[postgis-users] distance between multiple polygons

[Martin Davis]

Finding the maximum distance between two polygons from a set is going to 
be very slow.  Also, there's no built-in function to do this, so you'd 
have to code it up yourself.

It would be faster to find the bounding box of all the geometries and 
use that to determine a visibility area.



Kevin Kempfer wrote:
> Hello!
>
> I have to find out which polygons have the longest distance between any
> two polygons (or points of them) from a set of multiple polygons. For
> example:
>
> I have 5 polygons.
> Find out where's the biggest distance between them and give back the two
>   points.
>
> I need this to be able to zoom in/out my map application to a zoom level
> where all polygons are visible to the user.
>
> Is this possible using build-in postgis functions or do I have to write
> my own?
>
> Best regards,
>
> Kevin
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-- 
Martin Davis
Senior Technical Architect
Refractions Research, Inc.
(250) 383-3022