Use the Live Link Hub to stream OptiTrack camera data to the UEFN plugin for video game development in Fortnite.
The OptiTrack Live Link Hub plugin allows game designers to use OptiTrack Motion Capture data to animate characters in Fortnite through Unreal Editor for Fortnite (UEFN).
Download the latest Unreal Engine 5 Plugin from the OptiTrack Downloads page.
Open the Epic Games Launcher. The following Epic Games applications must be installed:
Unreal Engine 5.5
Live Link Hub
UEFN
Fortnite
Launch Unreal Editor for Fortnite (UEFN).
Select Live Link Hub from the Tools menu, if it's not already open.
Click the Settings button in the upper right corner and select Plugins...
In the User Plugin Directories section, click the Add Element button.
Click the ellipses button to browse to and select the downloaded plugin.
Restart UEFN when prompted after the plugin is installed.
In the NatNet section, select Enable to begin streaming.
Select the Local Interface. Use Loopback if streaming to the same computer, otherwise select the IP address for the network where the client application resides.
Set the Bone Naming Convention to UnrealEngine.
Set the Up Axis to Y-Axis. The plugin will bring the data in with a Y-Forward orientation.
Please see the Data Streaming page for more details on all settings available for streaming.
In Unreal Engine, open Live Link Hub from the Tools menu on the toolbar, if it's not open already. Under Virtual Production, select Live Link Hub.
Select OptiTrack Source, check Connect Automatically, or enter the IP address for the Motive PC in the Server Address field, the IP address for the Unreal PC in the Client Address field. Enter 127.0.0.1 in both fields if running both on the same PC. Click create.
Properties are shown in the Source Details tab when the OptiTrack source is selected. The properties that are applicable to Fortnite characters are listed below.
Adjust the location, orientation, or scale of the streaming data.
Timecode is fully supported in the plugin. Click the button in the top right to use preset system time codes or add a new Timecode Provider in the Source Details tab.
Timecode data may appear to stutter in Unreal Editor even when it is transmitting correctly. To confirm that the data is in sync, compare the timecode in Live Link Hub to the timecode in Motive.
Unreal Editor for Fortnite does not support the display of markers.
We recommend using Windows Explorer to copy assets into the project folder. Right-click the project folder in the Unreal Editor Content Browser and select Show in Explorer.
In the Content Browser, copy the following files and folders from All > Engine > Plugins > OptiTrack - Live Link Content > Animations to the project folder:
Female Avatar (folder)
Male Avatar (folder)
Textures (folder)
IK_MotiveAvatar_Opti.uasset (file)
SK_MotiveAvatar_Opti.uasset (file)
The T-Pose asset and animation blueprints typically used in Unreal Engine are not supported in Unreal Editor.
Unreal Editor will validate the project files before launching the live session.
All skeletons in Unreal Editor are based on the standard Fortnite mannequin. Animation is applied to the mannequin rather than using an animation blueprint. In this example, we will use the Fortnite Mannequin to build an IK Rig to receive data from the OptiTrack skeletons.
Before creating our IK Rig, drag the Motive Avatar of your choosing into the scene to prep the retarget phase.
To create the IK Rig:
Right-click in the Content area. Select Animation > Retargeting > IKRig.
Name the IKRig. We recommend IK_FNMannequin.
Double-click the newly created IKRig to edit it. This will open in a new window.
In the Details tab, change the Preview Mesh to the FN Mannequin.
The mannequin is pre-configured to work with Fortnite. This allows you to use the Auto Create features in the upper left corner to finish setting up the IK Rig.
Click the Auto Create Retarget Chains button.
Click Auto Create IK.
Click Reset.
Click Save.
The IK Rig is now configured and the tab can be closed.
Right-click in the Content area. Select Animation > Retargeting > IK Retargeter.
Name the IK Retargeter. We recommend RTG_Motive_FN.
Open the newly created Retargeter.
On the Details tab, go to Source > Source IKRig Asset.
Use the dropdown list to select the standard Motive avatar, IK_MotiveAvatar_Opti.
In the Target section, set the Target IKRig Asset to the IKRig created earlier, IK_FNMannequin.
The Viewport will show that the two skeletons are not properly aligned. This occurs because the skeletons are in different poses.
Click the Running Retargeter button in the upper left corner to stop the retargeter and switch to edit mode. The button will update to Editing Retarget Pose.
Set the Retargeter back to Run mode for the remaining steps.
To complete the next step, it's easiest if only the mapped bone chains are visible.
In the Chain Mapping pane, click the Settings button and select Hide Chains Without IK.
Select all of the mapped Chains.
In the Details tab, go to IK > Blend to Source.
Set the value to 1.0.
Go to Blend to Source > Blend to Source and set the value to 1.0.
