#IK question
7 messages in this thread
I've got a question about IK. Let me start by giving an example. Let's say I
have a human mesh linked and all the joint parameters set. Is there a way to
move the hand and have it affect all of the parent joints up the arm, but stop
at the shoulder, so when I move it no keyframes are created for the chest ect?
That way I could animate a joint such as the jaw, but not have the head move at
all in the process. I hope I am being clear. Let me know if this makes no
sense.
Thanks
Mitch
Basically, yes. When you define your kinematic chain, anything "above"
the chain (parental) will be unaffected by any keyframes generated when motion
is solved for with IK. Anything below the chain will of course follow it's
parent.
Something as basic as a jaw I would probably keyframe by hand, FWIW.
Paul S.
Is there no way to do this using the interacive and not the follow
method? This is the only way that IK will be worth while to me on
this project. I need to be able to animate all of my chains which
are all linked to a master chain, all using IK. I have tried using
the follow technique, but it does not provide the instant feedback to
do this type of animation.
BTY, the jaw movement is far from basic. This is a VERY realistic animation of
a human head (using Bones), so the joint parameters set for the jaw are pretty
complex, much more than a simple single axis rotation.
Thanks
Mitch
>> Is there no way to do this using the interacive and not the follow method?
<<
I personally love the feel of keyframing using the Interactive
Mode of IK, it is a very "natural" way to work for me, sort of like
playing with Gumby. All of your joints (correct me if I'm wrong
Jonas) will obey their joint parameters this way *for those
keyframes*. If you then exit IK, the keyframes will be saved, but
the "tweening" done by 3DS/IK will NOT obey your joint parameters,
except by chance. You MUST use the follow method for IK to solve for
joint parameters accurately.
One solution for you might be to super-tweak your animation,
maybe setting a keyframe every couple of frames in Interactive Mode.
Use more keyframes to get tighter control when there is motion that
might be tweened incorrectly by 3DS. I assume you'll lose some nice
abilities such as setting joint precedence, I'm not sure. Jonas?
Good luck! What's the project for? My dad is an orthodontist…
I used to make retainers for him back in high school. <g>
Paul S.
Hi Mitch and Paul,
<< I have tried using the follow technique, but it does not provide the
instant feedback to do this type of animation. >>
I've been animating a stage scene with several musicians lately. I
also needed more visual feedback on the interaction of the characters
to each other and to stage props while tweeking joint parameters and
precedence. I ended up linking all of the major elements of my scene
to a dummy and jumped into IK. Lo and behold, I had several human
meshes and stage props all visible in the Interactive Mode. This
allowed me to still use the follow method but also allowed me to use
Interactive to view my results of Joint Parameter modification
without having to exit back to the keyframer.
I'm still a very strong advocate of the follow method.
jonas
>> ended up linking all of the major elements of my scene to a dummy <<
Jonas, great tip, thanks.
TedB
-Ted Boardman
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Hi Mitch,
<< Is there a way to move the hand and have it affect all of the parent joints
up the arm, but stop at the shoulder, so when I move it no keyframes are
created for the chest ect? >>
Yes.. you would use the follow method and not the interactive method. Please
download the following file for an additional tutorial on IK..
File Info for FLIP.ZIP
Section: Mesh/Project Files Contributor: 73172,1351 Size: 95951
Submitted: 10/21/94 Type: Binary Accesses: 15
Title: IK Backflip
Keys: IK FLIP R4
This is an example of using IK a number of different ways. A woman doing a 1
1/2
back flip off of a diving board. There was no keyframing of the board or the
woman
on my part. All movement solved for by using IK. This zip includes a solved
version
and an unsolved version so that the R3 users can compare the two files. Note
also
the flip.zip (a flip.fli) in the Animations section of the lib. IK'd and
uploaded by
jonas.