[OSM-dev] shortest streets

Emilie Laffray emilie.laffray at gmail.com
Thu Sep 17 09:11:33 BST 2009


Stephan Knauss wrote:
> So could you specify a better projection that would be equidistant? The 
> data here uses 900913.
> Would 4326 be equidistant?
>
>   
I wouldn't use 4326 to determine a distance. You may want to use a tool
to calculate an UTM zone for each streets you are measuring to have a
real distance in meters.
> Then it could read like this:
> select osm_id, length(st_transform(way,4326)) as length from 
> planet_osm_roads order by length asc limit 10
>
>   
ST_Length always returns a distance in the unit of the SRID.
> Is there a difference between st_length() and length()? They both return 
> the same values (at least for 900913).
>
>   
They are the same. ST_Length is just the standard name.

Emilie Laffray

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 195 bytes
Desc: OpenPGP digital signature
URL: <http://lists.openstreetmap.org/pipermail/dev/attachments/20090917/2711b4d9/attachment.pgp>


More information about the dev mailing list