The retarget will now display correctly in the Viewport. This window can now be closed.
From the Content Browser, drag the skeletal mesh for the Fortnite mannequin into the scene. The mannequin is located in All > Fortnite > Characters > PlayerBasics.
Both the Motive Avatar and the Fortnite Mannequin will be in the scene.
Select the Motive Avatar.
In the Details tab, go to Performer > Performance Capture > Subject Name.
Select a performer from the list of actors in Motive.
The Motive Avatar will now animate with the selected actor.
Select the Fortnite Mannequin to display its properties in the Details pane.
Once the Retarget Component is attached to the Mannequin, update the following properties in the Retarget section:
Source Skeletal Mesh Component: Select the Motive Avatar.
Controlled Skeletal Mesh Component: This should already be set to the Fortnite Mannequin.
Retarget Asset: Select the IK Retargeter created in an earlier step (RTG_Motive_FN in our example).
The Avatar and Mannequin will animate in realtime only in the Editor, not in the game.
In the Outliner pane, drag the Mannequin to nest under the Motive Avatar.
In the Details pane for the Mannequin, go to Transform > Location and reset the values to 0.
The Avatar and the Mannequin will be aligned.
Once all of the characters are configured, the next step is to record the animation using the Take Recorder and Sequencer in Unreal Editor.
To open either pane, go to the Windows menu > Cinematics.
Type the project name in the Slate field.
Select From Actor > Add 'Device Mannequin'.
With the Mannequin selected, update the following properties:
Disable Transform > Transform Track.
Disable Animation Recorder > Remove Root Animation (shown below).
Go to User Settings > Countdown to include a countdown timer to start recording.
To begin recording, click the large red Play button on the right edge of the Slate in the Take Recorder:
When the recording is completed, click the Review button in the Take Recorder pane.
The character will now animate as expected.
You can find the Take and the associated animations in the Cinematics folder in the Content Browser. Takes are organized with a folder for each subscene. The animations recorded in that subscene are stored in an Animation folder, one for the Device Mannequin and one for the Motive Avatar.
Now that the animation has been created and aligned to the Device Mannequin, it's time to apply it to a Fortnite character. Since all characters in Fortnite use this same skeleton, no additional alignment is required.
Fortnite has a large selection of characters available, all based on the Device Mannequin skeleton. To add a character to the scene from the Content Browser:
Go to Fortnite > Devices > AI.
Drag the Character Device to the scene.
Select the Character Device in the Viewport.
Go to Fortnite > Characters and select the desired character from the gallery.
In the Details pane for the newly added Character Device, drag the Fortnite character you wish to use to User Options > Character.
Select the Fortnite character in the Viewport.
Under User Options, check the box for Custom Idle.
Drag the Device Mannequin animation from the Content Browser to the Custom Idle field.
Fortnite will update the game in Edit Mode, with the status displayed in the upper right corner. The game will move through the following phases: Preparing; Loading Project; Downloading; and Connecting (displayed on the Edit Session screen). When the game loads, the status will be Up to Date.
The animation will play on the Fortnite character when the game starts. It will not play in the editor. To see this, you can start the game from UEFN or inside Fortnite itself.
Setup guide to stream video cameras from Motive using the Camera Role in Unreal Engine.
Motive’s Live Link plug-in for Unreal Engine includes the ability to stream tracked rigid bodies for Virtual Production and InCamera VFX (ICVFX).
Motive tracks video cameras using a CinePuck, an active device equipped with an IMU. The CinePuck mounts directly to the video camera and, when aligned with the camera lens as a Rigid Body, tracks the camera's focal point so it can be replicated virtually in the Unreal Engine environment.
The Camera Role in Unreal Engine can now be used for the Tracked Camera Rigid Body. This means that you can now connect a lens file with the associated Live Link Camera Role Asset. In Unreal Engine, users can calibrate for lens distortion and nodal offset, and use the camera with a Lens Encoder, if desired.
This document provides instructions to setup and link a Rigid Body in Motive to a Live Link Camera Role in Unreal Engine. For information on ICVFX production in general, please see the page .
We used the standard InCameraVFX template in Unreal Engine for our sample project. The template includes all the necessary macros and assets needed for virtual production.
This template is located under Film / Video & Live Events in the Unreal Project Browser.
Motive will stream the camera as a Live Link Rigid Body asset.
Plug the into one of the Power over Ethernet (PoE) switches on the OptiTrack camera network.
Firmly attach the to the Studio Camera using the SmallRig NATO Rail and Clamps on the cage of the camera.
The CinePuck can be mounted anywhere on the camera. For best results, put the puck closer to the lens.
Power on the CinePuck, and let it calibrate the IMU bias. The lights will flash red and orange during calibration and change to green when done.
