[Talk-GB] Postcode centroids

Jerry Clough - OSM sk53_osm at yahoo.co.uk
Fri Jan 21 10:39:59 GMT 2011

A couple of points:

	* Admin. boundaries are not straightforward to verify, but there is plenty of 
suitable objective evidence : from Boundary Markers (e.g., 
http://www.openstreetmap.org/browse/node/502944003), names on rubbish bins, or 
the bin lorries, asset identification numbers on street furniture, asking people 
in the street, out-of-copyright documentary evidence, style and appearance of 
street signs (and other street furniture), sticky labels saying "report a 
problem", etc. Some areas even have local 'beating the bounds' events. ITO 
Analysis also show how useful boundaries are for analytical questions: not every 
interesting boundary will be available in a suitable data-set outwith OSM.
	* Postcode centroids are completely artificial, nothing tangible about them at 
all. The centroids are copyright to Royal Mail, and require an additional 
attribution statement. As may the data derived from them

	* Individually assigned postcodes (whether to a road, an address interpolation 
way or an individual house/flat) provide a much richer FREE dataset than that 
offered by the CodePoint Open set of centroids. The range of use cases for such 
a dataset is much larger, and not restricted to just enabling navigation to 
postcode in satnavs. An obvious application is 'PAFing' address lists: something 
which for charities and small businesses still costs significant sums of money.
	* If you want postcodes in your Garmin it is trivial to build a separate 
transparent layer using mkgmap. There is no need to import them into OSM for 
this purpose.
	* No one is asking you to add postcodes to 25,000 houses: they are just 
providing tools to assist you if that is what you want to do. Generally, adding 
postcodes is trivial compared with the leg work of collecting house numbers, 
adding buildings and verifying streetnames.

From: Kevin Peat <kevin at kevinpeat.com>
To: Tom Hughes <tom at compton.nu>
Cc: Talk-GB <Talk-GB at openstreetmap.org>
Sent: Fri, 21 January, 2011 10:02:50
Subject: Re: [Talk-GB] Postcode centroids

So I should delete the various admin boundaries in the db then as they cannot be 
viewed on the ground?

That's great for Nominatim but what if I want to find a postcode on my Garmin?


On 21 January 2011 09:58, Tom Hughes <tom at compton.nu> wrote:

>Because postcode centroids are not real - they don't exist so fail the
>ground truth rule.
>As I understand things the new version of Nominatim that is coming up
>will search the OpenData postcode data (and various other postcode
>databases for other countries) directly anyway.
>Tom Hughes (tom at compton.nu)

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