Hi Dave, I would have thought ST_Simplify() would met your requirements.
If you use it with a buffer distance of zero, then the full resolution is retained, but any points on a straight boundary segment which are redundant are removed. This is the minimum number of vertices required to define the polygon in full resolution. You can progressively remove vertices which make least changes to the polygon definition by increasing the buffer distance, but where boundaries are shared between neighbouring polygons this can cause mis-alignments. Cheers, Brent Wood --- On Sat, 4/7/12, Dave Potts <dave.po...@pinan.co.uk> wrote: From: Dave Potts <dave.po...@pinan.co.uk> Subject: [postgis-users] simplifying a polygon To: postgis-users@postgis.refractions.net Date: Saturday, April 7, 2012, 9:52 AM I have polygon made up of many different points,it some cases its rather to accurate for my requirments,i.e. its generating a lot points to describe a minor change. I had throught that by saying something like select ((st_dumppoints( (st_intersection(ST_Segmentize(st_exteriorRing(jt.the_Geom),70000),pa.the_geom)) )).geom) as the_geom from journey_table jt, coast_polygon pa where jt.generation=1 Would give me minmum list of data points for describing a polygon. What it does give me long gap, 3 coordinates, another long grap then another 3 coorindates etc Where these 3 coordinates are they close together. What I had hope to get list the lowest number points that would be useful to describe a polygon. Q. Is there a better way of doing this. Dave. _______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
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