[postgis-users] Postgis Simplify

[strk at refractions.net]

Christo, nothing weird about it, not every shape contains redundand
informations.

Consider a straight line defined by millions of intermediate points.
A simplify(geom, 0) would make it a 2 point line.

If you google for Douglas-Peuker you'll get
lots of informations about the algorithm.

--strk;

On Mon, Jul 25, 2005 at 10:20:23PM +0200, Christo Du Preez wrote:
> This is really weird.
> 
> select npoints(the_geom), npoints(Simplify(the_geom, .1))
> from province
> 
> results to:
> 
> 1:	25290,		39
> 2:	23978,		43
> 3:	25999,		22046
> 4:	4996,		19
> 5:	24679,		31
> 6:	50819,		43120
> 7:	31899,		71
> 8:	63292,		45
> 9:	84990,		70460
> 10:	12878,		15
> 11:	1047,		8
> 
> The data is lat/long wgs84, what could cause rows 3,6 and 9 not to 
> simplify as much as the others?
> 
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