[geos-devel] MULTI* and Invalid
strk at keybit.net
Fri Jun 14 06:41:26 PDT 2013
On Fri, Jun 14, 2013 at 01:16:02PM +0200, Oliver Courtin wrote:
> Below an example, throught PostGIS
> with GEOS 3.3.5-CAPI-1.7.5:
> SELECT ST_IsValidReason(
> 'MULTIPOLYGON(((0 0,1 0,1 1,0 1,0 0)),((1 0,2 0,2 1,1 1,1 0)))'::geometry
> Output: Self-intersection[1 0]
> After looking in SFS and ISO 19107,
> we didn't find at first sight
> why such a geometry should be invalid.
> Could you give us some light on it ?
The two components have a lineal intersection.
Puntal intersection would be considered valid
(ie: moving vertex 1,1 to 1,1.5).
IIRC there was a "single point" wording in the spec, but
Martin will know more about this.
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