[PD] physical modelling/general pd

[Jack]

Hello Julian,
I have done a wind chime there is 2-3 years ago with PD/GEM/PMPD. I  
used PHP to get on the web the value of direction and force of wind  
in differents cities in Europe.
Here a link for a video without sound (i remove it from the export) :
http://djrayban2.free.fr/Movie/windChime.mov
++

Jack

Le 8 août 08 à 12:16, cyrille henry a écrit :

> hello,
>
>
> Mark Sexton a écrit :
>> Hi Julian
>> Building a physical model of a wind chime might be easier than you  
>> think, if
>> you use modal or banded waveguide approaches to physical modelling  
>> rather
>> than the brute force approach of pmpd.
>
> pmpd aim to model the movement, not the sound.
> the hamer and the tube of a simple wind chime could be modeled with  
> about 10 masses.
> To create a physical model of the sound is very different.
> but you need both to model the wind chime.
>
> Cyrille
>
>
>
>
>
>
>
>>
>> If you think of the wind chimes should as stiff bars, banded  
>> waveguides
>> would be ideal and are much more computationally efficient to  
>> implement than
>> brute force approaches: a resonant filter and delay per mode you  
>> want to
>> synthesis.  I'd recommend perhaps starting with a simple modal
>> implementation using filters and build up from there. This paper  
>> gives a
>> good introduction:
>> http://www.cs.ubc.ca/~kvdoel/publications/modalpaper.pdf
>>
>>
>> If you're not familiar with modal synthesis and banded waveguides  
>> there's
>> plenty of information online and Perry Cook's book gives a good  
>> overview of
>> a range of approaches to modelling.
>> http://www.cs.princeton.edu/~prc/AKPetersBook.htm
>>
>> Some starting hints if you want to go down this route:
>>
>> 1. Create an impulse: a buffer of noise or single sample impulse
>> 2. Feed this into perhaps 5 band pass IIR filters with a very  
>> narrow Q,
>> these will provide your resonant modes for each chime.
>> 3. The frequencies of these filters will probably be non-integer  
>> multiples
>> of the fundamental, eventually you can get these by analysing an  
>> actual wind
>> chime, but if you wanted to build a proof of concept now then  
>> these are
>> typical modes of an aluminium bar (you can find further modal  
>> frequency
>> ratios in the Csound manual):
>> [1, 2.756, 5.423, 8.988, 13.448, 18.680]
>> 4. Scale the outputs of each of the resonant filters as  
>> appropriate, this
>> should be straight forward once you've done an audio analysis of  
>> your wind
>> chime.
>>
>> At this point you have a simple resonating model of a wind chime.
>>
>> 5. Perhaps replace the impulse: you can remove the resonant  
>> components of
>> your wind chime recording and this will leave you with the  
>> original noise
>> impulse. Using this to trigger your model should help improve  
>> realism.
>> 6. Create a banded waveguide version, by adding feedback delays  
>> for each
>> mode. (have a read of this paper and a look at Fig. 4):
>> http://soundlab.cs.princeton.edu/publications/1999_icmc_bar.pdf
>>
>> There's a few further tweaks and improvements that can be done, but
>> something along these lines should give a good result, be fairly  
>> easy to
>> implement and run more efficiently than brute force.
>>
>> Happy to chat more on or off list on the physical model side or  
>> algorithmic
>> composition side, but you may find it easier than you thought once  
>> you get
>> going.
>>
>>
>> All the best
>>
>> Mark Sexton
>> Senior Lecturer
>> MSc Computational Sound
>> University of Portsmouth
>>
>>> Message: 2
>>> Date: Thu, 7 Aug 2008 12:30:51 +0100
>>> From: "Julian Brooks" <julian.brooks at virgin.net>
>>> Subject: [PD] physical modelling/general pd - mentor/tuition sought
>>> (money offered)
>>> To: <pd-list at iem.at>
>>> Message-ID: <000001c8f881$0d514a40$27f3dec0$@brooks at virgin.net>
>>> Content-Type: text/plain; charset="us-ascii"
>>>
>>> Hi all,
>>>
>>>
>>>
>>> I have a 12 month project as part of a masters degree, where I  
>>> wish to build
>>> a physical model of a wind chime.  I then want to use the  
>>> interface to play
>>> some of my indeterminate compositions.  I was going to attempt it  
>>> for my
>>> undergraduate degree but realised that it was far too complex for  
>>> the
>>> available time that I had then.
>>>
>>>
>>>
>>> I have been using pd for a few years now, list lurking, working  
>>> through
>>> basic examples, building simple tools, using other peoples  
>>> patches etc.  But
>>> this is too complex for me to do on my own.  At my uni there  
>>> isn't anyone
>>> with better skills than me and I don't know of any local fellow  
>>> patchers.
>>>
>>>
>>>
>>> Now as a musician, when I need to up my skills, I will look to  
>>> find some
>>> lessons when I have got as far as I can on my own.
>>>
>>>
>>>
>>> So here goes...
>>>
>>>
>>>
>>> Is there anyone with an hour a week to spare who can offer some
>>> mentoring/tuition for what we can deem to be the 'going rate'.  I  
>>> am more
>>> than happy to do this remotely/online, I'm sure there is a way we  
>>> can work
>>> it out.  There would be full credit given of course.
>>>
>>>
>>>
>>> Pmpd seems like the way to go with this.  I have worked through the
>>> examples, and, although I have my eye on what examples I would  
>>> presume to be
>>> the best starting points, I'm struggling to get started.  The  
>>> physical
>>> modelling is where I first need to start but there's loads of pd  
>>> stuff I
>>> would like to be able to work through with someone, so this could  
>>> be a (me
>>> love you)longtime regular small money earner, if anyone's  
>>> interested.
>>>
>>>
>>>
>>> I am in Hebden Bridge, West Yorkshire, UK, by the way.  Any  
>>> pd'ers local,
>>> give us a shout.
>>>
>>>
>>>
>>> Best wishes to all,
>>>
>>>
>>>
>>> Jb
>>>
>>
>>
>>
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