View Full Version : IK/FK Rigs in to MB -> IK/FK Rigs out of MOTIONBUILDER

solar power
07 July 2003, 02:54 PM
I am very interested in understanding the steps required to import an IK/FK Rig into MOTIONBUILDER, Charachterize, Animate, Plot, then Export (or Save as, or Save Selection) a fully functioning IK/FK Rig back to another 3D app.

In my case I've been trying to get animation on an IK/FK Rig back into LightWave, but to no avail. I've been unable to 'Plot' animation on anything except a skeleton (Full FK). It seems even with an FK Rig, models that have been animated in MB behave quite differently than an FK Rig animated completely in LightWave.

In an FK Rig animated in MB that has been imported/merged back to LW, the 'Reference' null(root), or anything besides the skeleton remain at 0,0,0 offering only global translation & rotation. This is quite different from a model animated in LW.

In an FK Rig animated in LW, the 'Reference' or root would remain connected/aligned to the skeletons global position and rotation.

So unless the animation from MB is 'Plotted' to not *only* to the skeleton but also the corresponding nulls, targets, and goals that make up the IK in the IK/FK Rig, then there is no way that an IK/FK Rig will function. After the mesh and skeleton have been correctly animated in MB, and the animation data has been 'Merged' with the Model/Rig in LW, all of the Rig's IK functionality remains positioned at 0,0,0 causing severe deformation to the skeleton and mesh that is trying to calculate incompatible IK/FK coordinates at the same time.

So, is it possible to have a Rig that will retain its IK functionality after being animated in MB? If so, what needs to be done during the 'Chararcterization' process to ensure that the rest of the RIG gets animated??

Many thanks for any ideas or insight. Peace.

07 July 2003, 01:33 AM
MB animation is baked onto the bones, so once back inLW, this is similar to FK.

What you might want to try is this:

Import your scene into MB, and position/rotation constrain (whever is needed) your IK nulls to the MB control rig or the MB skeleton.

Plot everything and bring back to LW, then get rid of all the bone animation, and turn on your IK. The goals should move, but since the MB rig is very complex, I doubt that your character will move the same.

CGTalk Moderation
01 January 2006, 05:00 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.