Plugin Overview

The OptiTrack Unreal Engine Plugins allow you to stream real-time tracking data from Motive into Unreal Engine. This includes tracking data of Rigid Bodies, Skeletons, and HMDs that are tracked within Motive. This article focuses on the organization of those plugins. For basic instructions on setting up a motion capture system, please refer to the Getting Started guide instead.

Included Plugins:

• OptiTrack - Live Link

• OptiTrack - Streaming Client

• OptiTrack - VR Latency Optimization

HMD Compatibility

• A variety of head mounted displays (HMDs) can be integrated using the OptiTrack OpenVR Driver.

• For plugin version 1.23 and above, support for Oculus HMDs has been deprecated.

Motive Data Streaming Setup (Server)

First, you'll want to follow the below instructions to set up the data streaming settings in Motive. Once this is configured, Motive will be broadcasting tracking data onto a designated network interface where client applications can receive them.

Streaming Settings

Open the Data Streaming Pane in Motive's Settings window and set the following settings:

• Enable - Turn on the Enable setting at the top of the NatNet section.

• Local Interface - Choose the desired IP network address from this dropdown to stream data over.

  • Loopback

    • This is the local computer IP address (127.0.0.1 or Localhost).

    • Used for streaming data locally on the PC you are running Motive on that does not interact with the LAN.

    • Good option for testing network issues.

  • 192.168.0.1x (typical, but may be different depending on which interface is used to establish a LAN connection)

    • This IP address is the interface of the LAN either by Wi-Fi or Ethernet.

    • This will be the same address the Client application will use to connect to Motive.

• Transmission Type

  • For streaming over a Wi-Fi network, setting the Transmission Type to Unicast is strongly advised.

• Select desired data types to stream under streaming options:

  • Rigid Bodies - Enabled (required).

  • Skeletons - Optional for Skeleton tracking.

  • Markers (Labeled, Unlabled, Asset) - Disabled for HMDs (advised).

  • Devices - Disabled.

• Skeleton Coordinates

  • Set to Local.

• Bone Naming Convention

  • Set the appropriate bone naming convention for the client application. For example, if the character uses the FBX naming convention, this will need to be set to FBX.

Plugins

Unreal Engine 4

OptiTrack - Live Link ver. 2.27

The Unreal Engine: OptiTrack Live Link Plugin is primarily intended for Virtual Production applications that require use of real-time cameras or Skeleton tracking in Unreal Engine. It interfaces with Unreal Engine's built-in Live Link plugin to allow for for streaming data from Motive in both real-time and runtime. When timecode data is available in Motive, streamed timestamps can be used to align the data with other components within the project.

OptiTrack - Streaming Client ver. 2.27

The Unreal Engine: OptiTrack Streaming Client Plugin is primarily used for Virtual Reality due to it's low latency optimizations. It provides streaming of Rigid Body and Skeleton tracking data from Motive into Unreal Engine, and it also includes helper functions and actors to provide quick integrating of the plugin into the scene.

OptiTrack - VR Latency Optimization ver. 2.27

The OptiTrack - VR Latency Optimization plugin is an optional plugin for SteamVR projects. When enabled, it provides HMD render compensation to minimize latency in VR applications. For users developing for SteamVR using the OptiTrack plugin, whether or not using the OptiTrack OpenVR Driver, it's suggested to have this plugin enabled.

Unreal Engine 5

OptiTrack - Streaming Client ver. 3.0

This version of the plugin is compatible with Unreal Engine 5.

OptiTrack - Streaming Client ver. 3.0

This version of the plugin is compatible with Unreal Engine 5.

Integrating HMDs

OptiTrack motion capture systems can be used to track head mounted displays (HMD) and integrate the tracking data into Unreal Engine for VR applications. For instructions on integrating HMD tracking data into Unreal Engine, please refer to the corresponding page:

• Unreal Engine: HMD Setup

Wireless Multiplayer Setup

When setting up multiplayer games on wireless clients, it is more beneficial for each client to make direct connection to both the tracking-server (Motive) and the game-server, rather than rebroadcasting the streamed tracking data through the game-server. Then, any of the game related actions that interacts with the tracking data can be processed on the game-server, and this server can send out the corresponding updates to the wireless clients. This allows the wireless clients to only receive both the tracking data or updates without having to send back any information; in other words, minimizing the number of data transfers needed. If wireless clients are sending data there will be a minimum of two transfers on the wireless network, and each transfer of data through wireless network is at risk of latency or lost packets.

This page provides instructions on how to set up the OptiTrack Streaming Client Unreal Engine plugin. This plugin is intended for Virtual Reality customers, but can be used with many other applications.

Streaming Client Setup (Client)

Next step is to configure the client. Follow below instructions to install and configure the OptiTrack Unreal Engine plugin to receive the streamed tracking data.

Enable the Plugin

OptiTrack - Streaming Client Plugin (required)

1. Download the .

2. Extract the contents from the ZIP file.

3. Open the extracted OptiTrack folder, transfer the entire "OptiTrack" folder into the Unreal Engine's plugin directory located in the C:\Program Files\Epic Games\5.#\Engine\Plugins folder (there will be other plugins in that folder already).

4. Open/Create a new Unreal Engine project.

5. Under the Edit menu, click Plugins to open up the panel where all of the available plugins are listed.

6. Browse to OptiTrack section and enable the "OptiTrack - Streaming Client".

7. Click Apply to submit the changes. It will require the Unreal Engine project to be restarted

Set up the Client Origin

Once the OptiTrack - Streaming Client plugin is enabled, the OptiTrack Client Origin actor will be available in Unreal Engine.

OptiTrack Client Origin

OptiTrack Client Origin

The OptiTrack Client Origin class enables the Unreal Engine (client) to communicate with the Rigid Body, Skeleton, and HMD tracking data streamed from Motive.

To add the client origin, simply drag-and-drop the OptiTrack Client Origin from the Place Actors panel into the level. Once the client origin is placed within the level, its position and orientation will reconcile the global origin of Motive in Unreal Engine. In other words, the tracking data will be represented relative to where this Client Origin object is positioned and oriented.

Connecting Unreal Engine to Motive

2. [Unreal] Once the plugin is added and enabled in the project, the OptiTrack Client Origin class will be available from the Place Actors panel.

3. [Unreal] Drag and drop the OptiTrack Client Origin into the scene.

4. [Unreal] Place the OptiTrack Client Origin at the desired location within the scene.

5. [Unreal] Select the instantiated OptiTrackClientOrigin object from the World Outliner panel.

6. [Unreal] In the Details panel, make sure its Auto Connect setting is checked. This configures the client origin to automatically search the network and connect to Motive.

7. Now that the client origin is set, the client origin will attempt to connect to Motive and start receiving the tracking data whenever the scene is played.

Animate Rigid Bodies

OptiTrack Rigid Body Actor

Set Up Steps

1. [Unreal] From the Place Actors panel, search for OptiTrack Rigid Body Actor, then drag-and-drop the actor into the scene.

2. [Unreal] With this Rigid Body actor selected, attach the target actor that you wish to animate using the Details panel. Make sure the target actor's transformation is set to movable.

3. [Unreal] Set the relative locations and rotations to all zeroes on this target actor. This actor should be listed as a child of the Rigid Body actor.

4. [Motive] In Motive, assign a value to Streaming ID property for the target Rigid Body.

5. [Unreal] In the properties of the OptiTrack Rigid Body Actor component, match the Tracking ID with the Streaming ID of the Rigid Body asset in Motive.

6. Make sure both Motive and OptiTrack Client Origin is set up for streaming, hit Play, and the attached actor object will be animated according to the live-streamed Rigid Body tracking data.

RigidBodyComponent Properties

Tracking ID

Hide on Invalid Definition

When this is checked, the corresponding Rigid Body actor will be hidden from the level until the associated Rigid Body data is streamed out from Motive and received by the plugin.

Disable Low Latency Update

Low latency update feature allows Rigid Body position and orientation transform to be updated immediately before rendering minimizing the latency. This is enabled by default. For debugging, you can check this setting to disable this behavior.

Tracking Origin

This sets a specific client origin to use for receiving tracking data. When this is unset, the plugin will default to the first client origin that it finds in the scene.

Respect Parent Transform

When this is set to true, the Rigid Body transform data from Motive will be applied in respect to the parent actor's pivot coordinates. By default, this is set to false, and all of the tracking data will be applied in respect to the pivot axis of the client origin.

Drawing Markers

When needed, you can also draw labeled marker data from Motive into the scene in UE. In most applications, you do not have to draw the markers as Rigid Body data and the Skeleton data will be used instead; however, getting markers generated in the scene may be helpful for debugging purposes. To enable drawing of the markers:

• [UE4] Expand the OptiTrackClientOrigin (Instance) properties, and enable the Draw Markers checkbox.

Animate Skeletons

Tutorial Video

Setup

Follow the below steps to set up Skeleton streaming onto Unreal Engine.

1. Create a Animation Blueprint in the 3D View

Step 2. Right-click the blank space in the Content Browser pane, then select Animation → Animation Blueprint.

Step 3. On the pop-up window, select the OptiTrackAnimInstance at the parent class section at the top and click on the target Skeleton name at the bottom. Then click OK.

Step 4. In the content browser, assign a name to the created animation blueprint.

Step 5. Drag the character blueprint into the scene.

Step 6. Select the character blueprint in the 3D View

• In the Details Pane, select “+ ADD” and create a new an “OptiTrack Skeleton Instance” on the model.

• Set the “Source Skeleton Asset” equal to the Skeleton name in Motive.

2. Setup the Blueprint

**Step 1.**Double-click the animation blueprint in the content browser to open its editor.

**Step 2.**Right-click the animation graph, then create a new "OptiTrack Skeleton".

**Step 3.**Right-click the animation graph, then create a new "Get Streaming Client Origin" and connect its output to the Streaming Client Origin.

**Step 4.**Right-click the animation graph, then create a new "Get Source Skeleton Asset Name" and connect its output to the Source Skeleton Asset Name.

Step 5. Right-click the animation graph, then create a new "Component To Local" and connect the output from "OptiTrack Skeleton" into its input.

**Step 6.**Connect all of the nodes together. The basic animation flow chart should look like the following.

3. Assign Bone Mapping

Step 1. Select the OptiTrack Skeleton plugin in the blueprint graph area.

Step 2. Drop down the Bone Mappings property in the Details Pane.

