[postgis-users] Length, distance, area using SRID 6326

[Paul Ramsey]

There is no help to give, you have all the pieces in front of you.   
If your reference system is in spherical coordinates and you do not  
want to do a transform() to a planar system, use the _sphere or  
_spheroid functions.  _sphere is faster than _spheroid, but less  
accurate -- you may find it is well within the tolerances you need  
however.  Spheroid calculations are very expensive, nothing to be  
done about that (difference between a converging set of differential  
equations and a simple trig formula).

P.

On May 20, 2006, at 2:18 PM, Fermín Pieri wrote:

> Hi, I am using SRID 6326 as the spatial reference id of the geom  
> column. But
> when i try to use length, distance and area functions, the results  
> are not
> what i expect (of course, using spherical calcultations) Any idea?  
> Opengis
> specification says that this functions return the result using the  
> SRID of
> the geom column. Why postgis include distance_sphere,  
> length_spheroid, etc.?
> I tried length_spheroid and the result is what i need but it takes  
> a long
> processing time. I will appreciate somebody's help
>
> Thanks
>
> Fermin
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