[postgis-tickets] [PostGIS] #3083: Add ST_MinimumDiameter() from GEOS

[PostGIS]

#3083: Add ST_MinimumDiameter() from GEOS
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 Reporter:  sfkeller     |       Owner:  pramsey
     Type:  enhancement  |      Status:  new    
 Priority:  low          |   Milestone:         
Component:  postgis      |     Version:  2.1.x  
 Keywords:               |  
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Comment(by robe):

 Bruce and I asked this about 6 years ago before Bruce created
 ST_MinimumBoundingCircle as he thought it would be useful for building
 ST_MinimumBoundingCircle.

 Martin responded.  Here is the thread:

 http://lists.osgeo.org/pipermail/geos-devel/2009-January/003861.html
 and key elements of it:


 ----
 > Bruce Rindahl wrote:
 > > I just looked at MinimumDiameter.cpp and the code does the same thing
 > > as the first part of my code linked by Regina.  This would be nice to
 > > have except for one thing - it may not work.  It calls
 > > distancePerpendicular which I couldn't find.  If this finds the point
 > > furthest from the /extended/ line segment and uses this to compute the
 > > diameter it is the same method as I used - rotate the geometry so the
 > > segment is horizontal and compute the bounding box.  I can provide you
 > > with a geometry where this algorithm fails.  Lee Meilleur can also
 > > provide a counter example.  Because of this I changed my code to test
 > > every point pair for the Minimum Diameter.
 > > Bruce Rindahl
 > >
 > > Martin Davis wrote:
 > >> Yes, this is computing the same thing as the Minimum Bounding Circle
 > >> algorithm.  This algorithm appeared in JTS for some reason which is
 > >> lost in the mists of time.  AFAIK it's never really been used or
 > >> tested extensively.
 > >> It probably postdated the initial port of GEOS, and I guess nobody
 > >> went looking for it until now...
 > >>
 > >> Obe, Regina wrote:
 > >>>
 > >>> I was snooping around the GEOS library and noticed a curious
 > >>> algorithm class
 > >>> called MinimumDiameter.  As far as I can tell from scanning the
 code,
 > >>> it seems similar in concept to the the Minimum Bounding Circle
 > >>> plpgsql algorithm that
 > >>> Bruce posted in November
 > >>>

 ----


 Anyway there is a reason we didn't expose it, not sure if that reason is
 still relevant:



 strk you know if this function is still broken?

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Ticket URL: <http://trac.osgeo.org/postgis/ticket/3083#comment:1>
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