[OSM-talk] osm2pgsql and proper/legacy mercator

[Andy Allan]

On Fri, May 1, 2009 at 4:52 PM, Francois Van Der Biest
<francois.vanderbiest at camptocamp.com> wrote:
> Hi list,
>
> osm2pgsql --help says:
> -m|--merc: Store data in proper spherical mercator (default)
> -M|--oldmerc: Store data in the legacy OSM mercator format
>
> I'm wondering what's the difference between those two srs.
> Which one is epsg:900913 (aka epsg:3785
> http://www.spatialreference.org/ref/epsg/3785/) ?
>
> My experience (importing an osm dump into postgis, then exporting to
> shapefiles) would let me think that the "legacy OSM mercator format"
> is epsg:3785. So, what's the other one ?

I'm moderately sure that --oldmerc was when someone in OSM got the
maths slightly wrong. Use -m for (as it says) proper spherical
mercator aka epsg:900913

Cheers,
Andy