Step 3. Click “Auto Fill Bone Mapping” to automatically assign the bones in the Skeleton to the OptiTrack Skeleton names.

Note: There is no standard for bone naming conventions, so bone names may vary depending on characters. After doing the auto-fill, review the list and double-check that the auto-assigned names are correct. You may need to manually use the drop-down menu to adjust the assigned mapping for missing, or incorrect, items.

Step 4. Hit "Compile" in the top left to build the blueprint.

4. Setup OptiTrack Streaming

Step 1. Open the 3D View

Step 2. Search OptiTrack Client Origin in the Modes pane.

Step 3. Drag the OptiTrack Client Origin into the 3D scene, then select it to access its properties.

• (Optional) put it at 0,0,0 location.

• Make sure that streaming settings on both Motive and Unreal match.

5. Click _Play_

Notes on bone mapping

The OptiTrack Unreal Engine Skeleton Plugin uses bone mapping, not retargeting. This means that the bone segments in Motive map directly to the character model (bone mapping), instead of being translated into something that is usable by a more abstract biped model (retargeting). Because of this non-anatomical Skeletons will not map correctly without some additional tweaking.

Practically, this means that you will need to do things like turn off the toe mapping for characters with high heels, adjusting the pelvis bone in Motive or in the model for characters with non-anatomical hip bones, and not use bipeds that are too anatomically different than humans, such as a gorilla or swamp monster.

For example, the character sample below has both a non-anatomical pelvis and high heels. It is preferable to use character models that are more anatomically correct, but in this case, you can do a couple things to mitigate these issues:

1. Turn-off toe streaming

In the example below, since this character is wearing heels, any actor providing data for this model will also need to be wearing heels. To get around this you can just turn off the toe mapping in the OptiTrack Unreal Engine Skeleton Plugin.

2. Adjust the bone segments in Motive

The hip segment on the Countess actor is centered in the stomach rather than in the pelvis, the neck bone in Motive is a bit too long for the model, and the shoulders in Motive do not match the width of the character’s shoulders. By adjusting bones' positions and lengths in Motive, you can make the streamed Skeleton to better match the model; however, please note that there are limitations to how much you can do this.)

Bone Scaling

When streaming Skeleton data to animate characters that have different bone lengths compared to the mocap actor, the UE character will need to be scaled accordingly. In this case, the "Scale Bones" feature in the OptiTrack Skeleton node automatically scales the character bones to match the mocap actor. This setting is enabled by default.

Aligning Bones

The OptiTrack Unreal Engine Skeleton Plugin uses bone mapping, not retargeting. This means that the bone segments in Motive map directly to the character model (bone mapping), instead of being translated into something that is usable by a more abstract biped model (retargeting). Because of this, non-anatomical Skeletons will not map correctly without some additional tweaking. Starting from plugin version 1.23, you can tweak the alignment of the bone mapping by adding sockets to the Skeleton blueprint:

Adding Sockets to the Bone Mapping

2. Under the Skeleton tree, right-click on the bone that you wish to add the sockets to.

3. Right click and select_Add Socket_.

4. Go to the Animation blueprint, and change the bone mapping of the bone which you have created sockets for, and map it to the socket that was just created.

5. Play the scene, and adjust the socket location from the Skeleton Editor to adjust alignment of the bone.

Overview

The OptiTrack VR driver lets you stream tracking data of the head-mounted display (HMD) and the controllers from Motive into SteamVR. The plugin ships in an installer package (MSI), and it will set up the driver along with a tool for configuring streaming settings. Using this, the tracking data from Motive can be used to override the tracking of the VR system in any applications that are compatible with SteamVR.

Requirements

• Motive version 2.2 or higher

• SteamVR installed on the host computer.

HMD Setup

Place Markers on the HMD

For the camera system to track the HMD, a set of markers must be attached to the HMD. You can either use the active markers (Active HMD clip or Active Tags) or the passive markers. Passive markers are retroreflective markers that reflect infrared light emitted from the IR LEDs on the camera. On the other hand, the active markers are LED markers that emit the IR light and has the intelligence to be uniquely identified.

When using the active markers, you can conveniently put a set of 8 markers onto the HMD by using the HMD Clip, or you can attach the markers from the Tag manually onto the HMD using adhesives and marker posts.

Create HMD Rigid Body in Motive

For using OptiTrack system for VR applications, it is important that the pivot point of HMD Rigid Body gets placed at the appropriate location, which is at the root of the nose in between the eyes. When using the HMD clips, you can utilize the HMD creation tools in the Builder pane to have Motive estimate this spot and place the pivot point accordingly. It utilizes known marker configurations on the clip to precisely positions the pivot point and sets the desired orientation.

Steps

3. Under the Type drop-down menu, select HMD. This will bring up the options for defining an HMD Rigid Body.

4. If the selected marker matches one of the Active clips, it will indicate which type of Active Clip is being used.

5. Under the Orientation drop-down menu, select the desired orientation of the HMD. The orientation used for streaming to Unity is +Z forward and Unreal Engine is +X forward, or you can also specify the expected orientation axis on the client plugin side.

6. Hold the HMD at the center of the tracking volume where all of the active markers are tracked well.

8. Click Create. An HMD Rigid Body will be created from the selected markers and it will initiate the calibration process.

9. During calibration, slowly rotate the HMD to collect data samples in different orientations.

10. Once all necessary samples are collected, the calibrated HMD Rigid Body will be created.

Setting up the OpenVR Driver

Download and run the installer

Open the configuration program

Once the driver has been successfully installed, launch the configuration utility software (C:\Program Files\OptiTrack\OpenVR Driver\ConfigUtil). Using this tool, you can load and check existing configurations and make changes to the settings as needed. To import current settings, click Load and to save out the changes, click Save.

Please make sure you are running this tool with admin privileges; if not, it might not be able to modify the settings properly. If the configuration software detects a running instance of SteamVR through OpenVR, it will be indicated as Initialized at the very top as shown in the image. Please note that when the settings get modified while SteamVR is running, the SteamVR must be restarted to apply the changes.

Configure connection settings

First, configure the connection settings so that the driver listens to the Motive server where the tracking data is streamed from.

Connection Type

Choose between either Unicast or Multicast. This should match the settings within Motive.

Server Address

The server address must match the address where Motive is streaming the data to.

Local Address

The local address must match the IP address of the computer on the network where the driver is installed.

Tracking Type

Choose your tracking type that is applicable to your setup.

• Standard Tracking

  • Standard tracking involves sensor fusion tracking for the HMD along with OptiTrack outside-in tracking for controllers.

• OptiTrack Only

  • OptiTrack only is OptiTrack outside-in tracking that applies to both the HMD and the controllers.

• HMD Tracking Only

  • This tracking uses only the native tracking of the HMD and controllers without OptiTrack input.

Set up the HMD

Save out the configuration

Save the configurations by clicking on Save. This will modify the set of configurations in the steamvr.settings file in the steam installation directory and they will override the HMD tracking with the tracking data from Motive. If you already had an instance of OpenVR or SteamVR running, restart the application to apply the changes.

Confirm the setup

Launch SteamVR. If the driver is successfully set up, you should see a tracker icon added to the right of the HMD icon and the HMD will now be using the motion capture system instead of the base stations. Here, please make sure all of the lighthouse base stations are powered off.

VIVE Controllers

Setting up the controller (optional)

When needed, the Vive controllers can be configured as well. To do so:

• Open the configuration utility tool while SteamVR is running.

• At the top of the configuration tool, it should indicate OpenVR status as Initialized and the controllers must be showing up in SteamVR.

• Then, in the controller sections, enable the controllers, specify the override device using the drop-down menu, and input the corresponding streaming ID of the controller Rigid Bodies in Motive.

• Once everything has been configured, save the changes and restart SteamVR.

• When the override is configured properly, SteamVR will have an additional tracker icon per each enabled controller.

Data Streaming

Now that the driver is set up, the HMD tracking will be overridden by tracking data from the mocap camera system, and you can integrate HMDs into the game engine through their own VR integration.

Streaming settings in Motive

• Broadcast Frame Data must be set to true.

• Local interface must be set to the desired IP address to stream the tracking data from.

• Streaming of Rigid Bodies must be set to True

• For wireless streaming, use Unicast streaming type.

Notes for Unity users

Please make sure the Unity project is configured for OpenVR development. In Unity, open player settings from Edit → Project Settings → Player and select the OpenVR under the Virtual Reality SDK lists. Once this is set up properly, it will play the scene on the HMD.

Unreal Engine

Make sure Unreal Engine is configured for SteamVR development. Please refer to the Unreal Engine's documentation for more information on developing for SteamVR.

Data Port Note

As of the OpenVR Driver 2.1.0 the auto-detection port default is 1513. In the case where a firewall must configure individual ports to allow or disallow data, this port can be used to allow the OpenVR Driver to connect automatically to Motive.

Streaming Rigid Body/Skeleton data

Aligning world coordinates

Client Origin

When using both the VR driver and the plugins (UE/Unity), it is important that the client origin object is located at the origin without any rotations. In other words, it must have the position set to (0,0,0) and the rotation set to (0,0,0).

Notes for Unreal Engine Users

When using the Unreal Engine plugin, you will need to additionally create a custom pawn for properly aligning the coordinate systems between SteamVR and OptiTrack UE plugin:

2. Create a new pawn. Right-click in Content Browser, and from the context menu, select Blueprint → Blueprint Class → Pawn.

3. Load created Blueprint in the editor and add a camera component.

4. (optional) Double-check that the “Lock to HMD” property is set to true under the camera component properties in the details pane.

5. Select the pawn and set the “Base Eye Height” property to 0 in the details pane.

6. Compile the pawn then add it to the scene.

7. Select the pawn and set the “Auto Possess Player” to “Player 0”.

8. The HMD should now be working for Levels built for VR.

This page provides instructions on setting up the OptiTrack OpenVR driver for integrating OptiTrack system with Vive HMDs within SteamVR applications, including Unreal Engine and Unity.

Overview

For integrating Vive HMDs, the OptiTrack OpenVR Driver must be used. This driver lets you track the head-mounted display (HMD) and the VR controllers using OptiTrack motion capture system and stream the tracking data from Motive directly into SteamVR. In other words, this will basically override the tracking from the lighthouse stations. The plugin ships as an installer package (MSI) which will set up the driver along with a utility tool for configuring client streaming settings. Once integrated, the streamed tracking data can be used in any application platform that utilizes SteamVR. For tracking of objects other than the HMDs, please read through the OptiTrack Unreal Engine Plugin page for details.