We recommend powering the CinePuck with a USB cable while filming to avoid running out of battery power. A light on the CinePuck will indicate when the power is connected.
Select OptiTrack Source, check Connect Automatically, enter the IP address for the Motive PC in the Server Address field, the IP address for the Unreal PC in the Client Address field, and click Create. Enter 127.0.0.1 in both fields if running both on the same PC. Leave the Connection Type as Multicast and click create.
This will display a list of assets streaming from Motive. Note that the rigid body camera, named HandCam2, is currently in the Transform role.
Click OptiTrack in the Subject list to display the OptiTrack Live Link Properties.
In the Live Link Roles section, click the Live Link Subject dropdown. This will open the list of Assets streaming from Motive.
Select the camera asset, HandCam2 in this example.
Directly below the Live Link Subject field is a check box to Stream as Camera (Rigid Bodies Only). Check this box to apply the Camera Role to the camera rigid body (HandCam2).
Move all the NDisplay assets to nest under OptitrackLiveLinkDisplay in the Outliner pane.
Select the video camera, now nested under OptitrackLiveLinkDisplay in the Outliner pane..
Search for and select the Live Link Controller component.
Properties for the new Controller will display in the Camera details pane.
Click the dropdown next to Subject Representation and select the camera Rigid Body.
The Subject and Role fields will both update to display the name of the Rigid Body name.
The LiveLinkController label can only be applied to Rigid Body assets.
As noted above, Unreal Engine includes properties that allow you to calibrate a video camera streaming into Unreal Engine. This includes the ability to use a lens encoder with the camera.
When using a Lens Encoder or a calibrated Lens in Unreal Engine, use the Lens File Picker settings to select the appropriate Lens File.
To enable streaming in Motive, click the button to open the Applications Settings panel, then select the Streaming tab, or use the button in the right corner of the Control Deck to open the Streaming tab directly.
Click the button in Live Link Hub to add a new Live Link source.
Once the required assets are copied to the project folder, click the button. Unreal Editor will prompt to Save Selected, with all unsaved content selected by default.
Click the Auto Align button and select Align all Bones to complete the alignment.
Click the Root Settings button in the top right corner.
Click the Add button to add the Performer component.
Click the Add button and use the search bar to find and add the Retarget Component.
Click the Push Changes button to save the change into the Fortnite game.
With the Mannequin selected, click the add source button.
Recorded tracks will show in the Sequencer tab. Click the Stop Recording button when done recording.
Click the Push Changes button to save and update the game.
A CinePuck is tracked in Motive as a Rigid Body asset. For detailed instructions on creating a , Please see the page. For instructions on pairing the IMU, please see the page.
In Unreal Engine, click the button on the Live Link tab to add a new Live Link source.
Click the Quick Add button and start typing OptiTrack over the menu to activate the search function. Select the OptiTrack Live Link Display from the list of available options.
In the Details pane, click the Add button to add a new component to the camera.
Please see for more information on calibrating cameras and working with lens files in Unreal Engine.
Learn how to use the Active Puck Static Meshes included in the Live Link Plug-in Content folder.
OptiTrack's plugin for Unreal Engine includes an array of content options. the 5.3 plugin includes the following new content:
ActivePuckMesh
CinePuckMesh
MotiveAvatarMesh
MotiveSkeletalMesh
MotiveSkeleton
This page covers the Active Puck and CinePuck static meshes, using the Active Puck as the example.
The Active Puck Mesh provides a couple of different use cases:
Data validation. Tracking an active puck in the physical volume using the OptiTrack Live Link display provides a point of reference that allows you to validate rotation, placements, and even the scale of your volume.
We used the standard InCameraVFX template in Unreal Engine for our sample project. The template includes all the necessary macros and assets needed for virtual production.
This template is located under Film / Video & Live Events in the Unreal Project Browser.
This section walks the user through adding the puck static mesh to a project and aligning it with the puck streaming from Motive.
Check the boxes for Show Engine Content and Show Plugin Content.
The Content Browser’s Navigation pane will now show the Engine Content, where the Plugins folder resides.
Open the OptiTrack—Live Link Content folder.
Open the ActivePuckMesh folder. If using a CinePuck, open the CinePuckMesh folder .
The Live Link asset automatically aligns with its source in Motive. The Markers settings display a visual map of the marker locations. This map is helpful for confirming the alignment of a static mesh to a streamed asset.
In the Live Link pane, select OptiTrack.
In the Markers section of the OptiTrack Properties pane, set Create Labeled Markers to true.
To open the Live Link pane, select Virtual Production → Live Link from the Window menu.
Right click in the Content Browser to open the menu.
Under Create Basic Asset, select Blueprint Class.
Select Actor as the Parent Class.
