Overview

The new Continuous Calibration feature ensures your system always remains optimally calibrated, requiring no user intervention to maintain the tracking quality. It uses highly sophisticated algorithms to evaluate the quality of the calibration and the triangulated marker positions. Whenever the tracking accuracy degrades, Motive will automatically detect and update the calibration and provide the most globally optimized tracking system.

Key Features

• Ease of use. This feature provides much easier user experience because the capture volume will not have to be re-calibrated as often, which will save a lot of time. You can simply enable this feature and have Motive maintain the calibration quality.

• Optimal tracking quality. Always maintains the best tracking solution for live camera systems. This ensures that your captured sessions retain the highest quality calibration. If the system receives inadequate information from the environment, the calibration with not update and your system never degrades based on sporadic or spurious data. A moderate increase in the number of real optical tracking markers in the volume and an increase in camera overlap improves the likelihood of a higher quality update.

• Works with all camera types. Continuous calibration works with all OptiTrack camera models, including the V120 Tracking bars, the Flex series camera systems, and the Prime series camera systems as well as the Slim13E camera systems for active marker tracking.

Requirements

For continuous calibration to work as expected, the following criteria must be met:

• Live Mode Only. Continuous calibration only works in Live mode. It will not be active during Recording or while in Edit mode.

• Markers Must Be Tracked. Continuous calibration looks at tracked reconstructions to assess and update the calibration. Therefore, at least some number of markers must be tracked within the volume.

• Majority of Cameras Must See Markers. A majority of cameras in a volume needs to receive some tracking data within a portion of their field of view in order to initiate the calibration process. Because of this, traditional perimeter camera systems typically work the best. Each camera should additionally see at least 4 markers for optimal calibration.

Modes

There are two different modes of continuous calibration: Continuous and Continuous + Bumped.

Continuous

The Continuous mode is used to maintain the calibration quality, and this should be utilized in most cases. In this mode, Motive monitors how well the tracked rays converge onto tracked markers, and it updates the calibration so corresponding tracked rays converge more precisely. This mode is capable of correcting minor degradations that result from ambient influences, such as the thermal expansions on the camera mounting structure.

Continuous + Bumped

The Continuous + Bumped mode combines the continuous calibration refinement described above with the ability to resolve and repair cameras that have been bumped and are no longer contributing to 3D reconstruction. By utilizing this feature, the bumped camera will automatically resolve and be reintroduced into the calibration without requiring the user to perform a manual calibration. For just maintaining overall calibration quality, the Continuous mode should be used instead of the Continuous + Bumped mode.

How to Use

The continuous calibration can be enabled or disabled in the Application Settings pane under the reconstruction tab. Set the Continuous Calibration setting to Continuous, or Continuous + Bumped to allow the feature to update the system calibration.

Continuous mode

1. Under the Application Settings -> Reconstruction tab, set the continuous calibration to Continuous.

2. Once enabled, Motive continuously monitors the residual values in captured marker reconstructions. When the residual value increases, Motive will start sampling data for continuous calibration.

3. Make sure at least some number of markers are being tracked in the volume.

4. When a sufficient number of samples have been collected, Motive updates the calibration.

5. When successfully updated, the result will be notified on the Status Log pane.

Continuous + Bumped Camera mode

1. When a camera is bumped and its orientation have been shifted greatly, the affected camera will no longer properly contribute to the tracking. As a result, there will be a lot of untracked rays generated by this camera.

2. Under the Application Settings -> Reconstruction tab, set the continuous calibration to Continuous + Bumped Camera.

3. Make sure there are one or more 3D reconstructed markers in motion within the field of view of the bumped camera.

4. When a sufficient number of samples have been collected, Motive updates the calibration and the bumped camera will be corrected and the system calibration will be updated.

5. Check the masking from the 2D Camera Previews. The masks may not be properly placed over the extraneous reflections due to the updated calibration. If so, simply re-mask the extraneous reflections. See: Masking

6. (Optional) If needed, export the updated calibration into a CAL file.

Anchor Markers

Anchor markers can be set up in Motive to further improve continuous calibration. When properly configured, anchor markers improve continuous calibration updates, especially on systems that consist of multiple sets of cameras that are separated into different tracking areas, by obstructions or walls, without camera view overlap. It also provides extra assurance that the global origin will not shift during each update; although the continuous calibration feature itself already checks for this.

Anchor Marker Setup

Follow the below steps for setting up the active anchor marker in Motive:

Adding Anchor Markers in Motive

1. First, make sure the entire camera volume is fully calibrated and prepared for marker tracking.

2. Place any number of markers in the volume to assign them as the anchor markers.

3. Make sure these markers are securely fixed in place within the volume. It's important that the distances between these markers do not change throughout the continuous calibration updates.

4. In the 3D viewport, select the markers that are going to be assigned as anchors.

5. Right-click on the marker to bring up the context menu. Then go to Anchor Markers → Add Selected Markers.

6. Once markers are added as anchor markers, magenta spheres will appear around the markers indicating the anchors have been set.

7. Add more anchors as needed, again, it's important that these anchor markers do not move throughout the tracking. Also when the anchor markers need to be reset, whether if the marker was displaced, you can clear the anchor markers and reassign them.

OptiTrack motion capture systems can use both passive and active markers as indicators for 3D position and orientation. An appropriate marker setup is essential for both tracking the quality and reliability of captured data. All markers must be properly placed and must remain securely attached to surfaces throughout the capture. If any markers are taken off or moved, they will become unlabeled from the Marker Set and will stop contributing to the tracking of the attached object. In addition to marker placements, marker counts and specifications (sizes, circularity, and reflectivity) also influence the tracking quality. Passive (retroreflective) markers need to have well-maintained retroreflective surfaces in order to fully reflect the IR light back to the camera. Active (LED) markers must be properly configured and synchronized with the system.

Retroreflective Markers

OptiTrack cameras track any surfaces covered with retroreflective material, which is designed to reflect incoming light back to its source. IR light emitted from the camera is reflected by passive markers and detected by the camera’s sensor. Then, the captured reflections are used to calculate the 2D marker position, which is used by Motive to compute 3D position through reconstruction. Depending on which markers are used (size, shape, etc.) you may want to adjust the camera filter parameters from the Live Pipeline settings in Application Settings.

Marker Size

The size of markers affects visibility. Larger markers stand out in the camera view and can be tracked at longer distances, but they are less suitable for tracking fine movements or small objects. In contrast, smaller markers are beneficial for precise tracking (e.g. facial tracking and microvolume tracking), but have difficulty being tracked at long distances or in restricted settings and are more likely to be occluded during capture. Choose appropriate marker sizes to optimize the tracking for different applications.

Circularity

If you wish to track non-spherical retroreflective surfaces, lower the Circularity value in 2D object filter in the application settings. This adjusts the circle filter threshold and non-circular reflections can also be considered as markers. However, keep in mind that this will lower the filtering threshold for extraneous reflections as well. If you wish to track non-spherical retroreflective surfaces, lower the Circularity value from the cameras tab in the application settings.

Worn markers

All markers need to have a well-maintained retroreflective surface. Every marker must satisfy the brightness Threshold defined from the camera properties to be recognized in Motive. Worn markers with damaged retroreflective surfaces will appear to a dimmer image in the camera view, and the tracking may be limited.

Custom Markers

OptiTrack cameras can track any surface covered with retro-reflective material. For best results, markers should be completely spherical with a smooth and clean surface. Hemispherical or flat markers (e.g. retro-reflective tape on a flat surface) can be tracked effectively from straight on, but when viewed from an angle, they will produce a less accurate centroid calculation. Hence, non-spherical markers will have a less trackable range of motion when compared to tracking fully spherical markers.

