[postgis-users] How retrieve number of points based on scale value?

[strk]

On Wed, Mar 10, 2004 at 09:35:45AM +0100, Maurizio Napolitano wrote:
> I want to represent maps on a web GIS, which are composed of multiple
> layers of very large numbers of polygons.
> Given the large number of polygons, the generation of the maps becomes
> computationaly intensive and takes a large amount of time
> to complete.
> So I wanted to know if it were possible to write an SQL query that 
> allows me to retrieve only some of the points of the polygon, based on
> some scale value.
> An example of what I mean is given by the java applet on this site:
> http://www.map24.com/map24/index.php3?map24_sid=d1cc0fc6be8602363b64b65f5f1ae182

I couldn't seen the java map, but I suspect this is something 
I've already handled to do. I made a stored procedure which
transformed a postgis geometry making each of its points fall
on a grid defined by its origin and cell size. Adiacent points
falling an the same cell are merged togheter thus making the
geometry smaller (in points and size) as you enlarge the 'grid'.
It's like mapsever's raster-based reduction.

Is this what you're looking for ?

> -- 
> Maurizio Napolitano <napo at itc.it>
> ITC-irst

--strk;