Open the newly created Blueprint linked to the puck streaming from Motive.
Double-click the newly created static mesh in the list of components to rename it. In our example, we called it ActivePuck.
Select the static mesh in the Components pane to display its properties in the Details pane.
Click the Static Mesh property (set to None by default) to select the asset to use.
Select SM_ActivePuck_Opti for the Active Puck, or SM_CinePuck_Opti if using a CinePuck.
The Active Puck static mesh will now appear in the scene.
An Active Puck can serve as a lens calibration device in Unreal Engine by aligning calibration points to the markers at each of the four corners.
For accuracy and precision, use the Top view in the UE Viewport.
Search for and select Calibration Point from the list of options.
Click to rename the Calibration point. We recommend using names that match the point's location, such as top left, bottom right, etc.
Drag the newly created point to align it with the center of the corner marker.
Use Ctrl + D to Duplicate the point to make the next one.
Rename the second point and drag it to the appropriate location, aligning it with the previously placed point on either the X or Y axis.
Repeat these last two steps until each of the four corners has a Calibration Point at its center.
Select the ActivePuck in the list of components. The four calibration points should be nested underneath.
Click the Compile button on the main toolbar, then Save and Close the tab for the Blueprint.
In the project, click and drag the Blueprint created in the prior steps into the project.
In the Outliner pane, drag the Blueprint under OptiTrackLiveLinkDisplay.
Under Subject Representation, click and select ActivePuck from the list of available assets (below, left).
This will link the static mesh to the puck. The Labeled Markers setting shows the device properly aligned (below, right).
Use the translate tool to reorient the static mesh if the OptiTrack brand and the status lights on the mesh do not align with those on the physical puck.
The puck is now available as a tracked calibrator tool that can be used in conjunction with a lens file in Unreal Engine for lens calibration.
Right click in the Content Browser in the folder where you'd like to save the lens file.
Search for and select Lens File from the list of Content types and give the file an appropriate name, such as 35mm_Lens.
Open the Lens File.
Click Lens Distortion on the Calibration Steps tab.
In the Lens Distortion Algo setting on the right, select Lens Distortion Points Method.
The Calibrator setting will default to the calibrator puck.
Select the current calibrator point in the camera viewport to complete the alignment.
Lens calibration device. Because the static mesh is the same scale as a real puck, its markers can be used for calibration purposes. Please see the section , below, for more details.
From the Content Browser window, click the button.
Double-click the name to give it a more meaningful name. In our example, we renamed the component BP_CalibratorPuck. We will use this puck later to create a .
This will open a new tab. Click the Add button in the top left of the Component pane and select Static Mesh from the list of options.
Select the Active Puck in the Viewport and click the Add button on the Components tab.
In the Transform Section of the Details pane, click the button to the right of the Location settings to reset all location values to zero.
Click the Add button in the Details pane. Search for and select Live Link Controller.
Having confirmed the alignment is correct, you can turn off the display. The Live Link display settings can also be closed.
Step-by-Step instructions for retargeting Live Link content in Unreal Engine.
Motive 3.1 or higher
Unreal Engine 5.5
OptiTrack Live Link Plugin 5.5
This step is completed once per computer.
Download and unzip the latest version of the OptiTrack Live Link Plugin from the OptiTrack Download site.
Place the plugin files into one of the following directories:
A global engine plugin can be placed in C:\Program Files\Epic Games\ [Engine Version]\ Engine\ Plugins
A project-specific plugin can be placed in [Project Directory]\Plugins
This step is completed with each new project.
Go to Edit → Plugins and enable the two required plugins:
OptiTrack - Live Link plugin, located under the Installed group. This is the plugin downloaded in the previous step.
Unreal Engine's built-in Live Link plugin.
Search for Live Link on the plugins window to find these and other Live Link related plugins.
Allow Unreal Engine to restart, then close the plugin window when the project reloads.
Show Content
To show the OptiTrack plugins folder in the Content Browser, click the Settings button in the Browser's top right corner and check the boxes to Show Engine Content and Show Plugin Content.
In the NatNet section, select Enable to begin streaming.
Select the Local Interface. Use Loopback if streaming to the same computer, otherwise select the IP address for the network where the client application resides.
Set the Bone Naming Convention to UnrealEngine.
Set the Up Axis to Y-Axis. The plugin will bring the data in with a Y-Forward orientation.
Please see the Data Streaming page for more details on all settings available for streaming.
In Unreal Engine, open Live Link Hub from the Tools menu on the toolbar, if it's not open already. Under Virtual Production, select Live Link Hub.
Select OptiTrack Source, check Connect Automatically, or enter the IP address for the Motive PC in the Server Address field, the IP address for the Unreal PC in the Client Address field. Enter 127.0.0.1 in both fields if running both on the same PC. Click create.