Active Markers

OptiTrack Active Markers

OptiTrack's active solution provides advanced tracking of IR LED markers to accomplish the best tracking results. This allows each marker to be labeled individually. Please refer to the Active Marker Tracking page for more information.

Custom Active Markers

Active (LED) markers can also be tracked with OptiTrack cameras when properly configured. We recommend using OptiTrack’s Ultra Wide Angle 850nm LEDs for active LED tracking applications. If third-party LEDs are used, their illumination wavelength should be at 850nm for best results. Otherwise, light from the LED will be filtered by the band-pass filter.

If your application requires tracking LEDs outside of the 850nm wavelength, the OptiTrack camera should not be equipped with the 850nm band-pass filter, as it will cut off any illumination above or below the 850nm wavelength. An alternative solution is to use the 700nm short-pass filter (for passing illumination in the visible spectrum) and the 800nm long-pass filter (for passing illumination in the IR spectrum). If the camera is not equipped with the filter, the Filter Switcher add-on is available for purchase at our webstore. There are also other important considerations when incorporating active markers in Motive:

• Place a spherical diffuser around each LED marker to increase the illumination angle. This will improve the tracking since bare LED bulbs have limited illumination angles due to their narrow beamwidth. Even with wide-angle LEDs, the lighting coverage of bare LED bulbs will be insufficient for the cameras to track the markers at an angle.

• If an LED-based marker system will be strobed (to increase range, offset groups of LEDs, etc.), it is important to synchronize their strobes with the camera system. If you require a LED synchronization solution, please contact one of our Sales Engineers to learn more about OptiTrack’s RF-based LED synchronizer.

• Many applications that require active LEDs for tracking (e.g. very large setups with long distances from a camera to a marker) will also require active LEDs during calibration to ensure sufficient overlap in-camera samples during the wanding process. We recommend using OptiTrack’s Wireless Active LED Calibration Wand for best results in these types of applications. Please contact one of our Sales Engineers to order this calibration accessory.

Marker Placement

Proper marker placement is vital for quality of motion capture data because each marker on a tracked subject is used as indicators for both position and orientation. When an asset (a Rigid Body or Skeleton) is created in Motive, its unique spatial relationships of the markers are calibrated and recorded. Then, the recorded information is used to recognize the markers in the corresponding asset during the auto-labeling process. For best tracking results, when multiple subjects with a similar shape are involved in the capture, it is necessary to offset their marker placements to introduce the asymmetry and avoid the congruency.

Read more about marker placements from the Rigid Body Tracking page and the Skeleton Tracking page.

Marker Bases and Adhesives

Prepare the markers and attach them on the subject, a Rigid Body or a person. Minimize extraneous reflections by covering shiny surfaces with non-reflective tapes. Then, securely attach the markers to the subject using enough adhesives suitable for the surface. There are various types of adhesives and marker bases available on our webstore for attaching the marker: Acrylic, Rubber, Skin adhesive, and Velcro. Multiple types of marker bases are also available: carbon fiber filled bases, Velcro bases, and snap-on plastic bases.

Installation

Host PC Requirements

Required PC specifications may vary depending on the size of the camera system. Generally, you will be required to use the recommended specs with a system with more than 24 cameras.

Download

To install Motive, you must first download the Motive installer from our website. Follow the Downloads link under the Support page (http://optitrack.com/downloads/), and you will be able to find the newest version of Motive or the previous releases if needed. Both Motive: Body and Motive: Tracker shares same software installer.

Installation Steps

1. Run the Installer

When the download is complete, run the installer to initiate the installation process.

2. Install the USB Driver and Dependencies

If you are installing Motive for the first time, it will prompt you to install the OptiTrack USB Driver. This driver is required for all OptiTrack USB devices including the Hardware Key. You may also need to install other dependencies such as the C++ redistributable and DirectX. After all dependencies have been installed, continue onto installing the Motive.

3. Install Motive

Follow the installation prompts and install Motive in your desired file directory. We recommend installing the software in the default directory, C:\Program File\OptiTrack\Motive.

4. OptiTrack Peripheral Module

At the Custom Setup section of the installation process, you will be asked to choose whether to install the Peripheral Devices along with Motive. If you plan to use force plate, NI-DAQ, or EMG devices along with motion capture systems, then make sure the Peripheral Device is installed. If you are not going to be using these devices, you may skip to the next step.

5. Finish Installation

After you have completed all steps above Motive will be installed. If you want to use additional plugins, visit the downloads page

Host PC Setup

Firewall / Anti-Virus

• Make sure all anti-virus software on the Host PC is allowing Motive.

• For Ethernet cameras, make sure the windows' firewall is configured to allow the camera network to be recognized. Disabling them entirely is another option.

High-Performance

Windows power saving mode limits CPU usage. In order to best utilize Motive, set this mode to the High Performance mode and remove the limitations. You can configure the High Performance Mode from Control Panel → Hardware and Sound → Power Options as shown in the image below.

Graphics Card Settings

This is only for computers with integrated graphics.

For computers with integrated graphics, please make sure Motive is set to run on the dedicated graphics card. If the host computer has integrated graphics on the CPU, the PC may switch to using integrated graphics when the computer goes to sleep mode, and when this happens, the viewport may go unresponsive when it exits out of the sleep mode. If you have integrated graphics on the computer, go to the Graphics Settings on Windows, and browse Motive to set it as high-performance graphics.

License Activation

Once you have installed Motive, the next step is to activate the software using the provided license information and a USB Security Key. Motive activation requires a valid Motive 3.0 license, a USB Security Key, and a computer with access to the Internet.

Hardware Key

For Motive 2.x, a USB Hardware Key is required to use the camera system. The Hardware Key stores licensing information and allows you to use a single license to perform different tasks using different computers. Hardware keys are purchased separately. For more information, please see the following page:

• https://optitrack.com/accessories/license-keys/

License Types

There are five different types of Motive licenses: Motive:Body-Unlimited, Motive:Body, Motive:Tracker, Motive:Edit-Unlimited, and Motive:Edit. Each license unlocks different features in the software depending on the use case that the license is intended to facilitate.

• The Motive:Body and Motive:Body-Unlimited licenses are intended for either small (up to 3) or large-scale Skeleton tracking applications.

• The Motive:Tracker license is intended for real-time Rigid Body tracking applications.

• The Motive:Edit and Motive:Edit Unlimited licenses are intended for users modifying data after it has been captured already

For more information on different types of Motive licenses, check the software comparison table on our website or in the table below.

Activation Steps

Step 1. Launch Motive

First, launch Motive.

Step 2. Activate

The Motive splash screen will pop up and it will indicate that the license is not found. Click and open the license tool and fill out the following fields using provided license information. You will need the License Serial Number and License Hash from your order invoice and the Hardware Key Serial Number indicated on the USB security key or the hardware key. Once you have entered all the information, click Activate. If you have already activated the license before on another machine, make sure the same name is entered when activating.

Step 3. License File

If Motive is activated properly, license files will be placed in the license folder. This folder can be accessed from the splash screen or by navigating to Start Menu → All Programs → OptiTrack → Motive → OptiTrack License Folder.

License Folder: C:\ProgramData\OptiTrack\License

Step 4. Hardware Key

If not already done, insert the corresponding Hardware Key that was used to activate the license. The matching security key must be connected to the computer in order to use Motive.

About Motive

You can also check the status of the activated license from the About Motive pop-up. This can be accessed in the splash screen when it fails to detect a valid license, or it can be accessed from the Help``→``About Motive menu in Motive.

Using Activated Software on a Different Computer

OptiTrack software can be used on a new computer by reactivating the license, using the same license information. When reactivating, make sure to enter the same name information as before. After the license has been reactivated, the corresponding USB Hardware Key needs to be inserted into the PC in order to verify and run the software.

