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nemirc
06-16-2003, 04:36 AM
Hello everybody.

I heard somewhere that on 1997 someone presented a paper at SIGGRAPH that discussed a way to create a muscle system.
I need to get my hands on the "theory" of muscles ASAP because I will develop a college project based on that math theory. The thing is that I've been searching everywhere and I haven't had any luck.

Do you happen to know where can I find it?

Thanks

MDuffy
06-16-2003, 06:01 PM
I don't know about a SIGGraph paper, but this is one of the best papers I've run across on muscle systems. Check out is PhD work on "Anatomically-Based Human Body Deformations"

http://vrlab.epfl.ch/~aubel/

Cheers,
Michael Duffy
mduffy@ionet.net

Lyr
06-16-2003, 07:16 PM
Here's the paper: http://www.accad.ohio-state.edu/~smay/Human/human.pdf

cgcreator
06-29-2003, 10:38 PM
Looking at this paper is really interesting, now it has got me wondering if I can convert their formulas over to some Maya MEL... I trying to do it but i am having some problems... ok if you look at Siggraph paper;

Siggraph 97 Paper (http://www.accad.ohio-state.edu/~smay/Human/human.pdf)

On page 4 there are a list of formulas to figure out the muscle budges.

First they say the axes lengths are 2a, 2b, 2c, so i set those up in MEL.

$a = Muscle.scaleX/2;
$b = Muscle.scaleY/2;
$c = Muscle.scaleZ/2;

then they say that volume is calculated by doing this; v = 4(pi)abc/3

$pi = 3.1415926;
$v = (4*$pi*$a*$b*$c)/3;

Then it asks for ratio: r = a/b

$r = $a/$b;

Then it gives formulas to calculate the new $b and $a when $c is changed;

$b1 = sqrt((3*$v)/(4*$pi*$r*$c));
$a1 = $b1*$r;


So now $b1 is the new scaleY and $a1 is the new scaleX. But when I reapply those numbers back into Muscle it goes haywire. The reason for this is cause by it updating the X and Y it thus changing the numbers in the volume and the ratio. I think the volume and ration number only need to be calculated once and thatís all. I mean rather than using variables to calculate the volume and ratio I could just plop numbers in there but I would rather have it grab those numbers when I add this function to the muscle. Any help on doing this would be great

larryvm
06-30-2003, 02:00 PM
you must not calculate the ratio and volume, you must create 2 attributes, one for the ratio and other for the volume,

and you only must calculate the

$a and $b

in this way
$pi=3.14159
$b1 = sqrt((3*muscle.volume)/(4*$pi*muscle.ratio*$c));
$a1 = $b1*$r;

you can look mi first muscle system, a mel script, you only have to select to joints and type

musculo musclename
and the script made a new sphere and its muscle expresion

was my first muscle scripts and it`s based in the 97 paper

you can too look my new muscle plugin version in

cgtalk post (http://www.cgtalk.com/showthread.php?s=&threadid=72361)
based in the aubel page docs

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