Avoiding Bone poping in IK chains
p2design writes:
Here is a short tip video on how to fix rotation popping in bones IK chains. This is a rapid overview of one of the topic I’ll deal with in my next course.
p2design writes:
Here is a short tip video on how to fix rotation popping in bones IK chains. This is a rapid overview of one of the topic I’ll deal with in my next course.
Hi pierrick thank you for the tutorial. Have you test exporting your rig to external game engines such as Unity or Unreal? will this setup transferred via FBX?
When you export to unity animations are baked to the skeleton, meaning every bone is keyframed. Constraints are not transferred but the animation will look the same due to the baking. To have Ik in unity you need to set up an Ik system in unity itself which is an entirely different thing.
Not this BS again and pseudo solutions for pseudo problems.. To clarify:
By making the leg 5% stretchy and copying rotations, you make the end of foot not correctly follow the control bone. This can lead in foot not aligning with ground or obstacles. By removing one “problem”, you introduce another (a lot severe one).
The correct way is not to rig straight chains in first place, always keep them bent a bit. And tell animators to not be idiots so they don’t animate control bones below ground or without easing. This fixes most of it.
In more advanced rigging apps the solution is to have dampened joints (the leg reaches it’s precise destination with delay, prevents sudden acceleration movements anywhere in the rig). But this is difficult with Blender (possible with soft-body and multiple rig objects to avoid stupid dependency issues).
You cannot have the IK foot follow correctly and not having “pop” at the same time. The job of IK is to place the end exactly where it needs to be. If you break this, the rig is no use to an experienced animator, because it doesn’t do what is expected. The job of FK is to control rotations precisely, and that’s why rigs should have blending between these two. This allows full control and correct results.
If you intentionally animate a leg pop, and make the rig in a way to be super obvious, there should be a leg pop. Making the rig not follow what it is told is a road to hell and bad rigging practice.
Experienced animators in a studio would be angry for messing with riggs like this.
Hey John, why the tone? :)
Things aren’t that bad!
In rigging there is no single formula and good ideas are welcome.
I recently participated in the development of rigs for a renowned French studio. At the supervisor’s request I proposed an option that looks like this one and apparently the animators appreciate it!
Let’s note that this option already exists in the “pitchipoy” rig and I think it’s a very good thing.
The tone is because I am frustrated and I no longer know how else to put it to be impactfull. Sorry if that took you off-guard, it’s not only your fault but others do it as well.
It’s because the “PRO” tips in the title, and the content actually being Noob Tips. 90% of the Blender demographic watching these tutorials are inexperienced young people that learn to 3D so they are unable to distinguish right from wrong. It’s very toxic to feed them bad practices.
Just look in the past. CGCookie advising on making pole targets with double IK: https://youtu.be/f5HoJcOetK0?t=22m48s. And people do copy it and make other videos with same setups: https://www.youtube.com/watch?v=S0VS0IVylzg. Blender Guru didn’t even mix glossy materials through Fresnel and after the years admitted the mistake, many people followed that. These are just some of the big examples from “trustworthy” “pro” artists. It then takes years to debunk that. This leg pop “problem” is just another chapter.
It is not true that ‘things aren’t that bad’ and ‘there is no single formula’. There are objectively bad results from this setup. This is how it should work: https://www.youtube.com/watch?v=BNH7XBGKgys. You can see it is correctly damped and the end point correctly follows the control point. I hope maybe in time you can accept this and you see the difference: https://imgur.com/fSi3bzE. I don’t know how is this a “pro” tip.
I agree that good ideas are welcome, but good ideas don’t break the rigs and make it disobey what you tell it to do. The IK follows the foot ctrl in unpredictable way. And it is so much it makes visual impact when dealing with object/ground collisions.
I know Pitchipoy has “Soft IK” buzzword inside, but that does not make it right. Inside Blender community there are so many bad practices and workarounds, you cannot trust anything and you need to test.
If your animators appreciate this solution, I am sorry but I don’t have high meaning of them.
Until Blender has true SoftIK solver to offer, there can be only workarounds. This pseudo-solution is a road to hell (what I wrote last time) and I would expect an artist making “pro-tips” to know this.
Hi John,
First words I read today are yours and they make me happy.
Thanks for the challenge and I appreciate you’re honesty during these exchanges.
Looking forward for nes reviews ;)
Can you please explain why double IK with pole target rig is bad? I learn rigging currently and can’t find information on this
Well, using pole target is the best way to control an ik rig.
So you should by default use it.
the thing is that with a 2 bones IK chain you should be able to deal with knee or elbow orientation in most cases without a pole target by simply rotating the arm or thig….
It’s easier in animation to deal with rotation curves than the position of the pole target in the 3D space.
But, since I’ve been animating a lot lately, I think I will get back to using pole target as they are more stable.
Hi Sam, thanks for your support.
Just fixed the problem and will post the tutorial soon.
Hi John,
Well, Currently, I don’t get that much lake of accuracy with this setup and as a bit experienced animator I’ve spent more time working on my IK curves to avoid poping than on foot position.
The problem occur when you will move the pelvis.
To fix this, you’ll have to constraint the IK driver bone with a stretched bone that goes from the pelvis to the actual foot so that the foot doesn’t move anymore when your moving the pelvis.
This was just a short tip video, and be sure I’ll cover this in my further course.
Cheers,
Pierrick
Please see this: https://imgur.com/fSi3bzE and my answer to 3DSAM.
Hi John, you are right and I’m recording the fixing tutorial.
It will be available soon.
Thanks, hopefully not many people will do this and will follow the updated Soft IK setup. Cheers and sorry for the rant.
Hi John, please ckeck the video and let me know if you think it’s now relevent.
https://youtu.be/gLa9vJgC2tU
Yes this works much better, the shin bone stretching is not that noticeable and the IK does what it is supposed to do. This is a rightful Pro Tip and does no longer lift me up from the chair:) It is even a rig I could live with.
There are couple of ways how Soft IK workaround could be realized, this one sacrifices shin bone non-stretcheability. But this time it doesn’t break the rig, so thumbs up.
I think you explained it well in the video.