[postgis-users] How to generalize or simplify a Polygon
strk at freek.keybit.net
Tue Sep 2 09:36:30 PDT 2003
Sorry, but the distribution server seems to be down:
http://cobalt.rmnet.it/~san/postgis/ (in case of a quick restore)
If anyone wants to give postgis D-P a try tell me and I'll send you a copy
(untill the server will be back up)
> 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.
> 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 at vividsolutions.com Web: www.vividsolutions.com
> > >
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