[postgis-users] st_within operation not considering sphericaldistortion

[info at georgherdt.de]

Hi Ralf,
thanks for your quick response. I've been looking at 3035 (ETRS89).  
The problem for me with this spatial reference system is, that my  
geometries are spanning over the whole world.
Maybe you know a srs which covers -180 to 180 and -90 up to 90 ???


Cheers

Georg



Zitat von "Suhr, Ralf" <Ralf.Suhr at itc-halle.de>:

> Yes it's only thinking,
>
> select st_within(ST_Transform(st_geomfromtext('POINT (-40  
> 44.1)',4326),3035),ST_Transform(st_geomfromtext('POLYGON((0 44, -90  
> 44, -90 46, 0 46, 0
> 44))',4326),3035));
>
>  st_within
> -----------
>  F
>
> If you use only EPSG:4326 all coordinates are plain orthogonal and  
> your query is true.
>
> Gr Ralf
>
> -----Ursprüngliche Nachricht-----
> Von: postgis-users-bounces at postgis.refractions.net  
> [mailto:postgis-users-bounces at postgis.refractions.net] Im Auftrag  
> von info at georgherdt.de
> Gesendet: Montag, 8. März 2010 15:49
> An: postgis-users at postgis.refractions.net
> Betreff: [postgis-users] st_within operation not considering  
> sphericaldistortion
>
> Hi,
>
> yet I'm quite new to the list, I'm using postigis for some time.
> For now I discovered the following behaviour for this query:
>
> select st_within(st_geomfromtext('POINT (-40
> 44.1)',4326),st_geomfromtext('POLYGON((0 44, -90 44, -90 46, 0 46, 0
> 44))',4326))
>
> Stating that the point (-40,44.1) is within the given polygon. But
> when considering the spherical "distortion" (the connect between the
> points are arcs not straight lines) on the described polygon this
> point cannot be within.
> I've seen that there are some functions for calculating spherical
> distances but, nothing similar for the st_within function.
>
> Can anybody help me whats wrong with that. Maybe its my thinking ;-)
>
>
> Best regards
>
> Georg Herdt
>
>
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