[postgis-users] boundary or envelope of cloud of points

My Pid mamat750 at gmail.com
Thu Feb 12 02:12:44 PST 2009


I am really a newbie in the postgis world.

I am a developper for http://www.openbmap.org/ website
which identify GSM cell area from measures of GSM data
and GPS coordinates.

So I am planning to go from mysql to postgresql/postgis
and I am looking for a function that does the following:

I have a table containing the gps coordinates mentionned above.
I would like to generate a enveloppe or a boundary of the area
of the GSM cell.

What I have tried (among others)

SELECT ST_AsText(ST_Envelope(ST_Collect(gps_coordinates))) FROM

with gps_coordinates - POINT geometry

It seems to output a 4 points polygons and I would like to get something


Is it possible to use postgis functions to generate this kind of envelope ?

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