Supported Systems

• VIVE

• VIVE Pro 1 and 2

• Valve Index

• HP Reverb G2

Unreal Engine Plugin

Unreal Engine 4

When developing for SteamVR applications using the OpenVR Driver to track the HMD in Unreal Engine 4, the OptiTrack - Streaming Client version 2.27 must be used and the OptiTrack - VR Latency Optimization version 2.27 plugin is suggested. The OptiTrack - VR Latency Optimization provides HMD render compensation that helps to minimize the latency in VR application.

Unreal Engine 5

The latest plugins that support Unreal Engine 5 are OptiTrack - Live Link version 3.0 and OptiTrack - Streaming Client version 3.0.

HMD Setup

First of all, setup and optimize the motion capture volume as explained in the Getting Started guide or the Hardware Setup documentation. If you plan to install any obstacles (e.g. walls) within the capture volume, make sure they are non-reflective, and place and orient the cameras so that every corner is thoroughly captured by multiple cameras.

General Setup Steps

1. Attach the markers on the HMD

2. Create a Rigid Body asset

3. Calibrate the Pivot Point of the Rigid Body

4. Configure the Rigid Body settings in Motive

Place Markers on the HMD

For the camera system to track the HMD, a set of markers must be attached to the HMD. You can either use the active markers (Active HMD clip or Active Tags) or the passive markers. Passive markers are retroreflective markers that reflect infrared light emitted from the IR LEDs on the camera. On the other hand, the active markers are LED markers that emit the IR light and has the intelligence to be uniquely identified.

In general, for most VR applications, using active markers is recommended for better tracking stability and ease of use. Active markers also have advantages over passive markers when tracking a large number of objects. For applications that are sensitive to the accuracy of the tracking data, using passive marker may have more benefits. To get more help with finding the best solution for your tracking application, please contact us.

When using the active markers, you can conveniently put a set of 8 markers onto the HMD by using the HMD Clip, or you can attach the markers from the Tag manually onto the HMD using adhesives and marker posts.

Create HMD Rigid Body in Motive

This feature can be used only with HMDs that have the OptiTrack Active HMD clips mounted.

For using OptiTrack system for VR applications, it is important that the pivot point of HMD Rigid Body gets placed at the appropriate location, which is at the root of the nose in between the eyes. When using the HMD clips, you can utilize the HMD creation tools in the Builder pane to have Motive estimate this spot and place the pivot point accordingly. It utilizes known marker configurations on the clip to precisely positions the pivot point and sets the desired orientation.

Steps

1. First, make sure Motive is configured for tracking active markers.

2. Open the Builder pane under View tab and click Rigid Bodies.

3. Under the Type drop-down menu, select HMD. This will bring up the options for defining an HMD Rigid Body.

4. If the selected marker matches one of the Active clips, it will indicate which type of Active Clip is being used.

5. Under the Orientation drop-down menu, select the desired orientation of the HMD. The orientation used for streaming to Unity is +Z forward and Unreal Engine is +X forward, or you can also specify the expected orientation axis on the client plugin side.

6. Hold the HMD at the center of the tracking volume where all of the active markers are tracked well.

7. Select the 8 active markers in the 3D viewport.

8. Click Create. An HMD Rigid Body will be created from the selected markers and it will initiate the calibration process.

9. During calibration, slowly rotate the HMD to collect data samples in different orientations.

10. Once all necessary samples are collected, the calibrated HMD Rigid Body will be created.

Setting up the OpenVR driver

Setup Steps

Download and run the installer

Download the OpenVR driver from the downloads page. Once downloaded, launch the installer and follow the prompts to set up the driver. On the last window, make sure to select Launch Configuration Utility before clicking Finish. This will open the Configuration options to setup your HMD with Motive.

Open the configuration program

Once the driver has been successfully installed, launch the configuration utility software (C:\Program Files\OptiTrack\OpenVR Driver\ConfigUtil). Using this tool, you can load and check existing configurations and make changes to the settings as needed. To import current settings, click Load and to save out the changes, click Save.

Please make sure you are running this tool with admin privileges; if not, it might not be able to modify the settings properly. If the configuration software detects a running instance of SteamVR through OpenVR, it will be indicated as Initialized at the very top as shown in the image. Please note that when the settings get modified while SteamVR is running, the SteamVR must be restarted to apply the changes.

Configure connection settings

First, configure the connection settings so that the driver listens to the Motive server where the tracking data is streamed from. The server address must match the address where Motive is streaming the data to, and the local address must match the IP address of the computer on the network where the driver is installed.

Set up the HMD

In the HMD section, enable the HMD and input the Rigid Body ID of the HMD. The Rigid Body ID must match the Streaming ID property of the HMD Rigid Body definition in Motive.

Save out the configuration

Save the configurations by clicking on Save. This will modify the set of configurations in the steamvr.settings file in the steam installation directory and they will override the HMD tracking with the tracking data from Motive. If you already had an instance of OpenVR or SteamVR running, restart the application to apply the changes.

Confirm the setup

Launch SteamVR. If the driver is successfully set up, you should see a tracker icon added to the right of the HMD icon and the HMD will now be using the motion capture system instead of the base stations. Here, please make sure all of the lighthouse base stations are powered off.

VIVE Controllers

Setting up the controller (optional)

When needed, the Vive controllers can be configured as well. To do so, open the configuration utility tool while SteamVR is running. At the top of the configuration tool, it should indicate OpenVR status as Initialized and the controllers must be showing up in SteamVR. Then, in the controller sections, enable the controllers, specify the override device using the drop-down menu, and input the corresponding streaming ID of the controller Rigid Bodies in Motive. Once everything has been configured, save the changes and restart SteamVR. When the override is configured properly, SteamVR will have an additional tracker icon per each enabled controller.

Data Streaming

Now that the driver is set up, the HMD tracking will be overridden by tracking data from the mocap camera system, and you can integrate HMDs into the game engine through their own VR integration.

Streaming settings in Motive

First, make sure the streaming settings are configured in Motive for streaming out the data. For more information regarding streaming in Motive please visit our Streaming wiki page:

• Enable must be set to toggled on.

• Local interface must be set to the desired IP address to stream the tracking data from.

• Streaming of Rigid Bodies must be set to True

• For wireless streaming, use Unicast streaming type.

Confirm the Connection

Once Motive is configured for streaming, launch SteamVR home to check the connection. If everything is setup correctly, you should be able to move around, or translate, within the scene freely. You may also need to check the ground plane to make sure it's well aligned.

If you experience any unexpected rotations in the view as you move your head, it could indicate that the HMD pivot point has not been calibrated properly. Please revisit the HMD Setup section and make sure the HMD Rigid Body pivot point is positioned and oriented at the expected pivot; which is at the root of nose with z-forward.

Developing in Unreal Engine

Make sure Unreal Engine is configured for SteamVR development. Please refer to the Unreal Engine's documentation for more information on developing for SteamVR.

Developing for SteamVR

Streaming Rigid Body/Skeleton data

This driver is designed for streaming of HMD and controller tracking data only. For streaming tracking data of other Rigid Body objects, you will need to use the corresponding plugins (UnrealEngine or Unity). In other words, the HMD tracking data will be streamed through the SteamVR using the driver you've installed, and all other tracking data will be streamed through the plugin.

Aligning world coordinates with the UE plugin

Client Origin

When using the OpenVR driver for the HMD and the game engine plugins (UE/Unity) for other types of tracking data, including Rigid Body data, the client origin object must be located at the global origin without any rotations. In other words, the position must be set to (0,0,0) and the rotation must be set to (0,0,0) on the client origin. This is important because this will align the coordinate system from the (UE/Unity) plugin with the coordinate system in OpenVR pipeline

Notes for Unreal Engine Users

When using the Unreal Engine plugin, you will need to additionally create a custom pawn for properly aligning the coordinate systems between SteamVR and OptiTrack UE plugin:

1. Create an "OptTrack Client Origin" to the scene and set the relevant connection info. Refer to the OptiTrack Unreal Engine Plugin page for more information on setting up the client origin.

2. Create a new pawn. Right-click in Content Browser, and from the context menu, select Blueprint → Blueprint Class → Pawn.

3. Load created Blueprint in the editor and add a camera component.

4. (optional) Double-check that the “Lock to HMD” property is set to true under the camera component properties in the details pane.

5. Select the pawn and set the “Base Eye Height” property to 0 in the details pane.

6. Compile the pawn then add it to the scene.

7. Select the pawn and set the “Auto Possess Player” to “Player 0”.

8. The HMD should now be working for Levels built for VR.

Overview

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.

Setup

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

• 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.

Using the Plugin

Static Meshes or Camera Actors

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.

Timecode Setup

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.

Skeletons

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.

MetaHumans

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.

1. Find the Skeletal Mesh

Navigate to the Skeletal Mesh for your MetaHuman. This is typically located in a folder such as MetaHumans > [Name] > [Female/Male] > [Height] > [Weight] > Body. Double click the Skeletal Mesh to open the blueprint.

2. Open the AnimGraph Tab

Click the "Blueprint" option on the top bar of new window. In the bottom left corner navigate to My Blueprint > Animation Graphs > AnimGraph and double click.

3. Hook up your Blueprint

You'll see a very complex AnimGraph already setup. Make a new Live Link Pose object like in the Skeleton creation steps. Connect the Input Pose or Control Rig to the input of the Live Link Pose. Connect the output of the Live Link Pose to the Output Pose AnimGraph object.

4. Retarget in the Details Tab

The last step in this window is to set the Retarget Asset to OptiTrackLiveLinkRetarget for the Live Link Pose node. To do this, simply click on the dropdown in the Details tab and click the dropdown under Retarget Asset and select OptiTrackLiveLinkRetarget. After it has been set, click Compile in the top left of this window. You may now close this window and move on to the next steps.

5. Level of Detail (LOD)

MetaHumans will change their Level of Detail (LOD), i.e. how complex the asset is, based on how far the camera is from the actor among other factors. In order for things to animate correctly the Forced LOD must be a minimum of 1 (default of -1). To change this setting, click on the (Instance) you wish to change in the Details tab on the main workspace window. Below the selected (Instance) select the LOD tab. From here you can change the value in the Forced LOD Model field.

