Hi Rene, Perhaps something like this?
select region, ST_simplify(ST_buffer(ST_convexhull(ST_collect(geom), n),n/3)) from table group by region; ST_simplify removes extraneous vertices - increase the n/3 parameter to remove more vertices, but you'll also need to increase n to ensure all the points lie within the simplified polygon - you don't have to use n/3, just a value off the top of my head ST_buffer will create a new polygon distance n outside the original one ST_convexhull will create a polygon encompassing the points. ST_concavehull might also work, but I've found it problematic. ST_collect will create a group of points to work with all grouped by region. HTH, Brent Wood --- On Tue, 9/11/12, René Fournier <m...@renefournier.com> wrote: From: René Fournier <m...@renefournier.com> Subject: [postgis-users] Creating a simple polygon encompassing a given number of points To: "PostGIS Users Discussion" <postgis-users@postgis.refractions.net> Date: Tuesday, September 11, 2012, 6:39 AM I've written a script to migrate location data from MySQL to PostGIS. Each region contains 5-20 locations. I would like my script to create a simple polygon for each region that encompasses its locations (lat/lng points). I say simple in the sense of not too many vertices (< 10), even if the region contains 20 points.(The easiest thing would be a bounding box, but I would like it a bit more defined than that.) Additionally, I would like the polygon to be a bit bigger (say, by 10 meters) than the points it contains. Just wondering if this is something that can be done in a PostGIS query or PHP using some algorithm for simple. What would you recommend? Thanks! ...Rene _______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
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