Another method of using the license is by copying the license file from the old computer to the new computer. The license file can be found in the OptiTrack License folder which can be accessed through the Motive Splash Screen or top Help menu in Motive.

More Questions?

General Questions

For more information on licensing of Motive, refer to the Licensing FAQs from the OptiTrack website:

• http://optitrack.com/support/faq/licensing.html

For more questions, contact our Support:

• http://optitrack.com/support/

• When contacting support, please attach the license data (TXT) file exported from the About Motive panel as a reference.

Troubleshooting: Licensing

Before diving into specific details, let’s begin with a brief overview of Motive. If you are new to using Motive, we recommend you to read through this page and learn about the basic tools, configurations and navigation controls, as well as instructions on managing capture files.

File Management

In Motive, the recorded mocap data is stored in a file format called Take (TAK), and multiple Take files can be grouped within a session folder. The Data pane is the primary interface for managing capture files in Motive. This pane can be accessed from the icon on the main Toolbar, and it contains a list of session folders and the corresponding Take files that are recorded or loaded in Motive.

Motive will save and load Motive-specific file formats including the Take files (TAK), camera calibration files (CAL), and Motive user profiles (MOTIVE) that can contain most of the software settings as well as asset definitions for Skeletons and Rigid Body objects. Asset definitions are related to trackable objects in Motive which will be explained further in the Rigid Body Tracking and Skeleton Tracking page.

Take File (.TAK)

Motive file management is centered on the Take (TAK) file. A TAK file is a single motion capture recording (aka 'take' or 'trial'), which contains all the information necessary to recreate the entire capture from the file, including camera calibration, camera 2D data, reconstructed and labeled 3D data, data edits, solved joint angle data, tracking models (Skeletons, Rigid Bodies), and any additional device data (audio, force plate, etc). A Motive Take (TAK) file is a completely self-contained motion capture recording, and it can be opened by another copy of Motive on another system.

Session Folders

A Session is a file folder that allows the user to organize multiple similar takes (e.g. Monday, Tuesday, Wednesday, or StaticTrials, WalkingTrials, RunningTrials, etc). Whether you are planning the day's shoot or incorporating a group of Takes mid-project, creating session folders can help manage complex sets of data. In the Data pane, you can import session folders that contain multiple Takes or create a new folder to start a new capture session. For a most efficient workflow, plan the mocap session before the capture and organize a list of captures (shots) that need to be completed. Type Take names in a spreadsheet or a text file, and Copy and paste the list, which will automatically create empty Takes (shot list) with corresponding names from the pasted list.

Motive User Profile (.MOTIVE)

Software configurations are saved onto the motive profile (*.motive) files. In the motive profile, all of the application-related configurations, lists of assets, and the loaded session folders are saved and preserved. You can export and import the profiles to easily maintain the same software configurations each time Motive is launched.

All of the currently configured software settings will get saved onto the C:\ProgramData\OptiTrack\MotiveProfile.motive file periodically throughout capture and when closing out of Motive. This file is the default application profile, and it gets loaded back when Motive is launched again. This allows all of the configurations to be persisted in between different sessions of Motive. If you wish to revert all of the settings to its factory default, use the Reset Application Settings button under the Edit tab of the main command bar.

Motive profiles can also be exported and imported from the File menu of the main command bar. Using the profiles, you can easily transfer and persist Motive configurations among different instances and different computers.

The followings are saved on application profile:

• Application Settings

• Live Pipeline Settings

• Streaming Settings

• Synchronization Settings

• Export Settings

• Rigid Body & Skeleton assets

• Rigid Body & Skeleton settings

• Labeling settings

• Hotkey configurations

Calibration files (CAL

A calibration file is a standalone file that contains all of the required information to completely restore a calibrated camera volume, including positions and orientations of each camera, lens distortion parameters, and the camera settings. After a camera system is calibrated, CAL file can be exported and imported back again onto Motive when needed. Thus, it is recommended to save out the camera calibration file after each round of calibration.

Please note that reconstruction settings also get stored in the calibration file; just like how it gets stored in the MOTIVE profile. If the calibration file is imported after the profile file was loaded, it may overwrite the previous reconstruction settings as it gets imported.

Note that this file is reliable only if the camera setup has remained unchanged since the calibration. Read more from Calibration page.

The followings are saved on application profile:

• Reconstruction settings

• Camera settings

• Position and orientation of the cameras

• Location of the global origin

• Lens distortion of each camera

Viewports

In Motive, the main viewport is fixed at the center of the UI and is used for monitoring the 2D or 3D capture data in both live capture and playback of recorded data. The viewport can be set to either perspective view or camera view. The Perspective View mode shows the reconstructed 3D data within the calibrated 3D space, and the Camera View mode shows 2D images from each camera in the setup. These modes can be selected from the drop-down menu at the top-right corner, and both of these views are essential for assessing and monitoring the tracking data.

Perspective View - 3D

• Use the dropdown menu at the top-left corner to switch into the Perspective View mode. You can also use the number 1 hotkey while on a viewport.

• Used to look through the reconstructed 3D representation of the capture, analyze marker positions, rays used in reconstruction, etc.

• The context menu in the Perspective View allows you to access more options related to the markers and assets in 3D tracking data.

Camera Preview - 2D

• Use the dropdown menu at the top-left corner to switch into the Camera View mode. You can also use the number 2 hotkey while on a viewport.

• Each camera’s view can be accessed from the Camera Preview pane. It displays the images that are being transmitted from each camera. The image processing modes are displayed, including grayscale and object.

• Detected IR lights and/or reflections are also shown in this pane. Only the IR lights that satisfy the object filters get considered as markers.

• From the Camera Preview pane, you can mask certain pixel regions to exclude them from the process.

Additional Viewports

• When needed, the viewport can be split into 4 different smaller views. This can be selected from the menu at the top-right corner of the viewport. You can use the hotkeys (Shift + 4) to do this also.

Basic Navigation Controls

View Port Mouse Control

Mouse controls in Motive can be customized from the application settings panel to match your preference. Motive also includes a variety of common mouse control presets so that any new users can easily start controlling Motive. Available preset control profiles include Motive, Blade, Maya, and Visual3D. The following table shows a few basics actions that are commonly used for navigating the viewports in Motive.

Hotkeys

Using the Hotkeys can speed up workflows. Most of the default hotkeys are listed on the Motive Hotkeys page. When needed, the hotkeys can also be customized from the application settings panel which can be accessed under the Edit tab. Various actions can be assigned with a custom hotkey using the Hotkey Editor.

Control Deck

The Control Deck is always docked at the bottom of Motive, and it provides both recording and navigation controls over Motive's two primary operating modes: Live mode and Edit mode.

Live Mode and Edit Mode

In the Live Mode, all cameras are active and the system is processing camera data. If the mocap system is already calibrated, Motive is live-reconstructing 2D camera data into labeled and unlabeled 3D trajectories (markers) in real-time. The live tracking data can be streamed to other applications using the data streaming tools or the NatNet SDK. Also, in Live mode, the system is ready for recording and corresponding capture controls will be available in the Control Deck.

In the Edit Mode, the cameras are not active, and Motive is processing loaded Take file (pre-recorded data). The playback controls will be available in the control deck, and the small timeline will appear at the top of the control deck for scrubbing through the recorded frames. In this mode, you can review the recorded 3D data from the TAK and make post-processing edits and/or manually assign marker labels to the recorded trajectories before exporting out the tracking data. Also, when needed, you can switch to the 2D mode, and view the real-time reconstructed 3D data to understand how the 3D data was obtained and perform post-processing reconstruction pipeline to re-obtain a new set of 3D data.

