Using Retarget Profiles

In addition to IK Retargeting your characters during runtime, you can modify Global, Root, and Chain settings dynamically using Retarget Profiles. Retarget Profiles are an additional feature of the Retarget Pose From Mesh Animation Blueprint Node which you can use to change or animate these settings. This can be useful in cases where you need to change or apply different retarget settings at different points throughout an animation.

This document provides instructions on how to set up Retarget Profiles and various ways to modify them.

Prerequisites

• You have set up characters to dynamically retarget at runtime using Retarget Pose From Mesh. Refer to the Runtime IK Retargeting page for instructions on how to do this.

• You are familiar with using Animation Blueprints.

• You are familiar with creating and using Sequencer.

Accessing Retarget Profiles

You can access Retarget Profiles from the Retarget Pose From Mesh node in the target character's Animation Blueprint you created in the Runtime IK Retargeting prerequisite step. Select Retarget Pose From Mesh and locate the Custom Retarget Profile properties in the Details panel.

Static Override

By default, the settings you set up in the assigned IK Retargeter Asset are used by the Retarget Pose From Mesh node. You can statically override those settings by modifying the Custom Retarget Profile properties on the node:

Dynamic Override

If you need to control when retarget settings change, then you must create additional blueprint logic. Due to the arbitrary nature of Blueprints and Animation situations, there are many ways you can create logic to edit a variety of retarget situations.

In this example, Retarget Profiles will be used to adjust the larger character's arm to correctly reach for the ground, matching the Mannequin.

IK Rig Setup

Because of this specific retarget situation, you need to modify the target character's IK Rig to use IK Goals and Solvers. This example uses a Full Body IK (FBIK) solver, however depending on your character, you could choose other kinds of IK Rig Solvers. This step is required to provide IK arm Chain Settings for the Retarget Profile to modify.

Open the target character's IK Rig Asset used for retargeting and do the following:

1. Right-click one of the hand bones in the Hierarchy panel and select New IK Goal.

2. In the next prompt, ensure Full Body IK is set as the solver and click Add Solver.

3. Select the Full Body IK solver in the Solver Stack panel, then right-click the other hand bone and select New IK Goal.

4. Lastly, select the Full Body IK solver, right-click the root bone (typically the pelvis or hips) in the hierarchy and select Set Root Bone on Selected Solver.

FBIK Settings

Select Full Body IK in the Solver Stack and set Root Behavior to Pin to Input in the Details panel. This is required to prevent the lower body from moving when the IK goals move.

You may also need to create additional bone settings for bones that are controlled by the FBIK solver. This resolves stiffness or incorrect joint rotation that can result from the FBIK solve. To create a bone setting, select the Full Body IK Solver, then right-click a bone you want to create settings for and select Add Settings to Selected Bone.

In this example, to resolve rotational stiffness for the spine, shoulder, and arm bones, bone settings were created for these bones (including any symmetrical bones) with the following properties:

• Spine_01

  • Rotation and Position Stiffness: 0.75

• Spine_02

  • Rotation and Position Stiffness: 0.75

• Spine_03

  • Rotation and Position Stiffness: 0.75

• Clavicle_l

  • Rotation and Position Stiffness: 0.8

• Lowerarm_l

  • Use Preferred Angles: Enabled

  • Preferred Angles: 0, 0, 45

Retarget Profile Variable Setup

Returning to the target Animation Blueprint, select the Retarget Pose From Mesh node. In the Details panel click the Custom Retarget Profile dropdown menu and enable Expose As Pin, which adds a Custom Retarget Profile pin on the node.

Right-click the newly created pin and select Promote to Variable. This creates a new Struct Variable of type Retarget Profile and connects to the pin. The variable is also visible in the My Blueprint panel.

Create Event Graph Logic

Open the Animation Blueprint Event Graph and reference the Retarget Profile variable here, then do the following:

1. Drag off it and create a Get Chain Settings from Retarget Profile node.

2. Set Target Chain Name to the retarget chain that you want to animate. In this example it is LeftArm.

3. Right-click Return Value and select Split Struct Pin.

Next, drag off Return Value IK and create a Set members in TargetChainIKSettings node. Select it, and enable Static Offset in the Details panel, which exposes the Static Offset chain property as a pin on the node.

Drag off Struct Out and create a Set Chain IKSettings in Retarget Profile node, then do the following:

1. Set Target Chain Name to the same chain name used earlier: LeftArm,

2. Connect the Retarget Profile variable to the Retarget Profile input.

Connect Event Blueprint Update Animation to this execution chain, and expose Static Offset as a variable by right-clicking the pin and selecting Promote to Variable.

Finally, in the Details panel for the Static Offset variable, enable Expose to Cinematics and Instance Editable, which makes the variable editable externally.

Animate Retarget Setting

Because you created logic in the Target's Animation Blueprint Event Graph and linked it to Event Blueprint Update Animation, you can animate the exposed variable in Sequencer the same way you would animate Anim Instances.

Assuming you have already created and opened a Level Sequence, add the retargeted character blueprint to it and the source Skeletal Mesh Component, then play an animation on the source component to observe the retargeting effects on the target.

Next, add the Chain Setting variable you exposed earlier by doing the following:

1. Add the target Skeletal Mesh Component by clicking Add Track (+) on the Blueprint Track and select the Target component.

2. Click Add Track (+) on the target Component Track and select Anim Instance.

3. Select Add Track (+) on the Anim Instance Track and select the variable.

You can now keyframe this track to adjust the chain property in real-time.

Animating Retarget Profiles in conjunction with Runtime Retargeting provides you with a way to make fine-tuning adjustments to your runtime retargeting results without creating new animations or additional assets.