Blender | Rigging Practice Part 1: Leg

Blender

2026.8.20

This is a memo of me practicing rigging using a lizard creature model I made for modeling practice.

Terminology

IK

IK stands for Inverse Kinematics.
It’s a technique for efficiently posing 3D characters — by moving the end bone, the other linked bones move automatically along with it.

In simple terms, it’s “a mechanism for automatically adjusting a character’s pose in broad strokes.”

FK

FK stands for Forward Kinematics.
It’s the opposite of IK — by moving the root bone, the other linked bones move automatically along with it.

Pole

This refers to a specific bone that affects IK control.

In simple terms, its role is “to fine-tune the pose that IK has already adjusted.”

Rigging

1｜Setting Up the Leg Bones

Let’s bend it slightly beforehand so that when IK is set up, it automatically recognizes the correct bending direction.

2｜Create the Controller Bones

This time, we’ll set things up so the bone can be controlled from the knee.
To do that, create the bones shown selected in the attached image below.

First, in Edit Mode, extrude bones from the knee bone in the Y-axis direction using shift + e.
Then use command + p to clear the parent relationship.
Since the Pole won’t apply its effect correctly if it’s too close, leave some distance.

Front bone: Pole
Back bone: IK

Use F2 to set the name of each bone.
To make them easy to find later, name them POLE.Leg and IK.Leg.

Next, switch to Pose Mode.
Select the knee and add IK from Bone Constraints.

Select the armature you’re currently using as the target, and choose the Pole and IK bones you just named for their respective slots.

Then change Chain Length to the number of bones you want to link.
Since it’s 3 bones including the one being set this time, change it from 0 to 3.

また、Poleを割り当てるとボーンの回転がずれてしまうため修正します。
※ だいたい45度ベースでズレていると思います。

3｜Check the Movement

If you actually move the IK bone around with g, you can confirm that it’s linked correctly.
Also, moving the Pole bone left and right changes the direction of the knee, confirming that it can be adjusted.

4｜Link the Toe Rotation with IK

Right now it rotates automatically in sync with the knee bone.
For better compatibility with other setups, let’s link it to the IK’s rotation instead.

First, disable Inherit Rotation for the toe bone.

Next, set up the rotation.
Add Copy Rotation from Bone Constraints.

Set the target to the armature and the bone to the IK bone.
Also change the rotation calculation base from World Space to Local Space.

Now you can control the toe in sync with IK.
Try actually rotating the IK bone.
If any axis is rotating in reverse, enable that axis under Invert in the settings above.
※ I enabled Y and Z.

Currently only the toe reflects the rotation, so let’s adjust it so the rotation applies to the whole leg.

Switch to Edit Mode and set the Pole bone’s parent to the IK bone.
While holding shift, select Pole → IK, then build the parent relationship with command + p.
To confirm it applied correctly, check the Relation > Parent value under Bone for the Pole bone — if it shows the IK bone, you’re good.

ポーズモードに移行してIK用ボーンを回転させると足全体が連動して回転するようになりました。