>It occurred to me that the availability of low cost video cameras in
various
>forms (serial port, parallel, USB, separate video ...) should allow a
>reasonably low cost solution where the camera monitored a target and
>detected head orientation. This could still include a head mounted target
or
>source but this could be more discrete and if active it could be infrared
>and pulsed. While this sounds eminently achievable there would almost
>certainly prove to be "more to it" than meets the eye at this stage. Such a
>system is notionally more expensive in material cost than a headpointer /
>beam system but would be more flexible, more easily adapted to related uses
>and less user intrusive.

Using a webcam type device looking over the top of the book at the person,
how would the following work out?

If the person is dark haired this may be easier, but with using IR
sensitivity could possibly work with anyone - sense the area and position of
the face e.g. look towards ceiling (or straight at camera) as you suggested
to "start command" and then rock head to one side or the other to turn page
in same direction as head rock. Sense head position by light area of face.

If the person has reasonable limb mobility it may be possible to provide
additional commands by moving left or right arm after using head movement
"start command". Sense it is an arm by long thin object instead of round
blob object you would use for face. By seeing if there is a line on the left
or right side of the image you may get more commands. If you can distinguish
between low lifted arm and high lifted arm you could have two commands per
arm.

Doing it this way the person would not need to have any headgear at all, let
alone be connected to anything.

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