[PD] object opposite of change

[Csaba Láng]

Chuck,

thanks for the hint, sounds good. I will give a try tomorrow, but already
started to have some other solutions, and I played with time delay. I mean
under it to compare XYZ coordinates in time, if delta is close to the
noise, than I expect that the object (hand) is still.
However, there are bigger problems, as the hand disappears if the hand
touches the background, in this case I have a lost hand. Assuming that I
lost on the very last position, just before touching the wall, I can get a
quite close parameter of the hand.
Still need some tests, but together with yours probably can have a better
assumption.

Best,
Popesz

On Sun, Feb 2, 2020 at 12:56 AM Charles Z Henry <czhenry at gmail.com> wrote:

> Hi Popesz,
>
> At least on kinect, there's always a bit of noise in the tracking.
> The change from frame-to-frame will never be exactly 0, so you need
> something that acts more like a threshold.
>
> One place to start would be collecting some data on the amplitude of
> the noise when you're doing what you'd consider standing still.
> For one dimensional data, you just want to see how big is the typical
> value of |x(n)-x(n-1)|.  For more dimensions, you need sqrt sum of
> squares on the differences
>
> Then, I'd probably give it a exponential decay weighting and compare
> against a threshold that is just some factor larger than the basic
> noise amplitude.
>
> 1-D:
> [r coordinate]
> |
> [t f f]
> X
> [- 0]
> |   [r fb]
> |   [* 0.9] or some other factor <1
> [+ 0]
> |\
> | [s fb]
> |
> [expr $f1 < 10]
> |
> [select 0 1]
>
> My kinect data is all over the place.  The device is really sensitive
> to lighting, background detail, and so on.  You should consider that
> the noise may be larger sometimes depending on where you're using the
> sensor.
>
> Chuck
>
>
> On Sat, Feb 1, 2020 at 2:58 PM Csaba Láng <langcsaba at gmail.com> wrote:
> >
> > Dearest list,
> >
> > is there any object which only gives me a value from a constantly
> changing random numbers when it stops for a while, let's say for one second
> or so?
> > I am looking for the parameters of tracking hands from Kinect like
> motion detector when the hands stops on an object for a while.
> >
> > Best,
> >
> > Popesz
> > _______________________________________________
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