[OSM-dev] Default scale / meters per unit ?

Andy Robinson (blackadder-lists) ajrlists at googlemail.com
Wed Sep 30 13:30:52 BST 2009


Tom Hughes wrote:
>Sent: 30 September 2009 12:55 PM
>To: Jonas Donovan Hansen
>Cc: dev at openstreetmap.org
>Subject: Re: [OSM-dev] Default scale / meters per unit ?
>
>On 30/09/09 12:14, Jonas Donovan Hansen wrote:
>
>> When importing openstreetmap with osm2pgsql and default settings
>> (900913) - how many meters is a unit?
>
>The units are meters, but meters on the projected map not great circle
>meters on the surface of the earth.
>
>What osm2pgsql does when you import in that mode is to project the data
>onto a giant flat sheet - effectively it unrolls the globe and stretches
>it until it is flat. The resulting coordinates are in meters but meters
>on that imaginary projected surface.

Does this mean that when you have in the past pulled way length totals from
the pgsql db that the values will not be true to life?

Cheers

Andy 






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