6. Animate your MetaHuman

At this point if you drag the base MetaHuman object into the scene then it will animate like other Skeletons.

Standalone Game Mode

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.

MotionBuilder Retargeting

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.

Troubleshooting

The Live Link Skeletal Mesh Generator is a third-party plugin and is not supported by OptiTrack. More details of this plugin can be found here: Live Link Skeletal Mesh Generator Plugin.

Required Components

• Live Link Skeletal Mesh Generator Plugin

• Unreal Engine 5.1

• Motive 3.0

• Visual Studio 2019+

Visual Studio Setup

1. Install Visual Studio 2019 or higher

2. During installation, from the Workloads tab make sure to select 'Game Development with C++'

Unreal Engine Skeletal Mesh Generator Installation

1. Disable any OptiTrack plugins in UE5.1

2. From your project navigate to Tools > New C++ Class

3. Select 'None' from the Add C++ Class window

4. Name your class (i.e. 'StarterClass')

5. In order for this to be applied, you'll need to save and close Unreal

6. Find your project in the file directory you chose to save it in

7. Open the generated solution file and verify that you can select the green play button from top toolbar

8. This will open the Unreal Editor, close the Unreal Editor and the solution

9. Move the Skeletal Mesh Generator Plugin into the Plugins folder of your project files.

10. Restart the solution/editor and enable: The 'Skeletal Mesh Generator Plugin', 'Geometry script', and 'Skeletal Mesh Modeling tools'.

11. Re-enabled OptiTrack LiveLink Plugin.

12. You should now be able to use the Skeletal Mesh Generator Plugin under Plugins > SkeletonGenerator Content > Widgets.

13. To view the Skeletal Mesh Generator widget, right click on the BLU_SkelmeshFromLiveLink and select Run Editor Utility Widget.

Additional Notes

HMD Marker Setup

When manually positioning the appropriate location of the Rigid Body pivot point, you will need to have landmark markers on specific locations.

Attachment

When attaching retroreflective markers, make sure markers are securely attached and readily captured by the cameras. For attaching the markers, we recommend using our 20 mm wide and 30 mm tall M4 threaded plastic marker bases with Acrylic adhesives, available at the , to attach the markers onto the HMD.

Placement

A markered HMD will be defined as a Rigid Body in Motive. When placing markers, make sure the placement is respected in the arrangement within the HMD. Also, the marker arrangements between multiple HMDs must be incongruent. For more details, read about marker placement from the page. Also, for tracking the HMD, two landmark markers must be placed in the following locations:

Eye-level Side Markers (2)

Place two markers on left and right side of the HMD, these markers will serve two additional purposes. First, they will indicate yaw of the HMD, and they will be used to align the Rigid Body orientation with the orientation of the actual HMD component. Thus, a line interconnecting the two markers must be parallel to the frontal plane, or the display, of the HMD. Second, these markers will be used to locate the elevation of the eyes when creating the Rigid Body in Motive. In summary, the two landmark markers must be carefully placed considering the following:

• The markers should align along eye-level of the user when the HMD is mounted.

• Most importantly, place these markers in the exactly same location of the left and right side so that they form a precisely symmetrical arrangement.

• Same dimension attachment bases must be used for both of the markers.

Pivot Point Position

3. Translate the pivot point along the z-axis using the translation tool. For the most accurate position, you may need to physically measure the sagittal, z-axis, distance from the landmark marker to the root of nose, and apply the measured offset.

Orientation

• In Unreal Engine: the X-axis of the HMD Rigid Body must be directed forward.

• In Unity: the Z-axis of the HMD Rigid Body must be directed forward.

Overview

The allows you to stream real-time Rigid Body, skeleton, and HMD tracking data from Motive into Unity. Using the streamed data, objects and characters in the scene can be animated. The plugin contents are distributed in unitypackage format, and you can simply load this file into Unity projects to import its contents. Once imported, included C# scripts can be used for instantiating a client origin and receiving the tracking data. This article focuses on how to set up and use the plugin.

Versions Requirements

• Unity Version: 2017.2 / 2017.1 or above. (2020.3+ recommended)

• Visual Studio 2019 or latest Visual C++ Redistributable

Motive Setup (Server)

Streaming Setup

Streaming in Motive

• Enable - Turn on the Enable setting at the top of the NatNet section.

• Local Interface - Choose the desired IP network address from this dropdown to stream data over.

• Transmission Type - Typically you will want to set this to Unicast since it subscribes only to the data you wish to use and normally uses less network bandwidth. This is especially advised if streaming data over WiFi.

• (Optional) If using Multicast, then enable/disable the desired data types. For tracking HMDs, disabling the Marker streaming is advised.

Unity Setup (Client)

Import Plugin Package

While in the Unity project, double-click on the plugin unitypackage file and import the plugin assets into the project. When the package has been successfully imported, the following contents will be available within the project:

Plugin Contents

Setting Up the Client Object

In order to receive tracking data from a server application (e.g. Motive), a client object must be set up. The OptitrackStreamingClient.cs script can be attached to any object to stream data relative to that object. Typically, this script is attached to an empty object or loaded in using the "Client - OptiTrack" prefab object in the Assets/Optitrack/Prefabs folder.

• [Unity] Under the Prefabs folder, import the "Client - OptiTrack" prefab object into the scene, or attach OptitrackStreamingClient.cs script onto an empty object.

• [Unity] In the streaming Client object, configure the connection settings to match the streaming settings in Motive.

• Server Address - IP address of the PC that the server application (Motive) is running on.

• Local Address - Local IP Address of the PC that the client application (Unity) is running on. (Typically, this looks similar to the Server Address except maybe the last digits.)

• Connection Type - Must match Motive. Unicast is recommended.

• [Unity] If you wish to receive tracking data from more than one server instances, you may create multiple objects with the client script attached.

Animating Rigid Body

1. [Unity] On an object that you wish to animate, attach the OpitrackRigidBody.cs script.

2. [Unity] In the Streaming Client entry, link the Client object in which the OptitrackStreamingClient.cs script is attached. By default, it searches for an existing client instance, but this must be specified when there are more than one streaming client objects.

4. [Motive] Make sure Motive is tracking and streaming the data.

5. [Unity] Play the scene. The linked object will be animated according to the associated Rigid Body movement in Motive.

Animating Skeleton

Steps

1. [Unity] On Unity characters, attach OptitrackSkeletonAnimator.cs script as one of its components.

2. [Unity] For the Streaming Client entry, link the Client object in which the OptitrackStreamingClient.cs script is attached. By default, it searches for an existing client instance, but this must be specified when there are more than one streaming client objects.

3. [Unity] Enter Skeleton Asset Name which is assigned in Motive

4. [Unity] For the Destination Avatar entry, link to the character's avatar component.

5. [Motive] Make sure Motive is tracking and streaming the data.

6. [Unity] Play the scene. When everything is set up properly, the linked avatar in Unity will be animated according to the streamed skeleton in Motive. The position of the actor will be in its reference position as explained above.

Animating Markers, Etc.

1. [Unity] On the OptiTrack Streaming instance, enable the Draw Markers, "Draw Cameras", or "Draw Force Plates" setting(s).

2. [Motive] Make sure that marker streaming is enabled in Motive if you wish to visualize markers.

3. [Unity] Make sure the streaming setting is set up correctly, and play the scene.

4. [Unity] Each marker, camera, or force plate will be drawn in the scene, as shown in the screenshot below. (Note: Only markers will animate.)\

Integrating HMDs

Wireless Multiplayer Setup

When setting up multiplayer games with wireless clients, it is more beneficial for each client to make direct connection to both the tracking-server (Motive) and the game-server, rather than rebroadcasting the streamed tracking data through the game-server. Then, any of the game related actions that interacts with the tracking data can be processed on the game-server, and this server can send out the corresponding updates to the wireless clients. This allows the wireless clients to only receive both the tracking data or updates without having to send back any information; in other words, minimizing the number of data transfers needed. If wireless clients are sending data there will be a minimum of two transfers on the wireless network, and each transfer of data through wireless network is at risk of latency or lost packets.

Overview

Specs

This page provides instructions on how to configure VCS inputs in Unreal Engine. The basic configuration is similar to configuring any other input triggers in Unreal Engine. Please note that only one VCS controller can be connected and configured due to some limitations. Having two controllers connected at the same time is not supported.

Setup Steps

Create VCS Rigid Body in Motive

Create a Rigid Body from your tracking controller’s markers using the Builder pane or by selecting the markers and using the keyboard hotkey CTRL + T. You'll want to orient the controller along the +Z axis during creation to define the 'neutral' or 'zero' orientation.

Configure Data Streaming settings

In Motive, configure the data streaming settings. Use the Data Streaming pane to configure streamed packets. Make sure Rigid Body data is streamed out in order to use VCS.

Create/load an UE Project

Start up a project in Unreal Engine (UE).

Enable Windows RawInput plugin

Go to Edit tab → Plugins to open the plugins panel. Enable the Windows RawInput plugin under the Input Devices group.

Connect VCS plugin through the enabled plugin

In Edit tab → Project Settings, scroll to the bottom on the left side panel until you see Raw Input under the plugins group. Here you will let UE project know which input devices to use.

Find Hardware ID and Product ID of the VCS controllers

To find these IDs, you will need to look at the windows device properties. Go to Windows Control Panel -> Devices and Printers. Then right-click on the VCS controllers to access its properties. In the properties, go to the Hardware tab and click properties for “HID-compliant game controller”.

Once you access the controller properties, go to the details tab. Select Hardware ID in the drop-down menu and the hardware ID (HID) and product ID (PID) will be shown under the highlighted section.

Input the IDs in UE

Under the project settings panel Raw Input plugin properties, input both the vendor ID (Hardware ID) and the product ID (PID) that was found under the controller properties.

Register the Input Buttons

Now the project has the IDs to look for the controllers, next step is to setup and register the input buttons. To do so, you will play the project scene, and trigger on the buttons to register them.

In UE, hit Play and press (~) to access the console. In the console, input command ShowDebug INPUT". This will list out all of the input actions on the left side of the viewport.

Use the keys to register

Use all of the keys on the controller to register the inputs; total three axis and seven buttons. Please note that these keys may not exactly match the keys on your controller.

