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Troubled car maker Rover Group has worked out how to save drivers the trouble
of flicking on a heater switch when their windscreen or rear window has misted
over (GB 2 340 938). An array of video cameras, mirrors, lenses and prisms sits
over the driver to capture the view ahead and behind. The images are compared
with reference pictures stored in memory so that a signal processor can decide
when the view is indistinct, and switch on the heating and ventilating systems.
The processor has to be clever enough to avoid false readings at dusk or on
foggy days, Rover warns.