thanks for the answers ! The provided links really helped me to see that my own algorithm had a strange behavior...
I am probably going to use the convexHull function ! regards, Nick 2009/2/12 Nico Mandery <[email protected]> > In regards to a convcave hull you might want to check this thread: > > http://www.mail-archive.com/[email protected]/msg05979.html > > nico > > [email protected] schrieb: > > Hallo > > > > you can read about it here: > > http://www.postgis.org/documentation/manual-svn/ST_ConvexHull.html > > ST_ConvexHull will give you a better result but as you see in the > documentation there is no function that gives a concave hull as you have in > your example link. > > > > /Nicklas > > > > > > > > 2009-02-12 My Pid wrote: > > > > Hello, > >> 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 > "208_1_14592_gps"; > >> > >> with gps_coordinates - POINT geometry > >> > >> It seems to output a 4 points polygons and I would like to get something > like > >> > >> > http://realtimeblog.free.fr/cell_map.php?mcc=208&mnc=1&lac=14592&cellid=62403&display=Display > >> > >> > >> > >> Is it possible to use postgis functions to generate this kind of > envelope ? > >> > >> regards, > >> Nick > >> > >> > >> ------------------------------------------------------------------------ > >> > >> _______________________________________________ > >> postgis-users mailing list > >> [email protected] > >> http://postgis.refractions.net/mailman/listinfo/postgis-users > _______________________________________________ > postgis-users mailing list > [email protected] > http://postgis.refractions.net/mailman/listinfo/postgis-users >
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