• Axis 1: Joystick left/right

• Axis 2: Joystick up/down

• Axis 3: Nob rotate

• Button 1: Blue

• Button 2: Black

• Button 3: White

• Button 4: Red

• Button 6: Joystick click

• Button 7: Nob click

Map the Registered Inputs

Now that the buttons have been registered, next step is to map the keys. They will be mapped under Edit → Project Settings → Inputs. Choose either the Axis mapping or the action mapping to map the controls to desired actions.

Use the Registered Inputs

Now that all of the buttons are set up, use them to control the VCS in UE.

This page briefly goes over the active finger marker set and how it needs to be set up.

Overview

The active finger Marker Set utilizes the tracking capability of active markers and its active labeling features to accomplish tracking of both the hands and the fingers. These Marker Sets require the active marker tracking solution and the Tag(s). Wired from an active Tag, each active marker must attach to the expected locations. For each hand, 10 active markers are needed for each hand.

Requirements

• The Active Base Station

• Active Tag(s) with active markers.

• A way to attach active markers onto the hands (e.g. gloves).

Below Marker Sets uses active finger tracking

• Baseline + Active Fingers (57)

• Core + Active Fingers (62)

• Right Hand + Active Fingers (10)

• Left Hand + Active Fingers (10)

Marker Placement

• Total 11 markers will be attached on each hand.

• Tags: Attach Tags to each hand for the active LEDs.

• Active Markers (10): Each Tag connects up to 8 active markers. Position the wired active markers at the tip of all five fingers (5), one each on the knuckle of the index finger and the pinky finger (2), and lastly, place the remaining active marker on the inside (medial side) of the wrist axis.

Creating the hand

Steps for creating an active finger Marker Set is the same as the other Skeleton Marker Sets:

1. Open the Builder pane and select the desired hand Marker Set under the drop-down menu.

2. Make sure all of the markers are placed in the correct positions. For the Core + Active Fingers (62) Marker Set, please make sure the passive full body tracking markers are also placed on the person's body.

3. Once the markers have been placed, ask the subject to strike the calibration pose.

4. Select the finger markers in the 3D viewport.

5. The Marker Detected must match Marker Required in the Builder pane.

6. Click Create.

This article provides instructions on how to synchronize an OptiTrack Motion Capture system with an HTC Vive virtual reality system, specifically the lighthouse base stations, to avoid overlapping of the infrared tracking lights. The HTC Vive system also uses infrared LEDs and lasers for tracking its head-mounted display (HMD) and controllers. When using an OptiTrack mocap system in conjunction with the HTC Vive system, the infrared tracking from the two systems can interfere with each other. For this reason, the two systems must be synchronized in a way so that the two different tracking lights do not temporally overlap. Currently, sync configurations with only OptiTrack Prime-series camera systems have been tested.

Let’s go through the synchronization setup. The following setup instructions assume that the two tracking base stations of the HTC Vive system are set to channel b and c and are optically synchronized. The channel b base station will serve as the master device for synchronizing the two systems. Sync out signal from the channel b station will feed into one of the input ports on the eSync 2, and a sync offset (specified in microseconds, or μs) will be applied to so that IR lights from the two systems don’t interfere with each other. The following section describes the instructions in detail.

Synchronization Configuration

Step 1: Set up the HTC Vive system.

The base stations will synchronize optically in this setup. Refer to the respective documentation for more details on setting up the HTC Vive system. Set the tracking stations to channels b and c, so that they are optically synchronized (in the absence of a sync cable connection between them).

Step 2: Set up the OptiTrack mocap system.

Refer to the Hardware Setup wiki pages for more details.

Step 3: Connect the sync output from the channel b base station into the input port 1 of the eSync 2 synchronization hub.

The sync output of the base stations use 3.5 mm stereo (TRS) cables, whereas the Input ports of the eSync 2 are BNC ports. You will need to use a stereo female to RCA male adapter (e.g. http://www.monoprice.com/product?p_id=5612) as well as an RCA-to-BNC adaptor (included with the eSync 2) to connect the channel b base station and the eSync 2 hub. After attaching the stereo to RCA adaptor, connect the red RCA cable into the eSync 2 using a BNC adapter, as shown in the following photo.

Step 4: Motive: Synchronization pane. Configure the synchronization in Motive.

Open the Synchronization pane in Motive, and set the synchronization type to Custom Synchronization.

Step 5: Motive: Synchronization pane. Configure the Sync Input.

Set the Sync Input to Input 1, which was the input port of the eSync 2 where the sync cable was connected to. If the sync cable is properly connected and the HTC Vive system is properly working, the bottom signal monitor will display a frequency of approximately 60 Hz detected through the Input 1 port of the eSync 2. Note that this configuration will synchronize the OptiTrack camera system to the sync signal coming through the Input port.

Step 6: Motive: Synchronization pane. Introduce Sync Offset (μs).

Now that the OptiTrack system’s shutter timing is synchronized with the base stations of the HTC Vive system, you will need to introduce a sync offset to avoid overlapping of the tracking lights. The following list of offset sync parameters are tested to avoid the interference. Input these parameters into the Synchronization pane. If you wish to increase the final frame rate of the mocap system, you will need to apply a multiplier.

• Final Frame Rate: 120 Hz

• Sync Multiplier: 2

• Sync Offset: 1780 μs

• Final Frame Rate: 240 Hz

• Sync Multiplier: 4

• Sync Offset: 3150 μs

Step 7: Motive: Synchronization pane. Apply sync configuration.

Press Apply to employ the sync configuration. The tracking IR lights from both systems will no longer interfere, and the HTC Vive components will be working properly and available in the SteamVR application.

Step 8: Motive: Cameras pane. Lower the camera exposure on the OptiTrack system.

Another important note is that high camera exposure settings may cause IR light from the base stations to be detected by the OptiTrack system. It's suggested to keep the camera exposure below 1000 us for all of the cameras.

Now that the two systems are synchronized to avoid the IR interference, both systems can be used together to provide immersive VR experiences. Note that the instructions listed on this page are tested to work with HTC Vive system, but alternative approaches may also be possible.

Overview

This page provides general instructions on how to use the OptiHub2 for integrating external devices with Flex series mocap systems. The OptiHub2 not only provides power for the USB cameras, but it also includes external sync in/out ports for integration of external devices. With proper configurations, you can have another device (parent) control the mocap system or have the mocap system control another external device (child), or both. Setup instructions for both child and parent devices will be covered. Note that the sync setup may vary depending on the type of integrated devices as well as the morphology of the communicated sync signals. Use this guide for understanding the general idea of how external devices are implemented, and apply it to your own needs.

External Device Synchronization

On the OptiHub2, there are one External SYNC In and one External SYNC Out ports for connecting external devices. In general, parent devices connect to the input port for controlling the mocap system, and child devices connect to the output port to be triggered by the mocap system. Once the devices are connected, the input and output source needs to be configured under the in Motive.

Additional Notes:

• Unlike the eSync2, the OptiHub2 cannot generate an output signal at a higher frequency than the camera capture rate.

• When using multiple OptiHub2s, input and output ports of only the parent OptiHub2 can be used. The parent OptiHub2 is the first OptiHub2 within the daisy-chained RCA sync chain.

Synchronization Setup

Setting Up a Parent Device

Step 1. [Hardware] Connect a parent device into the External SYNC In port of the parent OptiHub2.

Step 2. [Motive] Launch Motive.

Setting Up a Child Device

Step 1. [Hardware] Connect a child device into the External SYNC Out port of the parent OptiHub2.

Step 2. [Motive] Launch Motive.

Step 6. [Motive] Once this is set, the OptiHub2 will output configured signal through its output ports.

Input Source

The Sync Input configuration determines how the camera system is synchronized. Depending on which input source is configured under the custom sync settings, the cameras will shutter at the corresponding frequency. To configure the sync input signals, first define an input Source and then configure the respective trigger settings. The following input sources can be configured with the OptiHub2:

Internal Sync

(The camera system will be the parent)

When the sync source is set to Internal/Wired the camera system uses the OptiHub2 as the sync source. This is the default configuration, and it uses OptiHub2's sync protocol for synchronizing the cameras. The Parent OptiHub2 will generate an internal sync signal which will be propagated to other (child) OptiHub2(s) via the Hub Sync Out Jack and Hub Sync In Jack, and all of the cameras connected to the OptiHub2s will be synchronized. For V100:R1(legacy) and the Slim 3U cameras, Wired Sync protocol is used. In this mode, the internal sync signal will still be generated but it will be routed directly to the cameras via daisy-chained sync cables.

When the Internal Sync is selected as the sync source, Internal Sync Freq (Hz) can be set under the Synchronization Control section. This setting determines how the OptiHub2 triggers the camera exposures or the camera framerate.

Sync In

(The camera system will be the child)

When synchronizing the camera system to an external device, set the source to Sync In, and the camera system references the external signal through the SYNC In port as the parent sync. In this mode, the Input Trigger event must be defined so that the camera systems respond to the incoming signal as desired; available triggers are Either Edge, Rising Edge, Falling Edge, High Gated, and Low Gated. Note that the suitable event will vary depending on characteristics of the received signal and how you want the system to synchronize with it.

For syncing to input signals with a frequency higher than the supported camera frame rates, the Input Divider can be applied so that the sync source is down-sampled to the supported rate range.

USB Sync

(The camera system will be the child)

Trigger and Camera Exposure

Note that the precise moment of the camera exposure does not exactly coincide with the sync input trigger event. There is a fixed latency between these two events due to specific implementation of the sensors used in the cameras. This delay from the onset of the trigger-event to the start of exposure on the cameras can be calculated as the following:

Flex 3 and Duo/Trio tracking bars

• Camera exposure (measured in scanlines for Flex 3 cameras)

Flex 13

Output Source

• All output signals can be inverted by setting the Output::Polarity to Inverted.

• For connecting more than one child devices, output signals may be split using a BNC splitter.

• The sync hubs are capable of sending out the following signals:

Exposure Time & Gated Exposure Time

Exposure output signals to inform when the cameras are exposing. When the output type is set to Exposure Time, the sync hub asserts the output signals when the cameras are exposing, or shuttering, in the live mode. When the output is configured to Recording Pulse, the exposure signal is asserted only when Motive is recording.

Recording Gate

The Recording Gate signal can be used to tell the child device when Motive is recording or not. When configured to Recording Gate, the sync hub will output a constant high voltage signal when Motive is recording. Please note that OptiHub2 is not specifically designed for precise synchronization, and there will be a slight delay when it starts outputting the trigger signal. This delay varies on each camera system setup.

