View Full Version : IK Boost Problem

Ty Catt
06-25-2009, 09:26 AM
Or at least maybe IK Boost.

Here's my situation. I got a client who loves a 3D model that WAS NOT created in a T pose.

I tried to repose the model in Modeler, but the character is clothed, and I'm getting tons of different layer poke through problems.

So can I just "rig" the model into position?

If I rig the model in it's "wrong position", apply IK Boost, then move an arm, the whole torso goes with it.

I'm betting that I'm I supposed to rest the model before IK Boost or something similar. I'm not sure. I thought when the rig is created, it is at rest!

I'm still kind of new to this, using Kurv's IK Booster tutorial. I am only having problems with this non T posed guy and I can't decide where it went wrong!

Any ideas?

Tried weight maps, still didn't do it. And Falloff Type to 128.



06-25-2009, 09:52 AM
I've got SplineGod/Kurv's IK Boost DVD - and am learning IK Boost.

I found this useful also:

He's got a specific tutorial on rig sharing which might be useful to you, shows using a different character with your rig - and the steps needed (such as resting the bones).


06-25-2009, 11:30 AM
Right, the deformation has to do with the bones and resting them (which is like attaching them to the mesh) before moving them. IK Boost really only has to do with moving the bones to pose them, the deformations are handled by the bones, not IK Boost. The mesh would deform the same way if you moved the bones with or without IK Boost.

Ty Catt
06-25-2009, 11:37 AM
OK, I see...

Here's what I'm doing...

I load the character into Layout, I add the bones the normal way (with Child Bones).

Select all the bones and hit R to activate them.

If I rotate any bone, the mesh follows.

Do I rest them somewhere in there? Aren't they rested?

Ugh, sorry to be a pest.

Never rigged before, but actually love doing it now, and this roadblock has got me stumped.

BTW, 3Dwannabe, I have the same Kurv tutorials. They are pretty darn cool, huh?!



06-25-2009, 04:01 PM
You need to define your IK chains.
If you want to move just the arm and nothing else then you need to apply IKStop to the shoulder. Do the same with the other arm and legs. Nothing you do to the rig in IKB is permanent and changing the rig on the fly is actually part of the animation process.
I have several hours of free vids on IKB here:

Ty Catt
06-25-2009, 07:05 PM
COOL! A reply from the man himself!

I recently purchased your IK Boost tutorial and it has been extremely helpful!

I actually have IK Stop on all the correct areas (shoulder / hips).

I don't know if you noticed early in the thread, I am applying IK Boost to a character rigged in Layout NOT in the classic T pose.

Does that matter?

Would the scene file help?

I thought I had the "bones at rest", but maybe not.

Is there a quick explanation as to how to know if your bones are at rest?

After you rig the character in Layout, is there another step to check your work / optimize your rig so the bones are at rest?



06-25-2009, 07:13 PM
Once the bones are in place just select all the bones and hit the r key to rest them all.
My response was mainly to your problem with the whole torso moving when you moved the arm. It shouldnt do that if the IKStops are in the proper places. The T pose or lack of it shouldnt effect how IKB works. The T pose is mostly done to help get the bones sin easier, help with deformations etc.

Ty Catt
06-25-2009, 10:07 PM

Thanks for all your help.

I understand what you mean about the T pose, I just wanted to be thorough in case that could possibly have something wrong with it.

Anyhow, the mesh is still deforming incorrectly.

I've attached the scene if that helps.

I rigged lots of other things via your tutorials with no problem.

The client really wants this model, but I can't seem to get it to behave.

Thank you!


06-25-2009, 11:30 PM
The mesh is deforming badly because its not in a T pose. If you dont use weight maps then you want to isolate the limbs from each other as much as possible which the T pose does. This helps reduce or eliminate bone cross influence which is the problem youre having.
You can fix it by adjusting the character into more of a T pose with the arms and legs spread or use weight maps. The issue doesnt have anything to do with IKBoost. :)

Ty Catt
06-26-2009, 05:21 AM
Thanks, Larry!

I'll go build some weight maps.

Also, one other questions- when it comes to rigging for IK Boost, is more bones better than less for deformation, or vice versa?

Thanks again, you have been a great help!


06-26-2009, 06:25 AM
I try to keep things as simple as I can regardless. I tend to either avoid weight maps if I can or simplify them greatly. For example the arms and legs can share a single weight map because multiple bones can be assigned to a single weight map.
I generally start out with the basic bones then test deformation before using weight maps. Sometimes I can just add a couple of hold bones and get pretty good deformations that way. Doing it that way can save alot of time when it comes to weight maps.
If the character isnt modeled well no amount of weight maps will help. Good flow is very helpful to getting good deformations. Understanding just how bone influence works etc is also essential because weight maps modify the normal bone influence.
Weight maps can really help if used properly but can also greatly complicate what would otherwise been a much simpler task.
Another advantage of hold bones is that they can be animated to help with deformations.

06-26-2009, 07:43 AM
If the character isn't modeled well no amount of weight maps will help. Good flow is very helpful to getting good deformations.

Larry - what does 'good flow' mean?

I've got a vague idea of what it means in a face with loops, but I just realized I can't exactly define the term for use in a model that will be animated.

Besides your IkBoost DVD, I purchased (but have yet to start on) your

LightWave 3D Ultimate Modeling Guide to 3D Modeling LightWave 3D 9.x Cartoon Character Modeling

LightWave 3D 9 Introduction to Character Modeling

Would there be a specific .mov sequence in one of these where 'good flow' might be defined in more detail?

Ty Catt
06-26-2009, 08:58 AM

Thanks for the GREAT advice!

I appreciate your time.

Your videos have helped me so much.

Thanks again,