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View Full Version : IKBoost problem; need advice



G3D
01-17-2007, 03:51 PM
Hi,
I've started a rigging project with IKB but don't have much experience with rigging. I have one roadblock which is really the same kind of roadblock I had when using the older IK system. I hope I'm not expecting too much out of either IK system. I'm rigging a crab-like animal, whose joints tend to bend on only one axis. Initially I thought this would be a little easier to work with since there is only one axis to rotate on at each joint, unlike a human rig.
The biggest problem is that on each limb, one joint near the base of each limb needs to rotate on an odd and very specific angle. The Bone Tools that I used on many of the other joints with success will not work in these cases. My solution was to draw a 'custom' bone at the parent of the desired joint so that it would be at the proper angle. I reparented the rig below that joint on the chain to the new drawn bone. That bone needs to rotate along its length with mean it needs to rotate on the Bank axis. I've had no luck getting IKB to set a limit for its bank rotation; even though I gave it fairly tight limits, it flails around on its bank, rotating completely outside of the limits I had assigned. Anyone know what might be wrong? Does IKB work only with Heading and Pitch?
Thanks in advance!

SplineGod
01-17-2007, 11:26 PM
Hey George,
Its hard to say (for me at least) why the issue might be. I cant tell exactly what youre trying to do. Maybe you can post a single leg with bones.
You can lock particular channels, set IK stop, fix a controller,set a controller to fk and so on to make the leg poseable. All of these can be changed on the fly as needed. IKBoost is really designed to allow you to create poses.

G3D
01-18-2007, 02:50 PM
The problem was just me working for too long. Part of it is a very serious selection bug in LW, making me have to zoom out to select anything. Selecting a bone results in selecting a light even though I'm still in the bone mode. Its pretty frustrating. Same with IKB, selection and usability in general is terrible. Anyway, here are links to a couple QT movies.

A smaller one--2.5 megs
http://g-3d.com/IKB_Success_02C.mov
And a larger one--8 megs, but you can see the setup more clearly.
http://g-3d.com/IKB_Success_02B.mov

You might remember me asking about weightmaps and rigging in other posts a while back. This is the same model I was talking about. The final will be a CC version, but for rigging and setup I'm using the standard Sub-Ds

For both limbs the entire rig is controled by the green nulls(I used custom shapes to make them easier to see)
The limb on the left moves slightly differently than the one on the right. The reason is that each bone in the limb on the right is set up in the graph editor with tension = 1 on its keys. The left limb's bones are set up in the IKB graph editor with tension = 0 This is a bit counter intuitive, but since its really the nulls that are doing the animating, it makes sense. What I'm planning on doing is finishing the entire rig--consisting of 202 bones for the whole animal--and do all my animation using the nulls as controlers. Hopefully the final animation won't be too stiff. Since this is a crab like animal, it shouldn't be too bad.
I'm planning on finishing the model in Mudbox(which is excellent) and BodyPaint.

Some thing I wished worked better with IKB:

Selecting and interacting with bones and their settings. Having to zoom way out in order to avoid selection bugs is a drag.

I wish the controler nulls could be set up to work with the sliders feature. For me the sliders allow for precise work, rather than directly selecting a controller null while in IKB mode, which is not very precise.
Anyway hope this info is usefull to someone. I'll post more about this project as it moves along.

G3D
01-18-2007, 02:56 PM
that might not be obvious: there are three levels to the IKB: the null moves each bone through the motion, but also some of the bones have children (the spines) that use their parents as controllers.