Buckinghamshire CC ANPR cameras
Roland Perry
lists at internetpolicyagency.com
Sat Jan 7 09:27:21 GMT 2012
In article
<AFD1C8AA-C7DC-4F81-A66F-C32CA7ED0B2A at sourcetagged.ian.co.uk>, Ian Mason
<ukcrypto at sourcetagged.ian.co.uk> writes
>>> 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.
aiui the Trafficmaster system (blue cameras) works a lot like this.
>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.
About an hour after last seeing the plate would be plenty if you are
looking at the "flow" of traffic.
--
Roland Perry
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