All language subtitles for 08-09-05 Fixing knee pop

- [Instructor] A very common issue

when animating with a 3D character rig

is what we call knee pop and elbow pop.

I won't try to explain why this happened

but whenever you are
extending the arm or the leg

using inverse kinematic, it can happen

that the knee accelerate
to one full extension.

It creates a visual glitch
that we will need to fix.

The first thing to do is
to select the knee tweaker

and calculate its motion path.

As usual, I'm using my quick
favorite, pressing the Q key.

Once that we see the trajectory
of the knee over time,

it's pretty obvious where this
pop or this break happens.

My technique to fix this is
simply to reposition the knee

using the knee tweaker
along the few frames

where it's currently popping.

What I advise you is not
trying to fix this issue

on one frame only,

but instead try to smooth
the motion path of the knee

over several frames.

Because if you try to fix
it over one frame only,

you may push the controller
into a weird pose

and you will generate a new problem

while trying to fix an existing one.

As you may have understood already,

the method is simply to rebuild
the position of the knee

using the knee tweaker controller.

I first do it from the camera view,

but then don't forget to
turn around your character

and check that the motion path
look clean from every angle.

We do favourise camera
view, but for this exercise,

I'd like our animation to
be clean from any angle.