Graph View pane

The Graph View pane is used for plotting live or recorded channel data in Motive. For example, 3D coordinates of the reconstructed markers, 3D positions and orientations of Rigid Body assets, force plate data, analog data from data acquisition devices, and more can be plotted on this pane. You can switch between existing layouts or create a custom layout for plotting specific channel data.

Basic navigation controls are highlighted below. For more information, read through the Graph View pane page.

Basic Navigation Controls

On the Graph

Navigate Frames (Alt + Left-click + Drag)

Alt + left-click on the graph and drag the mouse left and right to navigate through the recorded frames. You can do the same with the mouse scroll as well.

Panning (Scroll-click + Drag)

Scroll-click and drag to pan the view vertically and horizontally throughout plotted graphs. Dragging the cursor left and right will pan the view along the horizontal axis for all of the graphs. When navigating vertically, scroll-click on a graph and drag up and down to pan vertically for the specific graph.

Zooming (Right-click + Drag)

Selecting Frame Range (Left-click + Drag)

The frame range selection is used when making post-processing edits on specific ranges of the recorded frames. Select a specific range by left-clicking and dragging the mouse left and right, and the selected frame ranges will be highlighted in yellow. You can also select more than one frame ranges by shift-selecting multiple ranges.

On the Navigation Bar

Navigate Frames (Left-click)

Left-click and drag on the nav bar to scrub through the recorded frames. You can do the same with the mouse scroll as well.

Pan View Range

Scroll-click and drag to pan the view range range.

Frame Range Zoom

Zoom into a frame range by re-sizing the scope range using the navigation bar handles. You can also easily do this by Alt + right-clicking on the graph and selecting a specific range to zoom into.

Navigation Bar

Working Range / Playback range

The working range (also called the playback range) is both the view range and the playback range of a corresponding Take in Edit mode. Only within the working frame range, recorded tracking data will be played back and shown on the graphs. This range can also be used to output a specific frame ranges when exporting tracking data from Motive.

The working range can be set from different places:

• In the navigation bar of the Graph View pane, you can drag the handles on the scrubber to set the working range.

• You can also use the navigation controls on the Graph View pane to zoom in or zoom out on the frame ranges to set the working range.

• Start and end frames of a working range can also be set from the Control Deck when in the Edit mode.

Selection Range

The selection range is used to apply post-processing edits only onto a specific frame range of a Take. Selected frame range will be highlighted in yellow on both Graph View pane as well as Timeline pane.

Gap indication

When playing back a recorded capture, the red colors on the navigation bar indicate the amount of occlusions from labeled markers. Brighter red means that there are more markers with labeling gaps.

Application Settings

This pane is used for configuring application-wide settings, which include startup configurations, display options for both 2D and 3D viewports, settings for asset creation, and most importantly, live-pipeline parameters for the Solver and the 2D Filter settings for the cameras. The Cameras tab includes the 2D filter settings that basically determine which reflections gets considered as marker reflections on the camera views, and the Solver setting determines which 3D markers get reconstructed in the scene from a group of marker reflections from all of the cameras. References for the available settings are documented in the Application Settings page.

Solver Settings

Under the Solver tab, you can configure a real-time solver engine. These settings, including the trajectorizer settings, are one of the most important settings in Motive. These settings determine how 3D coordinates are acquired from the captured 2D camera images and how they are used for tracking Rigid Bodies and Skeletons. Thus, understanding these settings is very important for optimizing the system for the best tracking results.

Camera Settings

Under the Camera tab, you can configure the 2D Camera filter settings (circularity filter and size filter) as well as other display options for the cameras. The 2D Camera filter setting is one of the key settings for optimizing the capture. For most applications, the default settings work well, but it is still beneficial to understand some of the core settings in order for more efficient control over the camera system.

For more information, read through the Application Settings: Live Pipeline page and the Reconstruction and 2D Mode

Layouts

The UI layout in Motive is customizable. All panes can be docked and undocked from the UI. Each pane can be positioned and organized by drag-and-drop using the on-screen docking indicators. Panes may float, dock, or stack. When stacked together, they form a tabbed window for quickly cycling through. Layouts in Motive can be saved and loaded, allowing a user to switch quickly between default and custom configurations suitable for different needs. Motive has preset layouts for Calibration, Creating a Skeleton, Capturing (Record), and Editing workflows. Custom layouts can be created, saved, and set as default from the Main Menu -> 'Layout' menu item. Quickly restore a particular layout from the Layout menu, the Layout Dropdown at the top right of the Main Menu, or via HotKeys.

This page covers basic types of trackable assets in Motive. The assets in Motive are used for both tracking of the objects and labeling of 3D markers in Motive, and they are managed under the Assets pane which can be opened by clicking on the icon. Each type of asset is further explained in the related pages.

Overview

Once Motive is prepared, the next step is to place markers on the subject and create corresponding assets. There are three different types of assets in Motive:

• Marker Set

• Rigid Body

• Skeleton

For each Take, involved assets are displayed in the Assets pane, and the related properties show up at the Properties pane when an asset is selected within Motive.

The Marker Set is a list of marker labels that are used to annotate reconstructed markers. Marker Sets should only be used in situations where it is not possible to define a Rigid Body or Skeleton. In this case, the user will manually label markers in post-processing. When doing so, having a defined set of labels (Marker Set) makes this process much easier. Marker Sets within a Take will be listed in the Labels pane, and each label can be assigned through the Labeling process.

Rigid body and Skeleton assets are the Tracking Models. Rigid bodies are created for tracking rigid objects, and Skeleton assets are created for tracking human motions. These assets automatically apply a set of predefined labels to reconstructed trajectories using Motive's tracking and labeling algorithms, and Motive uses the labeled markers to calculate the position and orientation of the Rigid Body or Skeleton Segment. Both Rigid Body and Skeleton tracking data can be sent to other pipelines (e.g. animations and biomechanics) for extended applications. If new Skeletons or Rigid Bodies are created during post-processing, the take will need to be reconstructed and auto-labeled in order to apply the changes to the 3D data.

Copying Assets

The Assets pane lists out all assets that are available in the current capture. You can easily copy these assets onto other recorded Take(s) or to the live capture by doing the following:

Copying Assets to a Recorded _Take_

In order to copy and paste assets onto another Take, right-click on the desired Take to bring up the context menu and choose Copy Assets to Takes. This will bring up a dialog window for selecting which assets to move.

Copying Assets to Multiple Recorded _Take(s)_

If you wish to copy assets to multiple Takes, select multiple takes from the Data pane until the desired takes are all highlighted. Repeat the steps you took above for copying a single Take by right-clicking on any of the selected Takes. This should copy the assets you selected to all the selected Takes in the Data pane.

Copying Assets from a Recorded _Take_** to the Live Capture**

If you have a list of assets in a Take that you wish to import into the live capture, you can simply do this by right-clicking on the desired assets on the Assets pane, and selecting Copy Assets to Live.

Exporting Assets

Assets can be exported into Motive user profile (.MOTIVE) file if it needs to be re-imported. The user profile is a text-readable file that can contain various configuration settings in Motive; including the asset definitions.

When the asset definition(s) is exported to a MOTIVE user profile, it stores marker arrangements calibrated in each asset, and they can be imported into different takes without creating a new one in Motive. Note that these files specifically store the spatial relationship of each marker, and therefore, only the identical marker arrangements will be recognized and defined with the imported asset.

To export the assets, go to Files tab → Export Assets to export all of the assets in the Live-mode or in the current TAK file. You can also use Files tab → Export Profile to export other software settings including the assets.

C3D Export

Tracking data can be exported into the C3D file format. C3D (Coordinate 3D) is a binary file format that is widely used especially in biomechanics and motion study applications. Recorded data from external devices, such as force plates and NI-DAQ devices, will be recorded within exported C3D files. Note that common biomechanics applications use a Z-up right-hand coordinate system, whereas Motive uses a Y-up right-hand coordinate system. More details on coordinate systems are described in the later section. Find more about C3D files from .

