[postgis-users] creating a mask

[Fred Lehodey]

Hi Erik,
you can try something like that:  (?)
select  st_difference(ST_envelope(the_geom),the_geom)  from mytable

Fred



On Thu, Aug 7, 2008 at 2:11 PM, erik <whatevar89 at gmail.com> wrote:

> Hello,
>
> I don't know if the terminology I use is correct but I would like to create
> a mask of layer I have.
> For example, from the shape of the world I would like to keep only the
> oceans, the negative of the initial shape.
> I haven't found any info or documentation about this. Can this be done in
> PostGIS?
>
> Many thanks!
>
> Erik
>
> _______________________________________________
> postgis-users mailing list
> postgis-users at postgis.refractions.net
> http://postgis.refractions.net/mailman/listinfo/postgis-users
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/postgis-users/attachments/20080807/5ab2337c/attachment.html>