[OSM-talk] Google Maps comparison

[Dair Grant]

Hi,

I recently finished mapping the town I live in, and thought it 
would be interesting to do a detailed comparison with Google 
Maps (or really, the TeleAtlas data it is based on).

Once the OSM version was finished, I reviewed each street to 
check it against the equivalent in GM. You can see the results at:

     <http://www.refnum.com/osm/gmaps.html>

Although the missing road figures are inflated by a "new" (2004) 
housing estate, the overall error rate is surprisingly high.


This should also be confirmation (if anyone was in any doubt) 
that entering data into OSM by tracing a commercial source is a 
really really bad idea.

Many of these errors will probably go uncorrected for years, and 
it would be extremely easy to insert deliberate errors without 
affecting the usability of the map.

It would also be trivial to re-survey an area to detect these 
kind of errors, then use that list of corrections to check for 
identical mistakes in a suspect map.


-dair
___________________________________________________
dair at refnum.com    http://www.deathvalleycycle.com/