Re: pose

Darren Kelly (
Tue, 14 Oct 1997 11:54:01 +0200 (MST)

On Mon, 13 Oct 1997, { brad brace } wrote:

> (Thanks Robert;) I'm just postulating about posing out-loud.... Wondering
> if a (darkened) performance might consist of (technically detected, then
> amplified and/or illuminated) movement as a consequence of a singular,
> extended pose... and/or as a result of some impact or collision with the
> pose...

Dear Brad,

This is very easy to implement, and I use it often.
With accelerometers (very easy to implement) or velocity measurement
(more complicated) you can easily detect this state.

With accelerometers you simply assert that the acceleration signal(s)
doesn't change (within a certain tiny limit) over a few data collection
steps. You then trigger your action (lights on or whatever). The trigger
is then blacked out. You reset the trigger whenever the signals change
sufficiently (over a few time steps), and perhaps perform another action
during this trigger reset (lights off).

This way you can control a strobe effect. It is particularly suited to
dance like Australian aboriginal dance. The dance is often accompanied by
rhythm with two hardwood sticks. The dancers move from one position to the
next, freezing inbetween in time with the (tricky) sticks beat. If you
switch lights on when the dancer feezes and off afterwards you capture the
various positions. Aboriginal dancers imitate the movements of animals
such as emus this way.

You can't use "zero" signal as a test with accelerometers, as there will
always be a contribution from gravity, so the signal strength depends
on the inclination of the accelerometer, thus restricting the condition
for zero signal and the available poses.



PS: the long promised CMJ article will contrain an exhaustive list
of such MTS algorithms. I call this the MTS "freeze" algorithm.

Darren Kelly | | |
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