[postgis-users] POLYGON from LINESTRING

[Bernhard Reiter]

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On Wed, Apr 24, 2002 at 03:46:04PM -0700, Paul Ramsey wrote:
> No there is not a simple way. Type casting is not specified in SFSQL.=20

Could have been a PostGIS addition or a commonly asked question,=20
couldn't it? :)

> I guess it behooves me to ask why you are loading your polygons as
> linestrings?

Well a matter of the source quality.
It is a layer coming over by shape format,=20
which mostly contains linestrings.
Some of them are areas, though.

Of course SQL queries and the PostGIS function can be used to
identify the linestrings that should be polygons.

> (The non simple way is to extract them, re-write their types as POLYGON
> and re-insert them.)

Thought of that, but wanted to be sure.
Thanks.

> Bernhard Reiter wrote:
> >=20
> > Is there a simple way to create a POLYGON from
> > a LINESTRING which tests positive to IsClosed()?
> >=20
> > Same for MULTIPOLYGON from MULTILINESTRING?
> >=20
> > I haven't found a obvious and simple method.
> > What am I missing?

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