 6364672,389988
> > 
> > 6364673,390015 6364678,390041 6364695,390049 6364713,390047
> > 
> > 6364713,390050 6364714))'::geometry);
> > 
> > 
> > 
> > 
> > 
> > Thanks
> > 
> > 
> > 
> > Nicklas
> > 
> > 
> > 
> > _______________________________________________
> > 
> > postgis-devel mailing list
> > 
> > postgis-devel at lists.osgeo.org
> > 
> > https://lists.osgeo.org/mailman/listinfo/postgis-devel
> 
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