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

[Stephen Woodbridge]

Paul Ramsey wrote:
> Interesting jumping off point for a discussion of new technology ideas...
> 
> - heatmap in the database

you mean we finally have a use case for raster in the DB ;)
but seriously this would be able interesting add on.

> - contouring in the database

As would this. If you coupled this with the Dijkstra cost at a node as 
the z-value, contouring gives you isocrons of the Dijkstra solution.

> - kriging in the database (I know, already there w/ R)

Would like to see more work done on the topology code :) Especially with 
an eye toward shared boundaries and manipulating them.

-Steve W

> P
> 
> 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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