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List: postgis-users
Subject: Re: [postgis-users] How to generalize or simplify a Polygon
From: strk <strk () freek ! keybit ! net>
Date: 2003-08-29 20:17:17
Message-ID: 20030829221717.A55242 () freek ! keybit ! net
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The extension works for both lines and polygons.
Does not try to solve the self-intersection problem.
Simplified features can be stored back to db.
--strk;
spoerri wrote:
> I'm not sure if this was mentioned before, but earlier this summer their was a
> post on the list by somebody that implemented the D-P algorithm on lines as
> an extension/function to PostGIS. This may be a good starting point to also
> simplify polygons (if required).
>
> Along this line, I was also think if it would be possible/useful to store the
> simplified feature within the database. This would then allow the user to
> specify which 'version' of a spatial dataset should be retrieved. This would
> provide a similar functionality as is already available for raster datasets
> where pyramids are used to provide this functionality. What does the rest of
> you think about this?
>
> Christoph
>
>
> On Thursday 28 August 2003 04:29 pm, Martin Davis wrote:
> > > of self-intersection when you process a polygon. So why not put it in as
> > > an method that is only a member of LineString / MultiLineString class ?
> >
> > If we were putting D-P into JTS, that would be one place to put it,
> > alright. However, as I said I'd really rather keep JTS focussed on core
> > algorithms.
> >
> > On a philosophical note, adding algorithms as methods to Geometry objects
> > seems to be encouraged by the OO paradigm, but it's not the most scalable
> > or flexible way of doing things. For algorithms such as D-P which are
> > pretty independent of the internal representation of the Geometry I think
> > it's nicer to keep them outside the Geometry class in a separate algorithm
> > class.
> >
> > Martin Davis, Senior Technical Architect
> > Vivid Solutions Inc.
> > Suite #1A-2328 Government Street Victoria, B.C. V8T 5G5
> > Phone: (250) 385 6040 Fax: (250) 385 6046
> > EMail: mbdavis@vividsolutions.com Web: www.vividsolutions.com
> >
>
>
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