[Talk-GB] Postcode centroids

Lester Caine lester at lsces.co.uk
Fri Jan 21 12:57:13 GMT 2011


Ed Avis wrote:
> Andy Robinson (blackadder-lists<ajrlists at ...>  writes:
>
>>>> The Open
>>>> data that OS released last year included the Code Point Open dataset
>>>> which has the location of postcode centroids.
>
>>> I think the big question is whether adding them would help Nominatim
>>> resolve postcode searches.  It seems to have some postcode data already but
>>> I don't know where it gets that from?
>>
>> Nominatim works very nicely once you have the postcodes and house numbers in
>> OSM. Just try my postcode B72 1JU in the OSM search box for an example.
>
> I got confused.  The OSM website will do postcode matches using the NPEMap /
> Free The Postcode data when Nominatim doesn't return a result.  These search
> results come up like 'EX13 7##' and must be based on a postcode centroid.
>
> If the centroids were mapped within OSM itself, then Nominatim could do this
> search.  This might be slightly cleaner, but it's more of a technical decision
> than anything else, so it's for Brian Q. and the search form folk to decide.

Many search engines, even map based ones, have used 'EX13 7##' based data until 
quite recently. In the absence of anything better it was all that was available. 
NOW we do at least have the finer detail coordinate data from OS even if it does 
not give real road names. THAT is at least better for looking up 'xx within a 20 
mile radius' where the previous options may well have only had 50 mile accuracy. 
So replacing the course data with finer lookup is at least a step forward.

-- 
Lester Caine - G8HFL
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