[postgis-users] Postgis Simplify

[Christo Du Preez]

I used another installation, this time Linux and did the same test.

This time the result was different on rows 3, 6 and 9. More what I was 
expecting in the first place.

1:   25290 :  39
2:   23978 :  43
3:   25999 :  41
4:   4996  :  19
5:   24679  : 31
6:   50819 :  25
7:   31899 :  71
8:   63292 :  45
9:   84990 :  59
10: 12878 :  15
11: 1047   :   8

In previous posts I also mentioned the exponential format that my result 
was, doing a Simplify(). I have also noticed that the exponential format 
was only on rows 3, 6 and 9. The rest of the results was lat/long wgs84, 
as expected.

Can someone please shed some light on this?


strk at refractions.net wrote:

>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?
>>
>>_______________________________________________
>>postgis-users mailing list
>>postgis-users at postgis.refractions.net
>>http://postgis.refractions.net/mailman/listinfo/postgis-users
>>    
>>
>_______________________________________________
>postgis-users mailing list
>postgis-users at postgis.refractions.net
>http://postgis.refractions.net/mailman/listinfo/postgis-users
>
>
>  
>

-- 
Kind Regards,
Christo Du Preez

Senior Software Engineer
Mecola IT
http://www.mecola.com
+27 [0]82 4255 895