[postgis-users] Polygon validity

[Rykov Denis]

Thanks a lot for taking you time to explain.

So if  Postgis actually not limit only to the simple-feature model the
ST_IsValid,
what kinds of geometries are InValid in PostGIS terms?

So does this make my example non-compliant with OGC SFA? I'm not
topology expert and asking for the practical reasons, the software
that claims to be OGC-compliant cannot import such data correctly. If
such structures are indeed not covered by OGC SFA then I cannot do
anything, if they are allowed, than this is a software issue and it is
in fact not compliant.

2010/3/31 Andrea Peri <aperi2007 at gmail.com>:
>>with two duplicate nodes. When I try to check it with ST_IsValidReason
>>function I get message
>>that it is Valid Geometry. Is this OGC compliant? When I try to check
>>it with QGIS, ArcView or
>
>>ArcGIS - I get notice about self intersection. Please explain this
>> situation.
>
> Hi,
>
> give my explain...
>
> The selfintersect is an invalidity for OGC because OGC use the
> simple-feature model.
>
> Postgis actually not limit only to the simple-feature model the ST_IsValid.
> (even if other postgis functions are simple-feature only)
>
> Another think to understand is that the OCG-simple-feature model actually is
> only 2D and don't know the 3D dimension.
>
> So is quite difficult limit the ST_IsValid only to the simple-fature model.
>
> --
> -----------------
> Andrea Peri
> . . . . . . . . .
> qwerty àèìòù
> -----------------
>
>
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