[Talk-GB] mapping tunnels

Thom Shannon thom at glow-internet.com
Fri Sep 28 13:14:38 BST 2007

actually ASN looks a bit smarter than that.

Here's another crazy idea. Use a video camera close to the road (I have 
a bullet cam that can be mounted on a car) then pattern match the images 
to track motion (like an optical mouse does) then combine that with a 
trace from a digital compass. Then by taking gps readings at either end 
of the tunnel you can calibrate those traces to counter cumulative 
error. You should then be able to get a really accurate trace.

Thom Shannon wrote:
> Isn't ASN just a compass?
> Nick Folwell wrote:
>> I have no idea if this would work, but...
>> Some TomToms have something called ASN - "Assisted Satellite Navigation". It
>> basically keeps you navigating even if it loses the signal, eg in a tunnel.
>> I think it uses tilt switches or similar to work out which way you're going.
>> And you can get the Event_Logger software for TomTom, here:
>> http://web.tiscali.it/macri/Event_Logger/
>> Now if you went through the tunnel with ASN turned on, and Event_Logger
>> logging - would it log where TomTom "thinks" you are?
>> Nick
>> Nick Folwell
>> nick.folwell at btinternet.com
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