Thanks Martin - Ill have a look at JTS - otherwise I think I will be implemeting it based on the steps Brent mentions.
I believe ArcGIS 10 has a set of tool to create them as well - but requires an info license. Thanks everyone for the help :) Madison On 19 June 2012 04:39, Martin Davis <mtncl...@telus.net> wrote: > JTS has a class for computing a Minimum Bounding Rectangle: > > http://tsusiatsoftware.net/jts/javadoc/com/vividsolutions/jts/algorithm/MinimumDiameter.html > > This may be in GEOS as well. > > > On 6/18/2012 9:36 AM, Brent Fraser wrote: >> >> Madison, >> >> I went looking a few months ago, but could find nothing. I wrote some >> PHP to: >> 1. Find the length of the polygon (vertices farthest apart) >> 2. Find the width (based on vertices farthest from length line) >> 3. Build bounding box using length (with angle of the the length line) >> and the width >> >> I'm still pondering the result when the input polygon is a square... >> >> But there should really be something like a "ST_ExtentRotated" or >> "ST_RotatedBBox" function in PostGIS. >> >> Best Regards, >> Brent Fraser >> >> On 6/15/2012 2:03 PM, Madison Shaw wrote: >>> >>> Hi, >>> >>> I was wondering if any one could possibly offer some advice. >>> >>> I am wanting to calculate the area for a minimum bounding rectangle >>> for individual polygon features. I know I can use st_envelope or >>> st_extent along with st_area but this doesn't quite give me the >>> results I am after. >>> >>> For example if the polygon was already a rectangle but was orientated >>> on an angle the bounding box area is much larger than the area of the >>> original rectangle, whereas I would like it to be the same value. I >>> suppose what I am after is a convex hull but as a rectangle. Is this >>> possible? >>> >>> Any help is greatly appreciated. >>> >>> Cheers >>> >>> Madison >>> _______________________________________________ >>> postgis-users mailing list >>> postgis-users@postgis.refractions.net >>> http://postgis.refractions.net/mailman/listinfo/postgis-users >>> >> >> >> >> _______________________________________________ >> postgis-users mailing list >> postgis-users@postgis.refractions.net >> http://postgis.refractions.net/mailman/listinfo/postgis-users >> >> >> ----- >> No virus found in this message. >> Checked by AVG - www.avg.com >> Version: 2012.0.2179 / Virus Database: 2433/5077 - Release Date: 06/18/12 >> >> > _______________________________________________ > postgis-users mailing list > postgis-users@postgis.refractions.net > http://postgis.refractions.net/mailman/listinfo/postgis-users _______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