General Export Options

C3D Specific Export Options

C3D Axes

Common Conventions

Since Motive uses a different coordinate system than the system used in common biomechanics applications, it is necessary to modify the coordinate axis to a compatible convention in the C3D exporter settings. For biomechanics applications using z-up right-handed convention (e.g. Visual3D), the following changes must be made under the custom axis.

• X axis in Motive should be configured to positive X

• Y axis in Motive should be configured to negative Z

• Z axis in Motive should be configured to positive Y.

This will convert the coordinate axis of the exported data so that the x-axis represents the anteroposterior axis (left/right), the y-axis represents the mediolateral axis (front/back), and the z-axis represents the longitudinal axis (up/down).

MotionBuilder Compatible Axis Convention

This is a preset convention for exporting C3D files for use in Autodesk MotionBuilder. Even though Motive and MotionBuilder both use the same coordinate system, MotionBuilder assumes biomechanics standards when importing C3D files (negative X axis to positive X axis; positive Z to positive Y; positive Z to positive Y). Accordingly, when exporting C3D files for MotionBuilder use, set the Axis setting to MotionBuilder Compatible, and the axes will be exported using the following convention:

• Motive: X axis → Set to negative X → Mobu: X axis

• Motive: Y axis → Set to positive Z → Mobu: Y axis

• Motive: Z axis → Set to positive Y → Mobu: Z axis

Notes on Timecode Export

There is an known behavior where importing C3D data with timecode doesn't accurately show up in MotionBuilder. This happens because MotionBuilder sets the subframe counts in the timecode using the playback rate inside MotionBuilder instead of using the rate of the timecode. When this happens you can set the playback rate in MotionBuilder to be the same as the rate of the timecode generator (e.g. 30 Hz) to get correct timecode. This happens only with C3D import in MotionBuilder, FBX import will work fine without the change to the playback rate.

In Motive, Skeleton assets are used for tracking human motions. These assets auto-label specific sets of markers attached to human subjects, or actors, and create skeletal models. Unlike Rigid Body assets, Skeleton assets require additional calculations to correctly identify and label 3D reconstructed markers on multiple semi-Rigid Body segments. In order to accomplish this, Motive uses pre-defined Skeleton Marker Set templates, which is a collection of marker labels and their specific positions on a subject. According to the selected Marker Set, retroreflective markers must be placed on pre-designated locations of the body. This page details instructions on how to create and use Skeleton assets in Motive.

Skeleton Marker Placement

When it comes to tracking human movements, a proper marker placement becomes especially important. Motive utilizes pre-programmed Skeleton Marker Sets, and each marker is used to indicate anatomical landmarks when modeling the Skeleton. Thus, all of the markers must be placed at their appropriate locations. If any of markers are misplaced, the Skeleton asset may not be created, and even if it is created, bad marker placements may lead to problems. Thus, taking extra care in placing the markers on intended locations is very important and can save time in post-processing of the data.

Attaching markers directly onto a person’s skin can be difficult because of hairs, oils, and moistures from sweat. Plus, dynamic human motions tend to move the markers during capture, so use appropriate skin adhesives for securing marker bases onto the skin. Alternatively, mocap suits allow velcro marker bases to be used.

Select a Marker Set

Open and go to the Skeleton creation feature. Select the Marker Set you desire to use from the drop-down menu. A total number of required markers for each Skeleton is indicated in the parenthesis after each Marker Set name, and corresponding marker locations are displayed over an avatar that shows up in the . Instruct the subject to strike a calibration pose (T-pose or A-pose) and carefully follow the figure and place retroreflective markers at corresponding locations of the actor or the subject.

Placing the Markers

Joint Markers

Joint markers need to be placed carefully along corresponding joint axes. Proper placements will minimize marker movements during a range of motions and will give better tracking results. To accomplish this, ask the subject to flex and extend the joint (e.g. knee) a few times and palpate the joint to locate the corresponding axis. Once the axis is located, attach the markers along the axis where skin movement is minimal during a range of motion.

Segment Markers

Additional Placement Tips

• Wipe out any moisture or oil on the skin before attaching the marker.

• Avoid wearing clothing or shoes with reflective materials since they can introduce extraneous reflections.

• Tie up hair which can occlude the markers around the neck.

• Remove reflective jewelry.

• Place markers in an asymmetrical arrangement by offsetting the related segment markers (markers that are not on joints) in slightly different height.

Biomechanics Marker Sets

Creating Skeletons

Skeleton Creation Steps

Step 1.

Step 2.

Step 3.

Step 4.

Step 5.

Step 6.

Next step is to select the Skeleton creation pose settings. Under the Pose section drop-down menu, select the desired calibration post you want to use for defining the Skeleton. This is set to the T-pose by default.

Step 7.

Step 8.

Click Create to create the Skeleton. Once the Skeleton model has been defined, confirm all Skeleton segments and assigned markers are located at expected locations. If any of the Skeleton segment seems to be misaligned, delete and create the Skeleton again after adjusting the marker placements and the calibration pose.

Skeleton Properties

Calibration Pose

A proper calibration posture is necessary because the pose of the created Skeleton will be calibrated from it. Read through the following explanations on proper T-poses and A-poses.

T pose

The T-pose is commonly used as the reference pose in 3D animation to bind two characters or assets together. Motive uses this pose when creating Skeletons. A proper T-pose requires straight posture with back straight and head looking directly forward. Both arms are stretched to each side, forming a “T” shape. Both arms and legs must be straight, and both feet need to be aligned parallel to each other.

A pose

• Palms Down: Arms straight. Abducted, sideways, arms approximately 40 degrees, palms facing downwards.

• Palms forward: Arms straight. Abducted, sideways, arms approximately 40 degrees, palms facing forward. Be careful not to over rotate the arm.

• Elbows Bent: Similar to all other A-poses. arms approximately 40 degrees, bend elbows so that forearms point towards the front. Palms facing downwards, both forearms aligned.

Calibration Markers

Many Skeleton Marker Sets do not have medial markers because they can easily collide with other body parts or interfere with the range of motion, all of which increase the chance of marker occlusions.

However, medial markers are beneficial for precisely locating joint axes by associating two markers on the medial and lateral side of a joint. For this reason, some biomechanics Marker Sets use medial markers as calibration markers. Calibration markers are used only when creating Skeletons but removed afterward for the actual capture. These calibration markers are highlighted in red from the 3D view when a Skeleton is first created.

Recalibrating Skeleton

Existing Skeleton assets can be recalibrated using the existing Skeleton information. Basically, the recalibration recreates the selected Skeleton using the same Skeleton Marker Set. This feature recalibrates the Skeleton asset and refreshes expected marker locations on the assets.

Marker Colors and Marker Sticks

Adding/Removing Skeleton Markers

Skeleton Marker Sets can be modified slightly by adding or removing markers to or from the template. Follow the below steps for adding/removing markers. Note that modifying, especially removing, Skeleton markers is not recommended since changes to default templates may negatively affect the Skeleton tracking when done incorrectly. Removing too many markers may result in poor Skeleton reconstructions while adding too many markers may lead to labeling swaps. If any modification is necessary, try to keep the changes minimal.

Steps

To Add

2. Select a Skeleton segment that you wish to add extra markers onto.

3. Then, CTRL + left-click on an the marker that we wish to add to the template

4. On the Asset Model Markers tool in the Builder pane, click + to add and associate the selected marker to the selected segment

5. Reconstruct and Auto-label the Take.

To Remove

2. [Optional] Under the advanced properties of the target Skeleton, enable Marker Lines property to view which markers are associated with different Skeleton bones.

