[postgis-users] Getting boundary of set of polygons

[Nicolas Ribot]

Hi,

You should try st_makePolygon, or st_buildArea depending on the result you
want (keeping holes or removing them).

Nicolas



On 27 January 2014 13:32, Tom McCallum <termcc at googlemail.com> wrote:

> Hello all,
>
> I am trying to get the boundary of a geometry(polygon) field in postgis
> (multiple polygons in this field).  I have this so far:
>
> ST_BOUNDARY(ST_COLLECT(wkb_geometry))
>
> which outputs MultilineString.  I need to convert this to a polygon.  I
> have tried all sorts of things from ST_DUMP to converting to text and then
> trying ST_BdPolyFromText but got nothing to work so far.  ST_Convexhull
> gives me a polygon but unfortunately its not what I want.
>
> Could someone let me know what I should be calling.
>
> Thanks
>
> Tom
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