[postgis-users] "Summarizing" a collection of geometries

[Dylan Beaudette]

On Monday 21 April 2008, Paul Ramsey wrote:
> Interesting jumping off point for a discussion of new technology ideas...
>
> - heatmap in the database
> - contouring in the database
> - kriging in the database (I know, already there w/ R)
>
> P

Aren't these inherently cell-based (i.e. grid/raster) operations? Not that it 
wouldn't be nice to implement these things...

Dylan

> On Mon, Apr 21, 2008 at 3:55 PM, Reid Priedhorsky <reid at umn.edu> wrote:
> > Dear list,
> >
> >  I would like to compute a "summary" of a collection of geometries
> > (points, linestrings, polygons, or any combination).
> >
> >  Here is the use case. I would like to summarize the geometry collection
> > and present this summary visually so users working at a small scale can
> > see, "ah, if I zoom in here, I can see more details about this geometry
> > collection".
> >
> >  The simple solution would be to compute a convex hull or bounding box,
> > but this fails if the members of the collection are far apart (users
> > could zoom into the middle and see nothing). In this case the summary
> > would need to be a multipolygon. But the trick is figuring out when to
> > split summary polygons into multipolygons.
> >
> >  Has this been done? Do any of you have suggestions or references?
> >
> >  It is very preferable to do this entirely in the database rather than in
> > external code. Embedded procedures are fine.
> >
> >  As you can see I am not entirely sure of my terminology, so any
> > suggestions there would be welcome as well.
> >
> >  Many thanks,
> >
> >  Reid
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>
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-- 
Dylan Beaudette
Soil Resource Laboratory
http://casoilresource.lawr.ucdavis.edu/
University of California at Davis
530.754.7341