[postgis-users] Combines polygons within a specified distance to each other into new polygons.

[Paragon Corporation]

Peter,
You would use a combination of ST_DWithin, ST_Collect, and ST_ConvexHull.
When you say within a max distance -- you mean of a reference geometry or
from each other?  From each other can be kind of expensive.

So something of the form

SELECT ST_ConvexHull(ST_Collect(the_geom))
FROM table_of_polygons
WHERE ST_DWithin(ST_GeomFromText(.....), the_geom, max_dist)

http://postgis.refractions.net/documentation/manual-svn/ST_ConvexHull.html

http://postgis.refractions.net/documentation/manual-svn/ST_Collect.html

http://postgis.refractions.net/documentation/manual-svn/ST_GeomFromText.html

http://postgis.refractions.net/documentation/manual-svn/ST_DWithin.html

Leo



-----Original Message-----
From: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of Peter
Freimuth
Sent: Saturday, September 05, 2009 9:26 AM
To: PostGIS Users Discussion
Subject: [postgis-users] Combines polygons within a specified distance to
each other into new polygons.

Hi PostGIS User,
i am searching for a postgis based solution to create a convexhull on groups
of polygons which are grouped via a max distance value.



Any idea or a solution is welcome!

Kind regards,
Peter



-- 
Peter Freimuth  Muskauer Str. 11   10997 Berlin
Location:http://www.berlinonline.de/citymap/map.asp?start.x=5&plz=10997&str=
Muskauer+Str.+11&grid=dedatlas10
============================================================================
============================
Tel:+49(0)30-69816610  Mobil:+49(0)175-8434074  Firma:+49(0)3381-8904327
============================================================================
============================
mailto:pfreimuth at arcor.de
skype:pfreimuth
msn:peter_freimuth at hotmail.com

_______________________________________________
postgis-users mailing list
postgis-users at postgis.refractions.net
http://postgis.refractions.net/mailman/listinfo/postgis-users