Live Link will display information about the connection, including a list of assets streaming from Motive:
The OptiTrack Live Link Display provides validation that the data is streaming in correctly from Motive. In the Unreal Engine Outliner pane, all assets in the Motive volume should nest under the OptiTrack Live Link Display.
Play the Take file when working with recorded data to see the Live Link assets in the Viewport. Once the assets are available, you can pause playback and the assets will still be displayed.
Once you have validated the Live Link connection, we recommend turning off Live Link asset visibility to improve performance as you work through the rest of the pipeline.
Select OptitrackLiveLinkDisplay in the Outliner panel.
The properties for the OptitrackLiveLinkDisplay will populate in the Details pane.
In the Assets section, uncheck Display Assets.
Turn the Display Assets setting on or off as needed throughout the workflow.
Retargeting is the process of applying an existing animation model to a character, at the correct scale.
In this section, we'll demonstrate the retargeting workflow using skeleton data streaming from Motive and retarget it to a MetaHuman in Unreal Engine in real-time. For each MetaHuman, we'll create the following in Unreal Engine:
A Retargeter to map the Motive Animation data to the correct Skeletal Meshes in Unreal.
An Animation Blueprint for the Motive Avatar.
An Animation Blueprint for the MetaHuman.
A Blueprint for a MetaHuman character.
For more information and tutorials about working with MetaHumans in Unreal Engine, please visit Epic Games' MetaHuman community.
This workflow is fine-tuned specifically for MetaHumans, but it can also be used for other characters with unique custom skeletons.
MetaHuman joints use a Y-Forward axis, and the plugin brings the data in using this orientation.
Prior versions of the plugin used an X-Forward axis for the skeletal mesh, with adjustments made to the linked asset in Unreal Engine. To work with legacy assets configured for an X-Forward axis:
From the LiveLink tab, select OptiTrack to display the LiveLink properties.
In the Coordinates section, uncheck Animate Y-Forward.
We'll start the workflow by adding the MetaHuman to the project. This will create a folder structure in the project to consolidate the content related to each individual MetaHuman. We'll use these folders to save the Retargeter and the two Animation Blueprints we need to complete the retarget.
To add a new MetaHuman to your project:
Select either a new MetaHuman from a preset to download or browse the local collection for any previously downloaded MetaHumans.
Once the MetaHuman is downloaded, a green arrow will appear in the upper left corner of the profile picture. Click the blue arrow in the upper right corner to add the MetaHuman to your project.
The DNA Import Options window will open. Select the appropriate Skeletal Mesh for the new MetaHuman. All OptiTrack skeletal meshes end with _Opti, making them easily searchable. Gender-specific meshes include an "F" or an "M" in the name. Legacy meshes using an X-Forward axis include "Xforward."
The Content Browser will have a new MetaHumans folder within the Content folder. Each MetaHuman has their own folder, which contains their Blueprint and all the content needed to render them.
We recommend using a copy of the MetaHuman when setting up the retarget. This allows you to take the data that comes from the MetaHuman in the retarget during production and add it to the original MetaHuman later in post-production.
To create a copy, right-click the Blueprint and select Duplicate, or use the keyboard shortcut Ctrl + D.
We suggest using a simple convention such as BP_<MetaHumanName>_Retarget for all copies.
Now that the file structure for the MetaHumans is setup, we can create the Retargeter and the two Animation Blueprints. We'll update the MetaHuman Blueprint once these are done.
In the Content Browser, browse to and open the folder for the MetaHuman.
Right-click the Content Browser and select Animation -> Retargeting -> IK retargeter.
Name the retargeter. We recommend a name such as IKR_Motive_to_Meta.
Open the newly created retargeter. In the Details pane, update the Source and Target values as follows:
Source IKRig Asset: IK_MotiveAvatar_Opti
Source Preview Mesh:
Female avatars: SKM_F_MotiveAvatar_Opti
Male avatars: SKM_M_MotiveAvatar_Opti
Target IKRig Asset: IK_metahuman
Target Preview Mesh:
Female avatars: f_med_nrw_body
Male avatars: m_med_nrw_body
The Preview Mesh fields will auto-complete once the IKRig Asset is selected.
The Viewport will show that the two skeletons are not properly aligned. This occurs because the skeletons are in different poses.
Click the Running Retargeter button in the upper left corner to stop the retargeter and switch to edit mode. The button will update to Editing Retarget Pose.
The retarget will now display correctly in the Viewport.
Right-click the Content Browser and select Animation -> Animation Blueprint.
In the Create Animation Blueprint Search bar, type Opti, then select the SK_MotiveAvatar_Opti skeleton. Give the newly created Animation Blueprint a name, such as ABP_MotiveAvatar.
