[postgis-users] How to get the distance between geometry inmeters?

[R H]

That works great.  Thanks for all the help.
> Date: Thu, 20 Mar 2008 13:25:35 -0700> From: kneufeld at refractions.net> To: postgis-users at postgis.refractions.net> Subject: Re: [postgis-users] How to get the distance between geometry inmeters?> > Ah. So your first attempt is incorrect. When you first create your > geometries, you need to set the srid of your new geometries to the > projection they are currently in. Since your input is lat/long, you need > to set the srid of your new geometries to the lat/long projection. > *Then* you can transform your geometries into 26912 and query for things > like distance.> > Try this:> select AddGeometryColumn('table','geocode', 26912, 'POINT', 2);> update table> set geocode = transform(PointFromText('POINT(' || longitude || ' ' || > latitude || ')', 4269), 26912);> > -- or better, since going through the text representation introduces > coordinate drifting.> select AddGeometryColumn('table','geocode', 26912, 'POINT', 2);> update table> set geocode = transform(setsrid(MakePoint(longitude, latitude), 4269), > 26912);> > then distance(geocode, geocode) will return meters.> > I hope this clarifies things.> Cheers,> Kevin> > R H wrote:> > My explanation wasn't that great. Below is what I did.> > > > 26912 projection is in meters (right?)> > select AddGeometryColumn('table','geocode', 26912, 'POINT', 2);> > update table> > set geocode = PointFromText('POINT(' || longitude || ' ' || latitude > > || ')', 26912);> > distance(geocode, geocode) returns degrees> > > > ALTER TABLE property DROP COLUMN geocode> > > > 4269 projection in degrees> > select AddGeometryColumn('table','geocode', 4269, 'POINT', 2);> > update table> > set geocode = PointFromText('POINT(' || longitude || ' ' || latitude > > || ')', 4269);> > distance(transform(geocode, 26912), transform(geocode,26912)) returns > > meters> >> > > > I would prefer not to do the transform() if don't have to speed and > > accuracy reasons. Thanks for help. : }> > > _______________________________________________> postgis-users mailing list> postgis-users at postgis.refractions.net> http://postgis.refractions.net/mailman/listinfo/postgis-users
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