Pass-Through

The Pass-through type outputs the signal that is received through the SYNC In port.

Overview

This page provides instructions on configuring the active components, Active Tags and/or Active Pucks, that are equipped with inertial measurement unit (IMU) sensors. By fusing the optical tracking data of the active markers with the IMU data, Motive can further stabilize the rotational tracking of the Rigid Bodies and accommodate for tiny jitters throughout the tracking. This is recommended for applications where the stability of rotation tracking data is important, including tracking cameras in virtual production applications, tracking drones in low camera-count setups, and more.

Requirements

• Motive version 2.2 to 2.3.1

• IMU Active Batch Programmer

• Base Station: Firmware 2.2.2 or above

• IMU Active Tags/Pucks: Firmware 2.2.1 or above

Additional Information

• When configured, each Active Base Station can communicate with up to 7 IMU Tags/Pucks.

• When needed, multiple Base Stations can be plugged into the same camera network; as long as they are communicating through a separate channel.

• To use the IMU components, all of the devices, including the Base Station, must have firmware version 2.x or above installed. Please follow the instruction below to check the firmware versions on each device.

Active Component Setup

For the IMU data to be used for tracking in Motive, unique Uplink IDs must be assigned onto each IMU Tag or Puck using the active batch programmer program. Then, the Uplink IDs will need to be inputted under the properties of the corresponding Rigid Bodies in Motive. Please follow the steps below:

1) Download Active Batch Programmer

Use the following link to download the batch programmer used for 2.x firmware. Once downloaded, unzip the downloaded file and launch the EXE file.

• Batch Programmer Download:

• OptiTrack Downloads: Active Batch Programmer

2) Check the firmware version and existing configuration

Before setting up the components, we will want to check the existing configurations on the Base Station, Tags, and/or Pucks. To check this, enable the ‘’Read-Only Mode’’ check box at the bottom-left corner of the active batch programmer, and then connect the devices one at a time via USB. Each time a new active component is detected, existing configurations including the firmware version will get listed under the Log section. If any of the settings do not meet the below requirements, you can re-configure them in the next step.

Firmware Version

In order to use IMU Tags/Pucks, all of the active components must have firmware version 2.2.x or above installed. Please check the firmware version on the active components. If the installed firmware is an older version, please contact us for assistance with upgrading the firmware.

RF Channel

Please make sure that all of the active components are communicating through the same channel. Check this and take a note of the channel value as this will also need to be inputted into Motive for IMU data. The RF channel can be set anywhere between 11-26.

Label

The Labels are active IDs assigned to each marker, and it's important that there are no overlapping labels, or IDs, assigned to the same batch of active Tags/Pucks. This setting is applicable to Active Tags/Pucks only.

After checking the settings, you can unplug the device and connect the next one to check the settings.

3) Configure the settings in the Active Batch Programmer

Now that we understand the existing configurations and what needs to be changed, we can configure the active components. To do this, disable the Read-Only Mode in the batch programmer, and settings configured in the IMU batch programmer will get applied to each newly connected device. Please note that this could also reset the existing configuration, thus, make sure to configure only the settings that need to be changed.

Configure Uplink ID

For IMU Tags or Pucks, unique Uplink IDs need to be assigned for each of them. For doing this, simply check the box next to the Uplink ID whenever we are configuring IMU Tags or Pucks.

RF Channel/Label

Uncheck the boxes next to "Set marker labels" and "Set radio options" unless they also need to be reconfigured.

All of the Tags/Pucks are pre-configured for every set of devices that gets shipped out in the same order, and we also make sure none of the Labels overlap. Thus, users should not need to use this batch programmer in general. The cases when you would want to reconfigure the active components are: 1) When you have purchased new Tags/Pucks to add to the system from the previous order. 2) When there is a need to change the RF communication channel to avoid interferences.

In cases where marker labels or RF channels need to be reconfigured, enable the box next to the corresponding setting in the batch programmer. DO NOT check the box unless the settings need to be changed. When reconfiguring marker labels, ALL of the Tags and Pucks will need to be reconfigured at once, so that the labels do not overlap with other components in the system.

4) Connect an active component

Once we have configured the settings in the batch programmer, connect Active Tags or Pucks one at a time and the programmer will apply the configured settings to the newly connected device, and it will also make sure that the IDs do not overlap in the same batch. Once the settings get applied the details will get listed under the Log.

It’s recommended to note the assigned Uplink IDs for each Tag/Puck so that we can track down the settings easily when needed.

5) Disconnect and connect remaining devices

Once a device is configured, disconnect and connect the next device to apply the same settings and unique IDs. Repeat this for all of the active components that need to be configured.

Tag Attachment to Tracked Objects

When using an IMU Active Tag to create a custom Rigid Body, please make sure both the PCB board of the tag and the LEDs are securely attached and rigidly constrained to the object. The IMU sensor fusion will not work correctly if either the markers or the tag are not secured to the rigid object.

Motive Setup

Now that each of the IMU Tags/Pucks has been assigned with an Uplink ID, the next step is to input this ID into the properties of the corresponding Rigid Bodies in Motive. Also, the RF channel configured for each active component will need to be inputted as well. Follow the below steps to assign Active Tag ID and Active RF Channel property for each Rigid Body:

1) Launch Motive

Make sure the configured Active Base Station is connected to the camera system and launch Motive.

2) Power the IMU Tag/Puck

Click the power button on the Tag/Puck to start the device. When the Tag/Puck first initializes, the status LEDs will start blink in red and orange rapidly. This indicates that the IMU sensor is attempting to initialize. At this stage, keep the IMU Tag/Puck stationary until the status LED blinks in green indicating that it has completed the initialization.

3) Create a Rigid Body

Select the active markers associated with a Tag/Puck and create a Rigid Body.

4) Access advanced rigid properties

Open the Properties pane and select the Rigid Body. Reveal the advanced properties by clicking on "..." menu at the top-right and selecting Show Advanced.

5) Input IMU Properties: Active Tag ID and RF Channel

Scroll down to find the IMU section and input the "Uplink ID" value for the corresponding Tag/Puck into. Additionally, input the "RF Channel" used the the corresponding Base Station. Once this is completed the Rigid Body should have the correct properties set to use the IMU in the tag. You can also adjust the Sensor Fusion property to balance the contribution between optical tracking data and IMU data for the Rigid Body solve.

6) Check the status

At this point, the IMU Tags and Pucks are ready to be used. The color of the Rigid Body indicates the status of the IMU data stream.

This page provides instructions on setting up the OptiTrack OpenVR driver for integrating OptiTrack system with Vive HMDs within SteamVR applications; including Unreal Engine and Unity.

Overview

For integrating Vive / Vive Pro / Valve Index HMDs, the OptiTrack OpenVR Driver must be used. This driver lets you track the head-mounted display (HMD) and the VR controllers using OptiTrack motion capture system and stream the tracking data from Motive directly into SteamVR. In other words, this will basically override the tracking from the lighthouse stations. The plugin ships as an installer package (MSI) which will set up the driver along with a utility tool for configuring client streaming settings. Once integrated, the streamed tracking data can be used in any application platform that utilizes SteamVR. For tracking of objects other than the HMDs, please read through the OptiTrack Unity Plugin page for details.

Supported Systems

• VIVE

• VIVE Pro 1 and 2

• Valve Index

• HP Reverb G2

HMD Setup

First of all, setup and optimize the motion capture volume as explained in the Getting Started guide or the Hardware Setup documentation. If you plan to install any obstacles (e.g. walls) within the capture volume, make sure they are non-reflective, and place and orient the cameras so that every corner is thoroughly captured by multiple cameras.

General Setup Steps

1. Attach the markers on the HMD

2. Create a Rigid Body asset

3. Calibrate the Pivot Point of the Rigid Body

4. Configure the Rigid Body settings in Motive

Place Markers on the HMD

For the camera system to track the HMD, a set of markers must be attached to the HMD. You can either use the active markers (Active HMD clip or Active Tags) or the passive markers. Passive markers are retroreflective markers that reflect infrared light emitted from the IR LEDs on the camera. On the other hand, the active markers are LED markers that emit the IR light and has the intelligence to be uniquely identified.

In general, for most VR applications, using active markers is recommended for better tracking stability and ease of use. Active markers also have advantages over passive markers when tracking a large number of objects. For applications that are sensitive to the accuracy of the tracking data, using passive marker may have more benefits. To get more help with finding the best solution for your tracking application, please contact us.

When using the active markers, you can conveniently put a set of 8 markers onto the HMD by using the HMD Clip, or you can attach the markers from the Tag manually onto the HMD using adhesives and marker posts.

Create HMD Rigid Body in Motive

This feature can be used only with HMDs that have the OptiTrack Active HMD clips mounted.

For using OptiTrack system for VR applications, it is important that the pivot point of HMD Rigid Body gets placed at the appropriate location, which is at the root of the nose in between the eyes. When using the HMD clips, you can utilize the HMD creation tools in the Builder pane to have Motive estimate this spot and place the pivot point accordingly. It utilizes known marker configurations on the clip to precisely positions the pivot point and sets the desired orientation.

Steps

1. First of all, make sure Motive is configured for tracking active markers.

2. Open the Builder pane under View tab and click Rigid Bodies.

3. Under the Type drop-down menu, select HMD. This will bring up the options for defining an HMD Rigid Body.

4. If the selected marker matches one of the Active clips, it will indicate which type of Active Clip is being used.

5. Under the Orientation drop-down menu, select the desired orientation of the HMD. The orientation used for streaming to Unity is +Z forward and Unreal Engine is +X forward, or you can also specify the expected orientation axis on the client plugin side.

6. Hold the HMD at the center of the tracking volume where all of the active markers are tracked well.

7. Select the 8 active markers in the 3D viewport.

8. Click Create. An HMD Rigid Body will be created from the selected markers and it will initiate the calibration process.

9. During calibration, slowly rotate the HMD to collect data samples in different orientations.

10. Once all necessary samples are collected, the calibrated HMD Rigid Body will be created.

Setting up the OpenVR driver

Setup Steps

Download and run the installer

Download the OpenVR driver from the downloads page. Once downloaded, launch the installer and follow the prompts to set up the driver. On the last window, make sure to select Launch Configuration Utility before clicking Finish. This will open the Configuration options to setup your HMD with Motive.

