Buckinghamshire CC ANPR cameras

[Ian Mason]

On 6 Jan 2012, at 17:03, Ben Laurie wrote:

> On Fri, Jan 6, 2012 at 4:48 PM, John Wilson <tugwilson at gmail.com>  
> wrote:
>> Is there a standard "depersonalisation" algorithm? If so anybody know
>> what it is?
>
> No. Indeed, in general, it is not possible to "depersonalise" and
> retain any usefulness in the data.
>
> So step 1 is probably to find out WTF they're actually doing.
>

It depends. If they are strictly monitoring traffic flows and journey  
times then all they have to do is assign a unique journey number to a  
set of records for a vehicle and drop/delete the registration number  
when the journey seems complete. Each time the vehicle starts a  
journey it gets assigned a new unique journey number so that there's  
no link with previous journeys for the same vehicle and no record of  
the registration number at all once a journey has completed. Obviously  
there's detail to work through such as: a vehicle enters the area, is  
seen by ANPR on entry, then parks up for several days and isn't seen  
by a second ANPR camera; at what point do you delete the partial  
journey record that will, of necessity, still contain a registration  
number.

Ian