Ask Slashdot: How Can a Blind Singer 'See' the Choirmaster's Baton?

New submitter krid4 writes "Question from a blind friend: 'My ears replace my eyes. However, when it comes to the very moment of starting, or the change of tempi, my start will always come too late. Neither tuning in with the voices around me, nor listening to the moment of their breathing-in helps to solve this problem. Fancy that it might be possible to produce tactile pressure or even lines at the top of my right hand, head or body. Even pulses would do, because what finally counts is the moment of the 'beat' produced by the choirmasters baton.' What simple, possibly DIY solutions are possible? It would help many blind chorus singers."

Re:motion tracking video

[femtobyte]

What part of this is hard? Cheap webcam? Bright-colored foam ball? Earpiece? Software to coordinate these?
Though image recognition in general, uncontrolled conditions is extremely hard ("here are snapshots of random traffic; identify the location of all signs, pedestrians, vehicles, and obstacles"), specialized tasks under controlled conditions ("there is one saturated red dot in the picture, between 30 and 50 pixels wide; find it.") are trivial to implement. If I was asking for software that could take any random photo of a choir and figure out where the conductor and baton were, that would be "flying car" hard; but, by reducing to a much simpler and well-controlled problem ("find the known-color, known-size spot"), the task is trivial (select all pixels within appropriate color range; apply dilation and expansion morphological operators to select the right size range; return the centroid of remaining pixels --- easy-peasy).