[postgis-users] generate a geometry column of random point, line and polygon

[Shaozhong SHI]

The simplicity is beautiful.  Any simple script to do so?  I think that
will be an useful addition.
Regards,
David

On Friday, 8 September 2023, Regina Obe <lr at pcorp.us> wrote:

> David,
>
>
>
> For this are you needing to generate random points from a line or polygon
> or are you trying to generate random polygons, lines, and points?
>
>
>
> If you need to generate random points from a polygon:
>
>
>
> Use ST_GeneratePoints:  https://postgis.net/docs/en/ST_GeneratePoints.html
>
> Note there is a option seed argument, that will give you the same exact
> answer if you give it the same seed, but without that the generated points
> will be different each time.
>
>
>
> As I recall, ST_GeneratePoints only works with areals so won’t work with a
> line, however you can buffer a line very thinly to do the same. Use a flat
> buffer:
>
>
>
> https://postgis.net/docs/en/ST_Buffer.html
>
>
>
> SELECT ST_GeneratePoints(ST_Buffer(
>
> ST_GeomFromText(
>
>   'LINESTRING(50 50,150 150,150 50)'
>
> ), 0.5, 'endcap=square join=round'), 1000);
>
>
>
>
>
> If you want to generate random polygons, you could use ST_ConcaveHull or
> ST_AlphaShape around the section of a polygon you did a ST_GeneratePoints on
>
>
>
> And then use something like https://postgis.net/docs/en/ST_Subdivide.html
> to chop up the polygons.
>
>
>
> To get a linestring out of that (It will be closed), you can take the
> boundary of any of the above
>
>
>
> https://postgis.net/docs/ST_Boundary.html
>
>
>
> Hope that helps,
>
> Regina
>
>
>
> *From:* postgis-users <postgis-users-bounces at lists.osgeo.org> *On Behalf
> Of *Shaozhong SHI
> *Sent:* Friday, September 8, 2023 7:56 AM
> *To:* PostGIS Users Discussion <postgis-users at lists.osgeo.org>
> *Subject:* [postgis-users] generate a geometry column of random point,
> line and polygon
>
>
>
> Is a simple way to do this?
>
>
>
> Regards,
>
>
>
> David
>
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