Open the configuration program

Once the driver has been successfully installed, launch the configuration utility software (C:\Program Files\OptiTrack\OpenVR Driver\ConfigUtil). Using this tool, you can load and check existing configurations and make changes to the settings as needed. To import current settings, click Load and to save out the changes, click Save.

Please make sure you are running this tool with admin privileges; if not, it might not be able to modify the settings properly. If the configuration software detects a running instance of SteamVR through OpenVR, it will be indicated as Initialized at the very top as shown in the image. Please note that when the settings get modified while SteamVR is running, the SteamVR must be restarted to apply the changes.

Configure connection settings

First, configure the connection settings so that the driver listens to the Motive server where the tracking data is streamed from. The server address must match the address where Motive is streaming the data to, and the local address must match the IP address of the computer on the network where the driver is installed.

Set up the HMD

In the HMD section, enable the HMD and input the Rigid Body ID of the HMD. The Rigid Body ID must match the Streaming ID property of the HMD Rigid Body definition in Motive.

Save out the configuration

Save the configurations by clicking on Save. This will modify the set of configurations in the steamvr.settings file in the steam installation directory and they will override the HMD tracking with the tracking data from Motive. If you already had an instance of OpenVR or SteamVR running, restart the application to apply the changes.

Confirm the setup

Launch SteamVR. If the driver is successfully set up, you should see a tracker icon added to the right of the HMD icon and the HMD will now be using the motion capture system instead of the base stations. Here, please make sure all of the lighthouse base stations are powered off.

VIVE Controllers

Setting up the controller (optional)

When needed, the Vive controllers can be configured as well. To do so, open the configuration utility tool while SteamVR is running. At the top of the configuration tool, it should indicate OpenVR status as Initialized and the controllers must be showing up in SteamVR. Then, in the controller sections, enable the controllers, specify the override device using the drop-down menu, and input the corresponding streaming ID of the controller Rigid Bodies in Motive. Once everything has been configured, save the changes and restart SteamVR. When the override is configured properly, SteamVR will have an additional tracker icon per each enabled controller.

Data Streaming

Now that the driver is set up, the HMD tracking will be overridden by tracking data from the mocap camera system, and you can integrate HMDs into the game engine through their own VR integration.

Streaming settings in Motive

First, make sure the streaming settings are configured in Motive for streaming out the data. For more information on streaming in Motive please visit our Streaming page:

• Broadcast Frame Data must be set to true.

• Local interface must be set to the desired IP address to stream the tracking data from.

• Streaming of Rigid Bodies must be set to True

• For wireless streaming, use Unicast streaming type.

Confirm the Connection

Once Motive is configured for streaming, launch SteamVR home to check the connection. If everything is setup correctly, you should be able to move around, or translate, within the scene freely. You may also need to check the ground plane to make sure it's well aligned.

If you experience any unexpected rotations in the view as you move your head, it could indicate that the HMD pivot point has not been calibrated properly. Please revisit the HMD Setup section and make sure the HMD Rigid Body pivot point is positioned and oriented at the expected pivot; which is at the root of nose with z-forward.

Unity SteamVR Setup

Notes for Unity users

Once this has been set up, the motion capture system will be used to drive the HMD in SteamVR. In Unity, you should be able to setup development for SteamVR applications and use our system.

Streaming Rigid Body/Skeleton data

This driver is designed for streaming of HMD and controller tracking data only. For streaming tracking data of other Rigid Body objects, you will need to use the corresponding plugins (Unreal Engine or Unity). In other words, the HMD tracking data will be streamed through the SteamVR using the driver you've installed, and all other tracking data will be streamed through the plugin.

Aligning world coordinates with the plugin

Client Origin

When using the OpenVR driver along with the OptiTrack Unity Plugin for streaming of tracking data other than the HMD, such as Rigid Bodies and/or Skeletons, it is important that the OptiTrack Client Origin object is located at the global origin without any rotations. In other words, the position must be set to (0,0,0) and the rotation must be set to (0,0,0) on the client origin. This is important because the driver does not use the OptiTrack Unity Plugin but instead streams the HMD tracking data directly onto SteamVR through a separate channel.

Overview

This page provides general instructions on how to use the eSync 2 for synchronizing external devices.

The eSync 2 is a synchronization hub that allows advanced users to integrate external systems into OptiTrack motion capture systems. With proper sync chain setups, you can have another (parent) system control the mocap system, or have the mocap system control other (child) systems, or both. Note that the setup may change depending on the type and number of the external devices as well as the characteristics of the communicated sync signals. Use this guide for understanding the general idea of how external devices are implemented and apply the knowledge for your needs.

External Device Synchronization

With the eSync 2, Prime series mocap systems can work together with other systems to perform precisely synchronized operations and data collections. This offers benefits in a wide range of applications. Reference video cameras, NI-DAQ devices, Force Plates, and recording triggers are examples of commonly synchronized external devices.

The eSync 2 synchronization hub has multiple sync input and output ports. In general, a parent device connects to the input ports for controlling the mocap system, and the child devices connect to output ports to be controlled by the mocap system. Once the devices are connected to the eSync 2, the input and output signal characteristics need to be specified and configured under the eSync 2's device properties in Motive.

Requirements

• Ethernet Camera System (PrimeX series or SlimX 13)

• The eSync 2

• External Devices (child / parent)

• Sync Cables: BNC or other sync cables with BNC adapters.

The eSync 2

Synchronization Setup

Step 1. Before setting up, draw out the schematic of which devices will be the parent or the child of the synchronization chain in respect to the mocap system.

Step 2. Connect the external devices

• Child Devices (e.g. Force Plates): Connect Output ports of the eSync 2 into sync input ports of the child devices

• Parent Device (e.g. Genlock): Connect the sync output of a parent device into one of the Input ports of the eSync 2. For integrating Genlock, VESA Stereo In, or SMPTE timecode signals, connect them to the corresponding labeled input ports of the eSync 2.

Step 3. Launch Motive. The eSync 2 should get listed under the Devices pane.

Step 4. [Motive] Open the Properties pane and select the eSync 2 in the Devices pane to access its properties.

Step 5. [Motive > Properties: eSync 2] Under the Sync Input Settings: Source section, use the drop-down menu to pick a desired sync source for the camera system to synchronize to. Read more under the Input Source Setup section of this page.

Step 6. [Motive > Properties: eSync 2] Configure the input divider/multiplier settings, and/or the clock frequency settings (for Internal Clock only), to set the camera rate. The final frame rate of the camera system will be displayed next to Camera Rate property or in the Devices pane.

Step 7. [Motive > Properties: eSync 2] Configure the Outputs. Output ports of the eSync 2 are used to tell connected child devices what Motive is doing. Read more under the Output Signal Setup section of this page.

Step 8. [Motive > Properties: eSync 2] If you wish to set up a recording trigger device, connect it to one of the input ports and designate the port under the Recording Trigger section of the eSync 2 properties. Read more under the Recording Trigger Setup section of this page.

Step 9. [Motive > Properties: eSync 2] Lastly, check the Monitor section and make sure all signals are detected properly.

Input Source Setup

Once you have connected the external devices to the eSync 2, the first step is to select and configure the sync source under th eSync 2 properties. The selected source will become the parent sync of both the camera system and other external devices. There are multiple sync source options to choose from under the drop-down menu. Ultimately, only one sync source will be selected and used to synchronize the cameras and subsequent child devices for any particular configuration.

Sync Input: Select the Sync Source

The first step is to define a parent sync source for the camera system. This is configured in the Sync Input → Source entry under the eSync 2 properties:

Internal Free Run

By default, the sync input source is set to Internal Free Run, meaning that the camera system is sampling at a frame rate defined in the Devices pane. In this mode, Prime series cameras are synchronized by communicating the time information with each other through the camera network itself using a high-precision algorithm for timing synchronization. This is the default synchronization protocol for Ethernet camera systems without an eSync 2.

Internal Clock

To use the internal clock of the eSync 2 as the parent sync source for both the camera system and the subsequent child devices, set the sync input source to Internal Clock. When selected, the clock frequency can be adjusted in Sync Input → Clock Freq (Hz) settings.

Input Signal

To use an external sync signal as the parent sync source, set the sync input source to the corresponding input port where the parent device is connected to. See the specifications for more details on each of the input ports.− Input ports (1-3): VIH(max): 3.3V− Isolated Input port: VIH(max): 12V− VESA Stereo Input port: VIH(max): 3.3V− Video Genlock In and SMPTE Timecode

Sync Input: Set the Input Trigger

Once the input source is set, next step is to define an appropriate trigger event. Under the Sync Input → Input Trigger option, pick a signal morphology (Either Edge, Rising Edge, or Falling Edge) for the desired trigger event. Note that the suitable event will vary depending on characteristics of the received signal and how you want the system to synchronize with it. The following diagrams show how the camera system responds to received signal triggers. When configured properly, the camera system will expose in respect to the sync signal from the parent device.

Rising Edge:

Every rising edge of the sync input signal defines either the start or the end of a frame, consecutively.

Falling Edge:

Every falling edge of the sync input signal defines either the start or the end of a frame, consecutively.

Either Edge:

Every rising or falling edge of the sync input signal defines either the start or the end of a frame, consecutively. When using both of the edges as the input trigger, the input signal must have 50% duty cycle for the cameras to synchronize properly.

Set the Input Divider/Multiplier

The frame rate of the camera system gets determined by the selected sync input source. When the frequency of the sync source is higher than the supported frame rate, input dividers and multiplier can be applied to adjust the signal frequency for synchronizing the camera system. The final framerate will be calculated and displayed at the bottom, Sync Input → Final Frame Rate, and you can monitor this rate while you apply the adjustments. When the customized sync configurations are applied at the end of the setup, the cameras will start to capture at this final frame rate.

Set Sync Offset

Advanced: Sync Input Trigger and Exposure Timing

Camera exposures are always positioned at the center of every frame periods, and the precise moment of the camera exposure does not exactly coincide with the trigger event. When synchronizing the camera exposure timing with the sync input signal triggers, make sure this gap is taken into account. To precisely align the input signal trigger with the exposure timing, an offset delay, in microseconds, of half of the frame period plus half of the camera exposure must be applied in the Sync Input → Sync Offset (us). The camera exposure is measured in microseconds on the Ethernet cameras.