Double-click the new Animation Blueprint to open the AnimGraph window.
Right-click in the graph area and type Live Link Pose in the Search field, then select the node that appears.
In the Live Link Pose node, use the dropdown list under Live Link Subject Name to select the actor whose skeleton will be used for the Motive avatar.
To connect the two nodes, click the Result icon in the Output Pose and drag it to the corresponding icon on the Live Link Pose.
Click the Compile button, then Save. The Compile button will update as all changes are incorporated:
Right-click the Content Browser and select Animation -> Animation Blueprint.
On the Create Animation Blueprint window, select the metahuman_base_skel skeleton.
We suggest a naming convention such as ABP_<MetaHumanName>_Meta. Name, then open the newly created animation blueprint.
Right click the AnimGraph. From the list of All Actions, search for and select Retarget Pose From Mesh.
Select Retarget Pose from Mesh in the AnimGraph to display its properties in the Details pane.
Find IKRetargeter Asset in the Settings section.
Drag the Output Pose Result icon to the corresponding icon on the Retarget Pose From Mesh node to link the two.
Click the Compile button, then save.
Open the MetaHuman Blueprint created in a prior step.
Click the Viewport tab to see the MetaHuman character.
Name the new mesh something distinct, such as OptiTrackSkeletalMesh.
Drag the body component of the MetaHuman under the new skeletal mesh.
The Components should now look like this:
Next, add the Live Link Skeletal Animation component. This will allow playback to start once the animation blueprint is attached.
To improve performance while streaming to MetaHumans, click the LODSync component. In the Details pane, go to LOD -> Forced LOD and change the setting to 1.
Click Compile to update the Blueprint, then save.
In the Components pane, select the OptiTrack skeletal mesh created previously.
In the Details pane, go to Animation -> Anim Class.
Use the drop-down to search for and select the Motive Avatar Animation Blueprint created earlier.
With the OptiTrack skeletal mesh still selected, go to Mesh -> Skeletal Mesh Asset.
Type Opti in the dropdown's search bar to quickly find the applicable Motive Avatar. This should match the the Source Preview Mesh used in the IK Retargeter created earlier:
Female avatar: SKM_F_MotiveAvatar_Opti
Male avatar: SKM_M_MotiveAvatar_Opti
In the Components pane, select the skeletal mesh for the MetaHuman. This is the Body previously moved to nest directly below the OptiTrack Skeletal mesh.
In the Details pane, go to Animation -> Anim Class.
Use the drop-down to search for and select the MetaHuman Animation Blueprint created earlier.
With the MetaHuman (body) skeletal mesh still selected, go to Mesh -> Skeletal Mesh Asset.
Select the same mesh used in the Target Preview Mesh in the IK Retargeter created earlier:
Female avatar: f_med_nrw_body
Male avatar: m_med_nrw_body
Animation should now be playing in the viewport of the MetaHuman blueprint.
Disregard any visual issues with the animation in this view. They will not appear in the environment when you add the MetaHuman to your scene.
Now that the MetaHuman blueprint is configured correctly, drag it from the Content Browser into the scene.
In the Outliner pane, drag the newly added blueprint to the OptiTrackLiveLinkDisplay component created earlier. The mouse tip will display the drop location with a green checkmark as you drag the component, to show exactly where it will nest when the mouse is released.
Once the MetaHuman is nested under the OptiTrackLiveLinkDisplay, its location coordinates will update to reflect the OptiTrack global origin.
If you previously disabled the display of assets after setting up the OptiTrack Live Link Display, re-enable the display now to validate that the retarget is running correctly.
The MetaHuman may not be animating exactly as intended. At this point, the rest of retargeting is much more of a trial-by-error artistic process.
We achieved the best standard results using the following settings for all the Hand and Foot Goals, however, we recommend testing other values and changing other fields to get the best results for your project:
FK
Rotation Mode: One to One
Translation Mode: Absolute
IK
Blend to Source: 1
Prior versions of the plugin used an X-Forward axis for the skeletal mesh, with adjustments made to the linked asset in Unreal Engine. To work with legacy assets configured for an X-Forward axis, uncheck the box ...
This page provides instructions on how to use the OptiTrack Unreal Engine Live Link plugin. The plugin communicates with Unreal's built-in Live Link system by providing a Live Link source for receiving tracking data streamed from Motive. This plugin can be used for controlling cameras and objects in virtual production applications. When needed, the OptiTrack Unreal Engine Plugin can also be alongside this plugin. For a specific guide to InCamera VFX (i.e. LED Wall Virtual Production) please see this wiki page Unreal Engine: OptiTrack InCamera VFX.
1. [Motive] Setup Rigid Body streaming in Motive.
