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
hashes.
--
Clive D.W. Feather | If you lie to the compiler,
Email: clive at davros.org | it will get its revenge.
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