[osg-users] osgAnimation Help

Ugras Erdogan ugraserdogan at yahoo.com
Sun Mar 29 07:28:02 PDT 2009


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>
> To: OpenSceneGraph Users <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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-- +33 (0) 6 63 20 03 56  Cedric Pinson mailto:mornifle at plopbyte.net http://www.plopbyte.net


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