5. Delete the association by clicking on the "-" next to the Asset Model Markers tool in the Builder pane while both the target marker and the target segment is selected.

6. Reconstruct and Auto-label the Take.

Export Assets Definition

When the asset definition(s) is exported to a MOTIVE user profile, it stores marker arrangements calibrated in each asset, and they can be imported into different takes without creating a new one in Motive. Note that these files specifically store the spatial relationship of each marker, and therefore, only the identical marker arrangements will be recognized and defined with the imported asset.

To export the assets, go to Files tab → Export Assets to export all of the assets in the Live-mode or in the current TAK file. You can also use Files tab → Export Profile to export other software settings including the assets.

Relative Skeleton Joint Angles

For biomechanics applications, joint angles must be computed accurately using respective Skeleton model solve, which can be accomplished by using biomechanical analysis software. Export C3D files or stream tracking data from Motive and import them into an analysis software for further calculation. From the analysis, various biomechanics metrics, including the joint angles can be obtained.

Constraints XML: Customize Marker Labels, Colors, and Sticks

To export Skeleton constraints XML file

To import Skeleton constraints XML file

Once the capture volume is calibrated and all markers are placed, you are now ready to capture Takes. In this page, we will cover key concepts and tips that are important for the recording pipeline. For real-time tracking applications, you can skip this page and read through the page.

Live Mode and Edit Mode

There are two different modes in Motive: Live mode and Edit mode. You can toggle between two modes from the or by using the (Shift + ~) hotkey.

Live Mode

The Live mode is mainly used when recording new Takes or when streaming a live capture. In this mode, all of the cameras are continuously capturing 2D images and reconstructing the detected reflections into 3D data in real-time.

Edit Mode

The Edit Mode is used for playback of captured Take files. In this mode, you can playback, or stream, recorded data. Also, captured Takes can be post-processed by fixing mislabeling errors or interpolating the occluded trajectories if needed.

Recording

Control Deck

Recorded Data Management

Recorded Data Types

• 2D data: The recorded Take file includes just the 2D object images from each camera.

• 3D data: The recorded Take file also includes reconstructed 3D marker data in addition to 2D data.

Marker Types in Motive

Unlabeled and Labeled

Marker data, labeled or unlabeled, represent the 3D positions of markers. These markers do not present Rigid Body or Skeleton solver calculations but locate the actual marker position calculated from the camera data. These markers are represented as a solid sphere in the viewport. By default, unlabeled markers are colored in white, and labeled markers will have colors that reflect the color setting in the Rigid Body or the corresponding bone.

Expected Marker Positions: Rigid Body Markers and Bone Markers

Rigid body markers or bone markers are expected marker positions. They appear as transparent spheres within a rigid body, or a skeleton, and they reflect the position that the rigid body or skeleton solver expects to find a corresponding reconstructed marker. Calculating these positions assumes that the marker is fixed on a rigid segment that doesn’t deform over the course of capture. When the rigid body solver or skeleton solver are correctly tracking reconstructed markers, both marker reconstructions, and expected marker positions will have similar position values and will closely align in the viewport.

When creating rigid bodies, their associated markers will appear as a network of lines between markers. Skeleton marker expected positions would be located next to body segments, or bones. Please see Figure 2. If the marker placement is distorted during capture, the actual marker position will deviate from the expected position. Eventually, the marker may become unlabeled. Figure 1. shows how actual and expected marker positions could align or deviate from each other. Due to the nature of marker-based mocap systems, labeling errors may occur during capture. Thus, understanding each marker type in Motive is very important for correct interpretation of the data.

This page provides some information on aligning a Rigid Body pivot point with a real object replicated 3D model.

Overview

When using streamed Rigid Body data to animate a real-life replicate 3D model, the alignment of the pivot point is necessary. In other words, the location of the Rigid Body pivot coincides with the location of the pivot point in the corresponding 3D model. If they are not aligned accurately, the animated motion will not be in a 1:1 ratio compared to the actual motion. This alignment is commonly needed for real-time VR applications where real-life objects are 3D modeled and animated in the scene. The suggested approaches for aligning these pivot points will be discussed on this page.

Aligning Rigid Body Pivot Point

There are two methods for doing this. Using a measurement probe to sample 3D points to reference from, or simply using a reference grayscale view to align. The first method of creating and using a measurement probe is most accurate and recommended.

Method 1: Using Measurement Probe Feature

Step 1. Create a Rigid Body of the target object

First of all, create a Rigid Body from the markers on the target object. By default, the pivot point of the Rigid Body will be positioned at the geometrical center of the marker placement. Then place the object onto somewhere stable where it will stay stationary.

Step 2. Create a measurement probe.

Step 3. Collect data points to outline the silhouette

Step 4. Attach 3D model

Step 5. Translate the pivot point

Step 6. Copy transformation values

Step 7. Zero all transformation values in the Attached Geometry section

Once the Rigid Body pivot point has been moved using the Builder pane, zero all of the transformation configurations under the Attached Geometry property for the Rigid Body.

Method 2: Using Reference Grayscale View

This page provides instructions on how to utilize the Gizmo tool for modifying asset definitions (Rigid Bodies and Skeletons) on the of Motive

Overview

The gizmo tools allow users to make modifications on reconstructed 3D markers, Rigid Bodies, or Skeletons for both real-time and post-processing of tracking data. This page provides instructions on how to utilize the gizmo tools.

Rigid Body Assets

Using the gizmo tools from the perspective view options to easily modify the position and orientation of Rigid Body pivot points. You can translate and rotate Rigid Body pivot, assign pivot to a specific marker, and/or assign pivot to a mid-point among selected markers.

• Select Tool (Hotkey: Q): Select tool for normal operations.

• Translate Tool (Hotkey: W): Translate tool for moving the Rigid Body pivot point.

• Rotate Tool (Hotkey: E): Rotate tool for reorienting the Rigid Body coordinate axis.

• Scale Tool (Hotkey: R): Scale tool for resizing the Rigid Body pivot point.

Translation

Rotation

Rescale

Skeleton Assets

You can utilize the gizmo tools to modify skeleton bone lengths, joint orientations, or scale the spacing of the markers. Translating and rotating the skeleton assets will change how skeleton bone is positioned and oriented with respect to the tracked markers, and thus, any changes in the skeleton definition will affect the realistic representation of the human movement.

Translation

Rotation

Scale

The scale tool modifies the size of selected skeleton segments.

Reconstructed 3D Markers

The gizmo tools can also be used to edit positions of reconstructed markers.In order to do this, you must be working reconstructed 3D data in post-processing. In live-tracking or 2D mode doing live-reconstruction, marker positions are reconstructed frame-by-frame and it cannot be modified. The Edit Assets must be disabled to do this (Hotkey: T).

Translate

Using the translate tool, 3D positions of reconstructed markers can be modified. Simply click on the markers, turn on the translate tool (Hotkey: W), and move the markers.

Rotate

Using the rotate tool, 3D positions of a group of markers can be rotated at its center. Simply select a group of markers, turn on the rotate tool (Hotkey: E), and rotate them.\

Scale

Using the scale tool, 3D spacing of a group of makers can be scaled. Simply select a group of markers, turn on the scale tool (Hotkey: R) and scale their spacing.

Cameras

Cameras can be modified using the gizmo tool if the Settings Window > General > Calibration > "Editable in 3D View" property is enabled. Without this property turned on the gizmo tool will not activate when a camera is selected to avoid accidentally changing a calibration. The process for using the gizmo tool to fix a misaligned camera is as follows:

1. Select the camera you wish to fix, then view from that camera (Hotkey: 3).

2. Select either the Translate or Rotate gizmo tool (Hotkey: W or E).

3. Use the red diamond visual to align the unlabeled rays roughly onto their associated markers.

4. Right lock then choose "Correct Camera Position/Orientation". This will perform a calculation to place the camera more accurately.

