[postgis-users] unit

David Bitner osgis.lists at gmail.com
Tue Jan 24 06:42:04 PST 2006

Yes, for geographic coordinates (latitude/longitude)
distance(geometry) does not really mean anything useful at all.  Think
about what one degree along the equator vs. one degree near the poles.
 Using cartesian math, each distance is the same when in reality they
are very different.  For angular coordinates, you need to use the
angular measurements distance_spheroid and distance_sphere.

On 1/24/06, Markus Schaber <schabi at logix-tt.com> wrote:
> Hi, Gilbert,
> Gilbert, Antoine wrote:
> > When you are using functions like Distance(geometry, geometry), withinh
> > SQL queries, does it exists an easy way to tell the system I want
> > kilometer units ?
> If your coordinates are in lat/long, than have a look at
> distance_spheroid and distance_sphere, they give the distance in meters.
> Markus
> --
> Markus Schaber | Logical Tracking&Tracing International AG
> Dipl. Inf.     | Software Development GIS
> Fight against software patents in EU! www.ffii.org www.nosoftwarepatents.org
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