Buckinghamshire CC ANPR cameras

Clive D.W. Feather clive at davros.org
Thu Jan 12 10:39:13 GMT 2012

David Goodenough said:
>> So the probability of a collision is 1 - 1.14e-47, or just about certain.
> Have you factored in that most of the cars in a given area will share
> part of their number (all cars registered in Oxford in the post 2001
> scheme start OX)?

Actually, they all start O (apart from personalized registrations), not
necessarily OX.

> On a motorway this will not make much difference, in
> an urban setting it might well skew the distribution of plates.

I've assumed that the actual hash algorithm is a good one. That is, once
the reduction process (O/0/D -> O, etc.) has been done, two strings
differing by only one character are likely to have completely different

Clive D.W. Feather          | If you lie to the compiler,
Email: clive at davros.org     | it will get its revenge.
Web: http://www.davros.org  |   - Henry Spencer
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