[Openstreetmap] Re: [Geowanking] freeing the postcode database

[Saul Albert]

Hi Steve,

Admirable, nice url :)

This has been a sticking point for ages.. Some initial pointers from
various conversations on the issue:

- Is it the postcode/geocode pair that's crown copyright, or the use of
  the codes themselves? Is there any advice on this that you've had that
  indicates that this approach would actually work legally?

- There are 1.6 million postcodes containing about 24 million addresses.
  That's a lot. Might it be possible to reverse-engineer how the hell
  their alphanumeric code assignment works? Can anyone see any logic to it?
  Can it be generalised somehow? 

- Having grown up in Islington, Blairland, London, I always wanted to
  begin my ship's log 'I grew up in quadrant 17'. Can't we think of a
  more sci-fi solution that actually works logically all over the world?
  I know the ecourier.co.uk guys were very excited by that idea when we
  talked about it. I mean - for international deliveries, NYC espcially
  (ecourier must take lots of stuff between Wall St. and the City
  of London) geocoded zipcodes are a nightmake, apparently. 

Here's a little snippet of Ian Smith's off-topic tangent from the
Multi-Registry Systems Development mailing list:
http://copsewood.net/mailman/listinfo/mrsdev 

On Mon, Jun 27, 2005 at 10:39:34PM +1000, Ian Smith wrote:
> I think quadtrees are likely the best way to express global locality,
> having explored these in depth many years ago for spatial database
> purposes, not sure if I still have those papers but now there's google
> .. anyway, these are basically just binary cuts of whatever (at least
> 2) dimensional space you want to work with, using 2 bits per quadrant.
>
> So a 2 bit quadtree has values 00, 01, 10 and 11, being (by convention)
> the northwest, northeast, southeast and southwest quadrants.  Using the
> equator and good old Greenwich pinpoints you to your quadrisphere :)
>
> Adding two more bits gives you 16 areas - just draw it the once and all
> deeper is revealed - and so on, yielding a 2n-bit integer representing
> any subdivision of (say) latitude and longitude, be it a unit of some
> (non integral) number of miles or kilometres or 'blocks' - or mm aiming
> coordinates for the neighbour's doghouse door - how many bits you wish
> significant is entirely your (local) choice.
>
> >From any quadrant you get its enclosing quadrant(s) at double scale by
> dropping 2 bits, or more detail wherever appropriate simply by adding
> more (pairs of) bits.  I once devised a packing for these suitable for
> microprocessors with like 16kB memory, but a mysql set's cheap now.
>
> Oh yes, you need to multiply by cos(latitude) to obtain squareish
> squares, and navigation at the poles may be fraught, but ah well!