[osg-users] osgAnimation Help

Janusz janusz at 3dcalc.pl
Sun Mar 29 09:07:20 PDT 2009


Ugras: CCD is one of the method to be used. Quite fast and does not 
require complex math. Another method you could use is the Selectively 
Damped Least Square method for Inverse Kinematics (by S. Buss), 
pseudo-inverse jacobian, etc. This one I think if you google a little 
bit for this one you may come across a source code by the author.

If you are after fast math and human limb IK, there is the IKAN solver 
from the univ. of Pensylvannia.

The SDLS paper:


      /http://akpeters.metapress.com/index/K301108177Q2170V.pdf///

---
Janusz Goldasz



Ugras Erdogan pisze:
> Hi Cedric,
>       At the moment I'm in need of a IK solver for my project. Simply 
> I know the initial position of my mechanical manipulator and final 
> position of it, and I want to know what should the angles of joints be 
> in order to achieve the movement to the final position with minimum 
> error. Final position of the mechanic manipulator may be time 
> dependent (this is important) and for the moment let's assume that the 
> initial position is time invariant. As I am very new to osgAnimation 
> kit (not to osg), I'm currently studying the example codes. And I 
> couldn't have noticed any IK solver to achieve the task (as you 
> mentioned) yet. Referring to IEEE TRANSACTIONS ON ROBOTICS AND 
> AUTOMATION, VOL. / I , / NO. 4, AUGUST 1991, Li-Chun Tommy Wang and 
> Chih Cheng Chen  and other papers, the optimization algorithm named as 
> Cyclic Coordinate Descent seems suitable for the task at hand. It is 
> an iterative optimization technique that calculates the angles of the 
> joints of the mechanical part to achieve the movement towards the 
> final position with minimum final error.
>       I want to know your opinion (and all other's opinions) on the 
> subject whether I'm on the right path or I'm missing something else...
> Best regards,
> Ugras
>
> *From:* Cedric Pinson <mornifle at plopbyte.net>
> *To:* OpenSceneGraph Users <osg-users at lists.openscenegraph.org>
> *Sent:* Sunday, March 29, 2009 4:02:34 AM
> *Subject:* Re: [osg-users] osgAnimation Help
>
> Hi Ugras,
> There is no IK a the moment, for all others points Alberto tells 
> everything i would say.
> If you want to add IK to osgAnimation i will be happy to discuss about 
> it with you.
>
> Cheers,
> Cedric
>
> Ugras Erdogan wrote:
> > Thanks for your replies Alberto, I'll take a look at the bundled 
> examples and contact with Cedric Pinson for the IK issue...
> > Regards,
> > Ugras
> >
> >
> >
> >
> > ________________________________
> > From: Alberto Luaces <aluaces at udc.es <mailto:aluaces at udc..es>>
> > To: OpenSceneGraph Users <osg-users at lists.openscenegraph.org 
> <mailto:osg-users at lists.openscenegraph.org>>
> > Sent: Saturday, March 28, 2009 4:31:23 PM
> > Subject: Re: [osg-users] osgAnimation Help
> >
> > Hello Ugras,
> >
> > El Sábado 28 Marzo 2009ES 13:20:44 Ugras Erdogan escribió:
> > 
> >> Dear all,
> >>      I've been trying to perform a skeletal based animation for a mesh
> >> model and rather new to osgAnimation nodekit. 1) Is it possible 
> with osgAnimation toolkit? Or should I refer to osgCal wrapper?
> >>   
> >
> > Yes, you can do it with osgAnimation.
> >
> > 
> >> 2) Should I prepare the bone hierarchy and attach it to the mesh 
> model in a software
> >> (skinning) such as 3DS max and then import in osg or all these can be
> >> readily done in osg?
> >>   
> >
> > You can do it in both ways..
> > 
> >> 3) If the above procedures can readily be done via osgAnimation, 
> what is the deformation rule for the models ie. how do the
> >> inverse kinematics are calculated? And for the deformations while 
> animation
> >> is it just enough to control the bone positions?   
> >
> > I think IK is not implemented yet. Cedric Pinson can tell you more 
> about this.
> > As for the deformations, they are calculated with the weights of the 
> mesh plus the bone transformations.
> >
> > 
> >> 4) Is there any good tutorial on the subject besides the bundled 
> osg codes for a new starter in
> >> osgAnimation nodekit I'll be very pleased if you reply...
> >>   
> >
> > I'm afraid this is the only documentation available, in addition to 
> the doxygen guides. However I must say that the osgAnimation examples 
> are very instructive.
> >
> > Regards,
> >
> > Alberto
> >
> > _______________________________________________
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> > 
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> >
> >
> >
> >        
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>
> -- +33 (0) 6 63 20 03 56  Cedric Pinson mailto:mornifle at plopbyte.net 
> <mailto:mornifle at plopbyte.net> http://www.plopbyte.net
>
>
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