Get Motive streaming with at least one Rigid Body or Skeleton asset. Make sure the Streaming settings are configured correctly, and the asset is active under the Assets pane.
2. [UE] Install the OptiTrack plugins in Unreal Engine (UE).
You can install the OptiTrack Unreal Engine plugin by putting the plugin files into one of the following directories:
A global engine plugin can be placed in C:\Program Files\Epic Games\ [Engine Version]\ Engine\ Plugins\ Marketplace
A project-specific plugin can be placed in [Project Directory]\Plugins
3. [UE] Enable the plugins in UE project.
Go to Edit → Plugins and enable two of the required plugins. First one is the OptiTrack - Live Link plugin under Installed group, and the second one is the built-in Live Link plugin under Built-In group.
4. [UE] Open the LiveLink pane
Open the LiveLink pane from Window → Virtual Production → Live Link in the toolbar.
5. [UE] Configure and create a new OptiTrack source
In the LiveLink pane under Source options, go to the OptiTrack Source menu and configure the proper connection settings and click Create. Please make sure to use matching network settings configured from the Streaming pane in Motive.
6. [UE] Check the Connection.
If the streaming settings are correct and the connection to Motive server is successful, then the plugin will list out all of the detected assets. They should have green dots next to them indicating that the corresponding asset has been created and is receiving data. If the dots are yellow, then it means that the client has stopped receiving data. In this case, check if Motive is still tracking or if there is a connection error.
1. Add the camera object or static mesh object that you wish to move
Add a camera actor from the Place Actors pane or a static mesh from the project into your scene. For the static meshes, make sure their Mobility setting is set to Movable under the Transform properties.
2. Add a LiveLinkController Component
Select an actor you want to animate. In the Details tab select your "actor" (Instance). In the search bar, type in Live Link. Then click on the Live Link Controller from the populated list.
3. Select the target Rigid Body
Under the Live Link properties in the Details tab click in the Subject Representation box and select the target Rigid Body.
4. Check
Once the target Rigid Body is selected, each object with the Live Link Controller component attached and configured will be animated in the scene.
When the camera system is synchronized to another master sync device and a timecode signal is feeding into eSync 2, then the received timecode can be used in UE project through the plugin.
1. Set Timecode Provider under project settings
From Edit → Project Settings, search timecode and under Engine - General settings, you should find settings for the timecode. Here, set the the Timecode Provider to LiveLinkTimeCodeProvider.
2. Set OptiTrack source in the Live Link pane as the Timecode Provider
Open the Live Link pane, and select the OptiTrack subject that we created when first setting up the plugin connection. Then, under its properties, check the Timecode Provider box.
3. Check
The timecode from Motive should now be seen in the Take Recorder pane. Take Recorder pane can be found under Window → Cinematics → Take Recorder in the toolbar.
1. Create a new Animation Blueprint
Right click the mesh you would like to use and select "Create > Anim Blueprint"
2. Name and Open the Animation Blueprint
Name the animation blueprint something appropriate, then double click it to open the blueprint.
3. Hook up your Blueprint
Create a "Live Link Pose" component and connect it to the "Output Pose". Assign the "Live Link Subject Name" to the Skeleton that you would like to use.
Change the "Retarget Asset" property in the Details pane of the blueprint editor to "OptiTrackLiveLinkRetarget"
4. Getting the Skeleton to Animate
To animate the Skeleton in real time click the Animation Blueprint from earlier. In the Details pane under the skelteonLive Link Skeleton Animation". After you add that component the mesh should start animating.
To animate the Skeleton in a game, just press the play button. Adding the "Live Link Skeleton Animation" object is not necessary to animate in play mode.
5. OptiTrack Live Link Display
In order to see the debug skeleton overlay from Motive, you can enable the OptiTrack Live Link Display. From the Quick Add dropdown from the toolbar, you can select OptiTrack Live Link Display. This will appear in the Outliner tab and you can change any settings in its Details tab as needed.
Debugging Note
If the retargeting doesn't match the mesh correctly, then you can create a new OptiTrackLiveLinkRetarget blueprint from scratch and modify the bone mapping names.
Animating a MetaHuman follows basically the same steps as another Skeleton, but requires hooking into the Skeleton at a very specific location. For more information about MetaHuman setup outside of our scope, please visit Epic Games's website.
First, you'll want to verify that the Quixel Bridge plugin is installed with Unreal Engine 5. You can install the Quixel Bridge plugin from the Epic Games Launcher by clicking Unreal Engine then the Library Tab.
You'll also wan to make sure that the Quixel Bridge plugin is enabled. To do this go to Edit > Plugins > Editor and click the check box. You may have to restart Unreal after enabling this plugin.
