[postgis-users] Polygon validity

[Andrea Peri]

>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.

-- 
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Andrea Peri
. . . . . . . . .
qwerty àèìòù
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