5. Turn on Continuous Calibration if not already done. Continuous calibration should finish aligning the camera into the correct location.

This page explains different types of captured data in Motive. Understanding these types is essential in order to fully utilize the data-processing pipelines in Motive.

Overview

There are three different types of data: 2D data, 3D data, and Solved data. Each type of data will be covered in detail throughout this page, but basically, 2D Data is the captured camera frame data, 3D Data is the reconstructed 3-dimensional marker data, and Solved data is the calculated positions and orientations of and segments.

Motive saves tracking data into a Take file (TAK extension), and when a capture is initially recorded, all of the 2D data, real-time reconstructed 3D data, and solved data are saved onto a Take file. Recorded 3D data can be post-processed further in , and when needed, a new set of 3D data can be re-obtained from saved 2D data by performing the reconstruction pipelines. From the 3D data, Solved data can be derived.

Available data types are listed on the . When you open up a Take in , the loaded data type will be highlighted at the top-left corner of the 3D viewport. If available, 3D Data will be loaded first by default, and the 2D data can be accessed by entering the from the Data pane.

Data Types

2D data

2D data is the foundation of motion capture data. It mainly includes the 2D frames captured by each camera in a system.

• Recorded 2D data can be reconstructed and auto-labeled to derive the 3D data.

• 3D tracking data is not computed yet. The tracking data can be exported only after reconstructing the 3D data.

• In playback of recorded 2D data, 3D data will be Live-reconstructed into 3D data and reported in the 3D viewport.

3D data

• Reconstructed 3D marker positions.

• Marker labels can be assigned.

• Assets are modeled and the tracking information is available.

Solved Data

Record Solved Data

Deleting Data

Deleting 2D/Video/Audio data

Deleting 3D Data

Deleting 3D data for a single _Take_

When frame range is not selected, it will delete 3D data from the entire frame. When a frame range is selected from the Timeline Editor, this will delete 3D data in the selected ranges only.

Deleting 3D data for multiple _Takes_

Deleting Solved Data

When a Rigid Body or Skeleton exists in a Take, Solved data can be recorded. From the Assets pane, right-click one or more asset and select Solve from the context menu to calculate the solved data. To delete, simply click Remove Solve.

Deleting Marker Labels

Deleting labels for a single _Take_

When no frame range is selected, it will unlabel all markers from all Takes. When a frame range is selected from the Timeline Editor, this will unlabel markers in the selected ranges only.

Deleting labels for multiple _Takes_

Even when a frame range is selected from the timeline, it will unlabel all markers from all frame ranges of the selected Takes.

During process, a calibration square is used to define global coordinate axes as well as the ground plane for the capture volume. Each calibration square has different vertical offset value. When defining the ground plane, Motive will recognize the square and ask user whether to change the value to the matching offset.

Custom Calibration Square

Coordinate System (Motive 1.7+)

For Motive 1.7 or higher, Right-Handed Coordinate System is used as the standard, across internal and exported formats and data streams. As a result, Motive 1.7 now interprets the L-Frame differently than previous releases:

The Edit Tools in Motive enables users to post-process tracking errors from recorded capture data. There are multiple editing methods available, and you need to clearly understand them in order to properly fix errors in captured trajectories. Tracking errors are sometimes inevitable due to the nature of marker-based motion capture systems. Thus, understanding the functionality of the editing tools is essential. Before getting into details, note that the post-editing of the motion capture data often takes a lot of time and effort. All captured frames must be examined precisely and corrections must be made for each error discovered. Furthermore, some of the editing tools implement mathematical modifications to marker trajectories, and these tools may introduce discrepancies if misused. For these reasons, we recommend optimizing the capture setup so that tracking errors are prevented in the first place.

Common tracking errors include marker occlusions and labeling errors. Labeling errors include unlabeled markers, mislabeled markers, and label swaps. Fortunately, label errors can be corrected simply by reassigning proper labels to markers. Markers may be hindered from camera views during capture. In this case, the markers will not be reconstructed into 3D space and introduce a gap in the trajectory, which are referred to as marker occlusions. Marker occlusions are critical because the trajectory data is not collected at all, and retaking the capture could be necessary if the missing marker is significant to the application. For these occluded markers, Edit Tools also provide interpolation pipelines to model the occluded trajectory using other captured data points. Read through this page to understand each of data editing methods in detail.

Steps in Editing

General Steps

1. Skim through the overall frames in a Take to get an idea of which frames and markers need to be cleaned up.

2. Refer to the Labels pane and inspect gap percentages in each marker.

3. Select a marker that is often occluded or misplaced.

4. Look through the frames in the Graph pane, and inspect the gaps in the trajectory.

5. For each gap in frames, look for an unlabeled marker at the expected location near the solved marker position. Re-assign the proper marker label if the unlabeled marker exists.

6. Use Trim Tails feature to trim both ends of the trajectory in each gap. It trims off a few frames adjacent to the gap where tracking errors might exist. This prepares occluded trajectories for Gap Filling.

7. Find the gaps to be filled, and use the Fill Gaps feature to model the estimated trajectories for occluded markers.

Deleting Frames

In some cases, you may wish to delete 3D data for certain markers in a Take file. For example, you may wish to delete corrupt 3D reconstructions or trim out erroneous movements from the 3D data to improve the data quality. In the Edit mode, reconstructed 3D markers can be deleted for selected range of frames. To delete a 3D marker, first select 3D markers that you wish to delete, and press the Delete key, and they will be completely erased from the 3D data. If you wish to delete 3D markers for a specific frame range, open the Graph Pane and select the frame ranges that you wish to delete the markers from, and press the Delete key. The 3D trajectory for the selected markers will be erased for the highlighted frame range.

Note: Deleted 3D data can be recovered by reconstructing and auto-labeling new 3D data from recorded 2D data.

Trimming Captured Takes

The trimming feature can be used to crop a specific frame range from a Take. For each round of trim, a copied version of the Take will be automatically achieved and backed up into a separate session folder.

Steps for trimming a Take

1) Determine a frame range that you wish to extract.

2) Set the working range (also called as the view range) on the Graph View pane. All other frames outside of this range will be trimmed out. You can set the working range through the following approaches:

• Specify the starting frame and ending frame from the navigation bar on the Graph Pane.

3) After zooming into the desired frame range, click Edit > Trim Current Range to trim out the unnecessary frames.

4) A dialog box will pop up asking to confirm the data removal. If you wish to reset the frame numbers upon trimming the take, select the corresponding check box on the pop-up dialog.

Labeling Errors

The first step in the post-processing is to check for labeling errors. Labels can be lost or mislabeled to irrelevant markers either momentarily or entirely during capture. Especially when the marker placement is not optimized or when there are extraneous reflections, labeling errors may occur. As mentioned in other pages, marker labels are vital when tracking a set of markers, because each label affects how the overall set is represented. Examine through the recorded capture and spot the labeling errors from the perspective view, or by checking the trajectories on the Graph pane for suspicious markers. Use the Labels pane or the Tracks View mode from the Graph pane to monitor unlabeled markers in the Take.

When a marker is unlabeled momentarily, the color of tracked marker switches between white (labeled) and orange (unlabeled) by the default color setting. Mislabeled markers may have large gaps and result in a crooked model and trajectory spikes. First, explore captured frames and find where the label has been misplaced. As long as the target markers are visible, this error can easily be fixed by reassigning the correct labels. Note that this method is preferred over editing tools because it conserves the actual data and avoids approximation.

Read more about labeling markers from the Labeling page.

