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

Emilie Laffray emilie.laffray at gmail.com
Wed Sep 30 14:19:23 BST 2009


2009/9/30 Andy Robinson (blackadder-lists) <ajrlists at googlemail.com>

>
> 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?
>

If you want to obtain length in meters, you need a database that supports
geodesic models. Postgis only supports with ST_Distance_Sphere or
ST_Distance_Spheroid and only between two points.
Geodesic support is quite difficult to get. Then again, you can probably use
an UTM projection in part of the world to get a distance in that part of the
world that would more or less accurate.

Emilie Laffray
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