[Wikimedia-l] TomTom does a Britannica

[Tom Morris]

On 29 May 2012 13:38, Richard Symonds <richard.symonds at wikimedia.org.uk> wrote:
> Tom: Is there a way to find out where OSM isn't very accurate/complete?
>

Well, there's OSM "bugs". Basically, there is a way you can file a bug
on the map, sort of like how you might leave a note on a talk page
(only there is some actual bug semantics) or whack a big warning
template on the top of an article. If you are editing in Potlatch,
it'll show the bugs as little red ladybugs! ;-)

Of course, the only way to really know is to compare OpenStreetMap to
reality or to another map or to a data source. Comparing to reality is
time-consuming, and is basically what OSMers do every time they go out
and trace new paths. Comparing to another map is hard because of
copyright issues and getting the data from that map in a usable form.
Comparing to a data source is a very limited way of measuring
completeness. One way that would be fairly good for the United
Kingdom, for instance, would be to get hold of some dataset from the
government of every institution of a similar type (hospitals and
doctor's surgery information is available from the NHS, for instance,
and I believe school data might be available also) and then write a
script to see if there is something with a very similar name in the
vicinity on OSM.

Personally, I find that whenever I look something up about somewhere I
know, work or live, OSM is pretty good. There are issues: occasionally
I'll find a street name that's wrong. But when using Google Maps, I
find all sorts of inaccuracies, mostly derived from SEOers spamming
Google Maps. I saw an SEO consultant who managed to get their business
listing bang in the centre of the Houses of Parliament once.

-- 
Tom Morris
<http://tommorris.org/>