On Sat, Aug 02, 2014 at 11:52:58AM +0100, Éric Gillet wrote:
> > On Sat, Aug 2, 2014 at 9:52 AM, Christian Quest <[email protected]>
> > wrote:
> >> By default osm2pgsql reprojects into web mercator, but you can avoid it
> >> and ask to keep the spherical coordinates if this is a better choice for
> >> your use.
> May I ask how to use spherical coordinates ? I've hit the problem about
> distances being distorded with projections, and never managed to do it
> right with osm2pgsql based db.
Distance between Berlin and London:
select ST_Distance(Geography(ST_GeometryFromText('POINT(13.3888598981363
52.517036494754)')), Geography(ST_GeometryFromText('POINT(-0.127647399982231
51.5073218947764)')))
-> 933410.764104169 m
If you have the coordinates in spherical mercator, you need to reproject
them to WGS-84, using:
select name, way from planet_osm_point where osm_id='240109189'; -- Berlin
-> Berlin | 010100002031BF0D001C0FF01009BE3641B969376A934C5A41
select name, ST_astext(way) from planet_osm_point where osm_id='240109189';
-> Berlin | POINT(1490441.06616301 6894157.65963214)
select name, ST_astext(ST_Transform(way, 4326)) from planet_osm_point where
osm_id='240109189';
-> Berlin | POINT(13.3888598981363 52.517036494754)
select name, ST_astext(Geography(ST_Transform(way, 4326))) from
planet_osm_point where osm_id='240109189';
-> Berlin | POINT(13.3888598981363 52.517036494754)
(same as before, but can be used to make projected calculations)
greetings,
Stephan
--
Seid unbequem, seid Sand, nicht Öl im Getriebe der Welt! - Günther Eich
,---------------------------------------------------------------------.
| Stephan Bösch-Plepelits, |
| Technische Universität Wien - Studien Informatik & Raumplanung |
| Projects: |
| > openstreetbrowser.org > couchsurfing.org > tubasis.at > bl.mud.at |
| Contact: |
| > Mail: [email protected] > Blog: plepe.at |
| > Twitter: twitter.com/plepe > Jabber: [email protected] |
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