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Is Inverse Kinetmatics the culprit?

Eris Fallon
Registered User
Join date: 27 Sep 2006
Posts: 11
03-31-2007 09:50
I have a number of two frame static poses that I created in Poser with the use of IK, and now I'm trying to add in a little bit of subtle movement to them but I'm not getting the results I was hoping for.

I keep IK on while I move the rest of the body parts since my anims require that the hands and feet stay perfectly stationary, and only the rest of the body move. The first time I tried this, only the arms (shoulder up) were moving in any way, and the hands weren't staying locked in position. The rest of the body wasn't moving at all, even though every joint had some subtle movement added to it. I tried turning off IK and re-importing, but there was no difference. The feet did seem to stay locked though (like they should), but that's probably because nothing from the torso down was responding.

The second one was similar, except that there was a bit more movement throughout the body. Again, hands and feet were locked with IK while the rest of the body was tweaked. This time though, I only moved the hips to get the joint changes I wanted. It looked great when running in Poser, but in the preview (and the uploaded anim), the feet where sliding around instead of staying put, and the hands were translating too, but not by as much. The rest of the body seemed to be behaving properly, except that when it moved, it took the hands and feet along with it.

This sounds like an IK problem, but I'm not sure. I've tried turning off IK, altering the joint angles manually, and even breaking the splines on every keyframe, but still nothing.

Even if no one has answer for why this is happening, maybe someone has a suggestion for creating an animation that locks hands and feet (a la IK), but will allow me to manipulate the rest of the body ... and then be understandable by SL.

Btw, my second frame takes care of all of the first frame zeros, so that's not an issue.

Thanks! :)
RobbyRacoon Olmstead
Red warrior is hungry!
Join date: 20 Sep 2006
Posts: 1,821
03-31-2007 11:20
I don't believe that inverse kinematics is causing your problems... That is only a tool used within Poser and only the resulting movement is recorded in the exported .bvh file. I have successfully used IK for animations, which just adds to my belief that there is another reason for "sliding feet syndrome".

I apologize, I am too tired right now to find it, but I know that I have read other posts in this forum about the causes and resolution to sliding feet. Might be well worth searching again and adding feet to the query.

Also, hopefully by adding my "less helpful than I would like" reply and bumping the thread someone who knows more will jump in :)
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RobbyRacoon Olmstead
Red warrior is hungry!
Join date: 20 Sep 2006
Posts: 1,821
03-31-2007 11:23
Hmmm.... I would not have expected this, but Mickey McLuhan reports that she does in fact have problems with odd behavior when using inverse kinematics in Poser.
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Mickey McLuhan
She of the SwissArmy Tail
Join date: 22 Aug 2005
Posts: 1,032
03-31-2007 11:27
It may be that the hips are moving a little and dragging the feet with them, due to differences in size of the AV or other variables. That's the only thing I can think it may be.

Edited to add:
LOL. Yes, there are occasional problems in the McLuhan home when it comes to IK, but I believe that the OP covered my solutions, so I'm useless there! *grin*
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*0.0*

Where there's smoke, there isn't always fire. It might just be a particle display. ;-)
-Mari-

Dylan Rickenbacker
Animator
Join date: 11 Oct 2006
Posts: 365
04-01-2007 08:25
Hi Eris, I asked a similar question a while ago and got a very helpful reply from Johan Durant, check it out:

/52/18/167974/1.html
Pulaski Fizz
Registered User
Join date: 5 Jun 2005
Posts: 110
04-03-2007 13:02
I have had this issue. IK is not to blame. I have messed with it and with or without IK i get some wierd movement.

I set up frame two as I want. Then i go out to say frame 5 and set it up. When i check 3-4 they are all messed up and twisted. If i continue on there is no further issue and just have to manually adjust frames 3-4. I can't seay I know poser well, but this is my main issue with it not doing what i want.