Output Source Setup

The eSync 2 has total 4 output ports (3.3 V). If you want to setup the camera system to be a parent of other systems, connect the child devices into the Output ports of the eSync for receiving the reference sync signals. Once the devices are connected, you can configure the output signal source under the eSync 2 properties. Know what type of sync signals are expected by the child devices, and configure the sources accordingly so that appropriate signals are outputted.

The eSync 2 can output the following types of signals:

• Exposure Time

• Recording Gate

• Record Start/Stop Pulse

• Gated Exposure Time

• Gated Internal Clock

• Selected Sync

• Adjusted Sync

• Input signals: Relaying input signals.

  • Selected Sync: Raw input signal.

  • Adjusted Sync: Adjusted (offset, multiplier, and divider) signal.

Gated Output Signal (eSync 2):

The gated (while-recording) output signal from the eSync 2 is frame-synchronous with the recorded mocap data. In the live mode, the cameras are continuously shuttering and capturing frames at a defined frame rate. If the recording trigger is received in the middle of a frame period, the eSync waits until the next frame to start recording and asserting gated output signal. This mechanism ensures that the recorded mocap data and the gated output signals are precisely synchronized.

Exposure Time / Gated Exposure Time

Exposure Time/Gated Exposure Time output signals indicate when the cameras are exposing.

When the Output:Type is set to Exposure Time, a high voltage (3.3V) signal will be outputted from the corresponding output port whenever the camera system is exposing, or shuttering, in the Live Mode. The Gated Exposure Time signal works similarly, but the signal will be sent out only when Motive is recording.

Recording Gate & Recording Start/Stop Pulse

Recording gate/pulse output signals can be used to tell the child device when Motive is recording or not. When configured to Recording Gate, the eSync 2 will output a constant high voltage signal when Motive is recording. When configured to Recording Start/Stop Pulse, the sync hub will output a pulse signal when Motive either starts or stops recording.

Gated Internal Clock

When configured to Gated Internal Clock, the eSync 2 outputs its internal clock signal while Motive is recording. The internal clock signal has a 50% duty cycle with the signal frequency defined under the Sync Input → Clock Freq (Hz) section.

Using Internal Clock Signal to drive both the camera system and external devices

To achieve per-frame synchronization between the camera system and an external device (e.g. force plates, NI-DAQ), the internal clock signal from the eSync 2 can be used to drive both the camera system as well as the external device. This is possible only if the external device has the capability of receiving external clock signal. When the external system runs at a higher sampling rate, a divisor or a multiplier must be applied to the clock signal to achieve the desired framerate on the camera system. Here, please note that depending on the applied divisor/multiplier, the alignment of the outputted signal may vary. The exposure timing of the camera system will always be aligned at the center of the divided or multiplied signal, and whether the exposure timing aligns with the rising edge or falling edge of the output signal may vary depending on the applied divisor. Please see the below image:

Hardware Recording Trigger Setup

With the eSync 2, external triggering devices (e.g. remote start/stop button) can integrate into the camera system and set to trigger the recording start and stop events in Motive. Such devices will connect to input ports of the eSync 2 and configured under the Record Triggering section of the eSync 2 properties.

By default, the remote trigger source is set to Software, which is the record start/stop button click events in Motive. Set the trigger source to the corresponding input port and select an appropriate trigger edge when an external trigger source (Trigger Source → isolated or input) is used. Available trigger options include Rising Edge, Falling Edge, High Gated, or Low Gated. The appropriate trigger option will depend on the signal morphology of the external trigger. After the trigger setting have been defined, press the recording button in advance. It sets Motive into a standby mode until the trigger signal is detected through the eSync 2. When the trigger signal is detected, Motive will start the actual recording. The recording will be stopped and return to the 'armed' state when the second trigger signal, or the falling edge of the gated signal, is detected.

Note: For capturing multiple recordings via recording trigger, only the first TAK will contain the 3D data. For the subsequent TAKs_, the 3D data must be reconstructed through the_ post-processing reconstruction pipeline.

Steps

1. Open the Devices pane and the Properties pane to access the eSync 2 properties.

2. Under the Record Triggering section, set the source to the respective input port where the trigger signal is inputted.

3. Choose an appropriate trigger option, depending on the morphology of the trigger signal.

4. Press the record button in Motive, which prepares Motive for recording. At this stage, Motive awaits for an incoming trigger signal.

5. When the first trigger is detected, Motive starts recording.

6. When the second trigger is detected, Motive stops recording and awaits for next trigger for repeated recordings. For High Gated and Low Gated trigger options, Motive will record during respective gated windows.

7. Once all the recording is finished, press the stop button to disarm Motive.

Troubleshooting

This page provides instructions on how to set up and use the OptiTrack active marker solution.

Overview

The OptiTrack Active Tracking solution allows synchronized tracking of active LED markers using an OptiTrack camera system. Consisting of the Base Station and the users choice Active Tags that can be integrated in to any object and/or the "Active Puck" which can act as its own single rigid body.

Connected to the camera system the Base Station emits RF signals to the active markers, allowing precise synchronization between camera exposure and illumination of the LEDs. Each active marker is now uniquely labeled in Motive software, allowing more stable rigid body tracking since active markers will never be mislabeled and unique marker placements are no longer be required for distinguishing multiple rigid bodies.

Hardware Setup

Required Component

BaseStation

Sends out radio frequency signals for synchronizing the active markers.

• Powered by PoE, connected via Ethernet cable.

• Must be connected to one of the switches in the camera network.

Active Marker Options

Active Tag

• Connects to a USB power source and illuminates the active LEDs.

• Receives RF signals from the Base Station and correspondingly synchronizes illumination of the connected active LED markers.

• Emits 850 nm IR light.

• 4 active LEDs in each bundle and up to two bundles can be connected to each Tag.

• (8 Active LEDs (4(LEDs/set) x 2 set) per Tag)

• Size: 5 mm (T1 ¾) Plastic Package, half angle ±65°, typ. 12 mW/sr at 100mA

Active Pucks

An active tag self-contained into a trackable object, providing information with 6 DoF for any arbitrary object that it's attached to. Carries a factory installed Active Tag with 8 LEDs and a rechargeable battery with up to 10-hours of run time on a single charge.

Wiring the Components

Camera System

BaseStation

• Connects to one of the PoE switches within the camera network.

• For best performance, place the base station near the center of your tracking space, with unobstructed lines of sight to the areas where your Active Tags will be located during use. Although the wireless signal is capable of traveling through many types of obstructions, there still exists the possibility of reduced range as a result of interference, particularly from metal and other dense materials.

• Do not place external electromagnetic or radiofrequency devices near the Base Station.

• When Base Station is working properly, the LED closest to the antenna should blink green when Motive is running.

Tag Setup

• Connect two sets of active markers (4 LEDs in each set) into a Tag.

• Connect the battery and/or a micro USB cable to power the Tag. The Tag takes 3.3V ~ 5.0V of inputs from the micro USB cable. For powering through the battery, use only the batteries that are supplied by us. To recharge the battery, have the battery connected to the Tag and then connect the micro USB cable.

• To initialize the Tag, press on the power switch once. Be careful not to hold down on the power switch for more than a second, because it will trigger to start the device in the firmware update (DFU) mode. If it initializes in the DFU mode, which is indicated by two orange LEDs, just power off and restart the Tag. To power off the Tag, hold down on the power switch until the status LEDs go dark.

• Once powered, you should be able to see the illumination of IR LEDs from the 2D reference camera view.

Puck Setup

• Press the power button for 1~2 seconds and release. The top-left LED will illuminate in orange while it initializes. Once it initializes the bottom LED will light up green if it has made a successful connection with the base station. Then the top-left LED will start blinking in green indicating that the sync packets are being received.

Motive Settings

Active Patten Depth

Settings → Live Pipeline → Solver Tab with Default value = 12

This adjusts the complexity of the illumination patterns produced by active markers. In most applications, the default value can be used for quality tracking results. If a high number of rigid bodies are tracked simultaneously, this value can be increased allowing for more combinations of the illumination patterns on each marker. If this value is set too low, duplicate active IDs can be produced, should this error appear increase the value of this setting.

Minimum Active Count

Settings → Live Pipeline → Solver Tab with Default value = 3

Setting the number of rays required to establish the active ID for each on frame of an active marker cycle. If this value is increased, and active makers become occluded it may take longer for active markers to be reestablished in the Motive view. The majority of applications will not need to alter this setting

Active Marker Color

Settings → Views → 3D Tab with Default color = blue

The color assigned to this setting will be used to indicate and distinguish active and passive markers seen in the viewer pane of Motive.

Camera Settings

For tracking of the active LED markers, the following camera settings may need to be adjusted for best tracking results:

Camera Exposure

For tracking the active markers, set the camera exposures a bit higher compared to when tracking passive markers. This allows the cameras to better detect the active markers. The optimal value will vary depending on the camera system setups, but in general, you would want to set the camera exposure between 400 ~ 750, microseconds.

IR LEDs

Active Markers in Motive

Active Labels

Labels in Recorded 3D Data

Unlabeled Markers

In recorded 3D data, the labels of the unlabeled active markers will still indicate that it is an active marker. As shown in the image below, there will be Active prefix assigned in addition to the active ID to indicate that it is an active marker. This applies only to individual active markers that are not auto-labeled. Markers that are auto-labeled using a trackable model will be assigned with a respective label.

Auto-labeled Markers

When a trackable asset (e.g. rigid body) is defined using active markers, it's active ID information gets stored in the asset along with marker positions. When auto-labeling the markers in the space, the trackable asset will additionally search for reconstructions with matching active ID, in addition to the marker arrangements, to auto-label a set of markers. This can add additional guard to the auto-labeler and prevents and mis-labeling errors.

Rigid Body Definition

Rigid body definitions created from actively labeled reconstructions will search for respective marker IDs in order to solve the rigid body. This gives a huge benefit because the active markers can be placed in perfectly symmetrical marker arrangements among multiple rigid bodies and not run into labeling swaps. With active markers, only the 3D reconstructions with active IDs stored under the corresponding rigid body definition will contribute to the solve.

Rigid Body Properties

If a rigid body was created from actively labeled reconstructions, the corresponding Active ID gets saved under the corresponding rigid body properties. In order for the rigid body to be tracked, the reconstructions with matching marker IDs in addition to matching marker placements must be tracked in the volume. If the active ID is set to 0, it means no particular marker ID is given to the rigid body definition and any reconstructions can contribute to the solve.

Troubleshooting