Navigate to the Cube + icon in the top toolbar, select the dropdown and choose Quixel Bridge.
From here, log into your account and select the MetaHuman you want to download/ add to your project.
In your newly created MetaHuman folder (Note: The folder will be labeled whatever your MetaHuman name is), in the Content Browser, create an animation blueprint by right clicking and navigating to Animation> Animation Blueprint.
For the skeleton asset, simply choose the metahuman_base_skel. There is no need to choose anything different for the parent class, keep it as AnimInstance.
Click Create and name it, “ABP_ Metahuman Name”
Each MetaHuman will have a “Body” mesh attached to the MetaHuman blueprint. This mesh will have a post-processing animation blueprint automatically attached to it when you import it into your project. We want to remove this from the mesh because it can cause crashing errors if they are used improperly.
Now in the mesh, scroll down to the Skeletal Mesh section and clear the “Post Process Anim Blueprint”.
With this done, you can now use multiple MetaHumans in your project while all of them are using the same skeleton.
Removing this Post Process Anim Blueprint disabled any way of the mesh itself receiving animations.
Now we will drive all the animation in the animation blueprint we made earlier.
You can also simply choose the animation blueprint that you made as well. It may cause multiple calls to the blueprint and in multiple areas, so be cautious.
Open the animation blueprint that we made in step 2.
You should now see the Animation Graph, if you don’t, navigate to the left in the Animation Graphs and click on “AnimGraph”. In the AnimGraph, right click and type “Live Link Pose”.
Now attach it to the OutPut Pose node.
You can add an input pose if you’d like to keep your blueprint free of any compile notes or errors.
While you have the “Live Link Pose” node selected, navigate to the Details panel and under retarget, select Retarget Asset > OptiTrackLiveLink.
Now to choose an actor.
Make sure you have added a live link source streaming over from Motive.
Choose an actor for the selected dropdown.
You can select a different actor per AnimBlueprint, as long as you have the proper Post Process Blueprint Animation settings. Referenced in step 3.
Click Compile and Save.
Next, navigate to your MetaHuman blueprint and open it.
In the “Components” section on the left, scroll down and select LODSync.
Now on the right go to LOD > Forced LOD and choose any LOD that works for your use-case.
Do not use –1 as the Forced LOD as this will crash Unreal.
Go back to the Components panel and click on Body.
On the right in the Details panel, go to Animation> Animation Mode> Use Animation Blueprint.
In the Anim Class choose the MetaHuman AnimBP that you created earlier.
Lastly in the Components panel, click the '+ Add' button and type in ”Live Link Skeletal Animation” and then click Compile.
If you go to your main Map, you can click and drag your MetaHuman in the scene to watch them animate in Realtime.
For testing the project in standalone game mode, or when developing an nDislay application, the Live Link plugin settings must be saved out and selected as the default preset to be loaded onto the project. If this is not done, the configured settings may not get applied. After configuring the LiveLink plugin settings, save out the preset from the Live Link pane first. Then, open the Project Settings and find Live Link section in the sidebar. Here, you can select the default Live Link preset to load onto the project, as shown in the screenshot below. Once the preset is properly saved and loaded, the corresponding plugin settings will be applied to the standalone game mode.
If all the configuration is correct, the actors will get animated in the newly opened game window when playing the project in the standalone game mode.
Another path to get data into Unreal Engine is to stream data from Motive -> MotionBuilder (using the OptiTrack MotionBuilder Plugin) -> Unreal Engine (using the Live Link plugin for MotionBuilder). This has the benefit of using the Human IK (HIK) retargeting system in MotionBuilder, which will scale characters of very different sizes/dimensions better than the base Live Link plugin. More information can be found by consulting Unreal Engine's Live Link to MotionBuilder documentation.
To enable streaming in Motive, click the button to open the Applications Settings panel, then select the Streaming tab, or use the button in the right corner of the Control Deck to open the Streaming tab directly.
Click the button in Live Link Hub to add a new Live Link source.
Click the Quick Add button and start typing OptiTrack over the menu to activate the search function. Select the OptiTrack Live Link Display from the list of available options and drop it into the scene in the desired location.
Click the Quick Add button and select Quixel Bridge.
Click the Auto Align button and select Align all Bones to complete the alignment.
Click the button and select the IK retargeter created in the prior step.
In the Components panel, Click the Add button and select Skeletal Mesh.
To align the MetaHuman with the subject configured in the Motive Avatar Animation Blueprint, go to Details -> Transform and zero out the coordinates by clicking the button to the right of the values.
Open your MetaHuman blueprint by double-clicking it. In here, click the Body in the components section, and in the details, panel go to Mesh> Skeletal Mesh, then click to navigate to the mesh in the content browser. Open the mesh by double clicking on it.
