light function

Apr 13, 2012 at 12:26am

light function

hi,
does anyone have any method or any tool or any idea for remove some points in a function ?

if i have 100 points (like in motion capture), haw can i have less point ?

like a factorization or a simplification, in order to keep almost the same form of the function
even if the form is not exacty the same… like a smoother

i think it’s a known problem in math..
thanks

#62931
Apr 13, 2012 at 10:37am

Is there any information in this thread that will help? It’s about interpolating between points in a function:

http://www.cycling74.com/forums/topic.php?id=25702

Brendan

#227159
Apr 13, 2012 at 12:03pm

thanks, i’ve already seen this post,
but it’s about smoothing betwen points, not removing some of them (by the way, safunction is great, i’m waiting the pattr or write-file implementation)
ej.function allows removing same y point with different x, but it’s not enough

#227160
Apr 13, 2012 at 3:26pm

Can you ‘remove’ points in realtime, with [snapshot~] or [speedlim]?

Chris Muir’s response here has kind of gained legendary status:

http://www.cycling74.com/forums/topic.php?id=15180

Brendan

sorry that my maths is too weak to help directly :(

#227161
Apr 13, 2012 at 3:58pm

yes, i’ve implemanted a speedlim
smothing could be nice to, but it still record a lot of point..

My goal is to record data and allow a nice way to edit it simply. Like for making a score from an improvisation,
with number boxes wich are mapped to a numerical music or a visual instrument, lights or automates.

in adobe after effect for exmaple, it’s possible to smooth a function by removing keyframes and keep almost the same form of the interpolation.

after you move, change value, copy-paste keys,
it could be greate to do the same with some values in max ! by reducing the number of points and why not quantize thems, in a function curve.

I hope some algorythms already existing.. or i have to find great developers who can help me to do this tool. I’m sure it miss for music writers

cheers

#227162
Apr 13, 2012 at 6:48pm

One simple way to approach this is to drastically subsample, taking the maxima and minima per sample frame. For example, if you were taking decimating (ten data points to two, in this case) you would take the highest and lowest of the ten points and output those as your two. I’ve used this technique to draw audio waveforms which were drastically compressed from the real audio file.

#227163
Apr 14, 2012 at 6:55pm

you could work with two [function] objects, one is the original. Grab every X number of points from the original one and put it into the new one, voila, downsample. This doesn’t take the values into account, so you can’t guarantee the same rough overall form, but it might be a start.

#227164
Apr 14, 2012 at 10:44pm

an idea is to estimate Y-delta between two consecutive points (A and B). If the Y-delta bewteen the B and C points is almsot the same (with a tolerance), i estimate Ydelta between B and C and remove the B point. then estimate Ydelta between B(old) and C, if it’s not almost the same, i keep C and estimate Ydelta between C and D ….

of course it could works only if points have a regular space between them on the X axis.
I’ll maybe try this, if i can’t find a better solution instead the chris muir sample frame one.
Seejayjames, i think your way gives the same result than speedlim during recording

Thanks a lot for your intereset

#227165
Apr 15, 2012 at 12:56am

it’s a proposition
it don’t keep the max and the min :(
but estimate difference between points and keep some of them wich are really different from the lasts
maybe cumulate chris sampleframe method with this one…

– Pasted Max Patch, click to expand. –
#227166
Apr 16, 2012 at 11:37am

a bit more effecient

– Pasted Max Patch, click to expand. –
#227167

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