Limb Animation ControlsLimb Animation ControlsCAT's IK SystemManipulating the RigRetargetingStarting a New Animation

Limb controls are found on the Limb Animation rollout, which is available in both Setup and Animation modes.

Moving the IK Target Up the Limb

Traditionally the IK target sits at the end of the limb, but sometimes a different location is necessary. For example, for a crawling character, the IK target should be positioned at the knee. You can animate the IK target up and down the limb with the Num IK Bones setting.

Num IK Bones allows you to slide the IK target up and down the limb. The Num IK Bones value ranges from 0.0 to the number of bones on the limb, including the palm. For example, with a typical leg setup of two leg bones and an ankle, the range goes from 0.0 to 3.0.

Lowering the Num IK Bones value moves the IK target (for example, the Footplatform) up the limb, bone by bone. On a typical leg, the value 1.0 places the IK target at the knee, while a value of 0.0 places it at the top of the leg: the pelvis.

As the value changes, the limb is pulled down through the IK target. This is normal. The part of the limb that is beyond the IK target is in FK.

Num IK Bones=1.0

At this setting the lower leg can be rotated in FK.

As you decrease the IK/FK value, the limb remains in the same place but is ready to animate in IK.

Interface

The Limb Animation rollout provides access to the IK and FK settings for the limb.

Create IK Target: By default, a rig arm has no IK target. To animate in IK, first use the Create IK Target function. This creates a special point helper that serves as the IK target for the arm.

The IK target for a leg is the FootPlatform.

NoteThe Create IK Target function works only with an active Absolute layer.
Select IK Target: Selects the IK target for the selected palm or ankle without having to search for it in the scene.

NoteMoving the IK target affects the limb only when the IK/FK value (see following in this topic) is less than the maximum 1.0. Also, when the IK target is selected, the function and name of this button switch to Select Limb End.
Move IKTarget to Palm: Centers the IK target at the end of the palm. Use this function when you have been animating in FK mode, leaving the IK target behind, and you want to blend back to IK.
Match IK and FK: Creates a seamless blend between IK and FK modes. Click this button with Auto Key on before you blend to or from IK.
IK/FK: Blends between IK and FK on the limb, with 0.0 being IK and 1.0 being FK.

TipNormally, you would not leave the value between 0.0 and 1.0 while animating. The interim values are intended mainly for blending between IK and FK.
Display FK Limb in IK: When on, and the limb is in IK, displays a ghost/wireframe image of the position the limb would be if using FK. This option is useful when you are animating to see quickly what the FK solution is doing when in IK, in case you are having issues with the IK solver bending in the wrong direction.

As you slide the IK/FK slider to the right, the limb gradually assumes the ghost position.

Left: Limb in IK, with Display FK Limb In IK on

Right: Limb in FK
Num IK Bones: Slides the IK target up and down the limb.

The value ranges from 0.0 to the number of bones on the limb, including the palm. For example, with a typical leg setup of two leg bones and an ankle, the range is 0.0 to 3.0.
Retargeting: This slider blends 3ds Max CAT's retargeting for the selected limb. At 0.0, retargeting is off, and a value of 1.0 means retargeting is fully on.