Edit Tools

The Edit Tools provide functionality to modify and clean-up 3D trajectory data after a capture has been taken. multiple post-processing methods are featured in the Edit Tools for different purposes: Trim Tails, Fill Gaps, Smooth, and Swap Fix. The Trim Tails method is used to remove data points in few frames before and after a gap. The Fill Gaps method calculates the missing marker trajectory using interpolation methods. The Smoothing method filters out unwanted noise in the trajectory signal. Finally, the Swapping method switches marker labels for two selected markers. Remember that modifying data using Edit Tools changes the raw trajectories, and an overuse of Edit Tools is not recommended. Read through each method and familiarize yourself with the Editing Tools. Note that you can undo and redo all changes made using Edit Tools.

Tails

The Tails method trims, or removes, a few data points before and after a gap. Whenever there is a gap in a marker trajectory, slight tracking distortions may be present on each end. For this reason, it is usually beneficial to trim off a small segment (~3 frames) of data. Also, if these distortions are ignored, they may interfere with other editing tools which rely on existing data points. Before trimming trajectory tails, check all gaps to see if the tracking data is distorted. After all, it is better to preserve the raw tracking data as long as they are relevant. Set the appropriate trim settings, and trim out the trajectory on selected or all frame. Each gap must satisfy the gap size threshold value for it to be considered for trimming. Each trajectory segment also needs to satisfy the minimum segment size, otherwise, it will be considered as a gap. Finally, the Trim Size value will determine how many leading and trailing trajectory frames are removed from a gap.

Smart Trim

The Smart Trim feature automatically sets the trimming size based on trajectory spikes near the existing gap. It is often not needed to delete numerous data points before or after a gap, but there are some cases where it's useful to delete more data points than others. This feature determines whether each end of the gap is suspicious with errors, and deletes an appropriate number of frames accordingly. Smart Trim feature will not trim more frames than the defined Leading and Trailing value.

Gaps

Gap filling is the primary method in the data editing pipeline, and this feature is used to remodel the trajectory gaps with interpolated marker positions. This is used to accommodate the occluded markers in the capture. This function runs mathematical modeling to interpolate the occluded marker positions from either the existing trajectories or other markers in the asset. Note that interpolating a large gap is not recommended because approximating too many data points may lead to data inaccuracy.

New to Motive 3.0; For Skeletons and Rigid Bodies only Model Asset Markers can be used to fill individual frames where the marker has been occluded. Model Asset markers must be first enabled on the Properties Pane when the desired asset is selected and then they must be enabled for selection in the Viewport. Now when frames are encountered where the marker is lost from camera view, select the associated Model Asset Marker in the 3D view; right click for the context menu and select 'Set Key'.

First of all, set the Max. Gap Size value and define the maximum frame length for an occlusion to be considered as a gap. If a gap size has a longer frame length, it will not be affected by the filling mechanism. Set a reasonable maximum gap size for the capture after looking through the occluded trajectories. In order to quickly navigate through the trajectory graphs on the Graph Pane for missing data, use the Find Gap features (Find Previous and Find Next) and automatically select a gap frame region so the data could be interpolated. Then, apply the Fill Gaps feature while the gap region is selected. Various interpolation options are available in the setting including Constant, Linear, Cubic, Pattern-based, and Model-based.

Interpolation options

There are four different interpolation options offered in Edit Tools: constant, linear, cubic and pattern-based. First three interpolation methods (constant, linear, and cubic) look at the single marker trajectory and attempt to estimate the marker position using the data points before and after the gap. In other words, they attempt to model the gap via applying different degrees of polynomial interpolations. The other two interpolation options (pattern-based and model-based) reference visible markers and models to the estimate occluded marker position.

Constant

Applies zero-degree approximation, assumes that the marker position is stationary and remains the same until the next corresponding label is found.

Linear

Applies first-degree approximation, assuming that the motion is linear, to fill the missing data. Only use this when you are sure that the marker is moving at linear motion.

Cubic

Applies third-degree polynomial interpolation, cubic spline, to fill the missing data in the trajectory.

Pattern based

This refers to trajectories of selected reference markers and assumes the target marker moves along in a similar pattern. The Fill Target marker is specified from the drop-down menu under the Fill Gaps tool. When multiple markers are selected, a Rigid Body relationship is established among them, and the relationship is used to fill the trajectory gaps of the selected Fill Target marker as if they were all attached to a same Rigid Body. The following list is the general workflow for using the Pattern Based interpolation:

1. Select both reference markers and the target marker to fill.

2. Examine the trajectory of the target marker from the Graph Pane: Size, range, and a number of gaps.

3. Set an appropriate Max. Gap Size limit.

4. Select the Pattern Based interpolation option.

5. Specify the Fill Target marker in the drop-down menu.

6. When interpolating for only a specific section of the capture, select the range of frames from Graph pane.

7. Click the Fill Selected/Fill All/Fill Everything.

Model based

This interpolation is used for filling markers gaps of an asset (skeleton segments or rigid bodies). Model based interpolation refers to the model and corresponding expected marker positions for estimating the trajectory. When using this option on a skeleton asset, the other skeleton markers and related segments determine a reliable location of the marker during the occluded gap. When using this option, simply select a gapped marker within a model, configure the Max. Gap Size value, and apply the interpolation in the desired frame range.

Smooth

The smoothing feature applies a noise filter (low-pass Butterworth, 4th degree) to trajectory data, and this modifies the marker trajectory smoother. This is a bi-directional filter that does not introduce phase shifts. Using this tool, any vibrating or fluttering movements can be filtered out. First of all, set the cutoff frequency for the filter and define how strongly your data will be smoothed.

When the cutoff frequency is set high, only high-frequency signals are filtered. When the cutoff frequency is low, trajectory signals at a lower frequency range will also be filtered. In other words, a low cutoff frequency setting will smooth most of the transitioning trajectories, whereas high cutoff frequency setting will smooth only the fluttering trajectories.

High-frequency data are present during sharp transitions, and this can also be introduced by signal noise. Commonly used ranges for Filter Cutoff Frequency are between 7 Hz to 12 Hz, but you may want to adjust the value higher for fast and sharp motions to avoid softening motion transitions need to stay sharp.

Swap Fix

In some cases, marker labels may be swapped during capture. Swapped labels can result in erratic orientation changes, or crooked skeletons, but they can be corrected by re-labeling the markers. The Swap Fix feature in the Edit Tools can be used to correct obvious swaps that persist through the capture. Select two markers that have their labels swapped, and select the frame range that you wish to edit.

Find Previous and Find Next buttons allow you to navigate to the frame where their position have been changed. If a frame range is not specified, the change will be applied from current frame forward. Finally, switch the marker labels by clicking on the Apply Swap button. As long as both labels are present in the frame and only correction needed is to change the labels, the Swap Fix tool could be utilized to make corrections.

Various types of files, including the tracking data, can be exported out from Motive. This page provides information on what file formats can be exported from Motive and instructions on how to export them.

Tracking Data Export

Once captures have been recorded into Take files and the corresponding 3D data have been reconstructed, tracking data can be exported from Motive in various file formats.

Exporting Rigidbody Tracking Data

If the recorded Take includes Rigid Body trackable assets, make sure all of the Rigid Bodies are Solved prior to exporting. The solved data will contain positions and orientations of each Rigid Body.

Export Settings

In the export dialog window, the frame rate, the measurement scale, and the frame range of exported data can be configured. Additional export settings are available for each export file formats. Read through below pages for details on export options for each file format:

• Data Export: CSV

• Data Export: C3D

• Data Export: FBX

• Data Export: BVH

• Data Export: TRC

Tracking Data Export Steps

Exporting a Single Take

Step 1. Open and select a Take to export from the Data pane. The selected Take must contain reconstructed 3D data.

Step 2. Under the File tab on the command bar, click File → Export Tracking Data. This can also be done by right-clicking on a selected Take from the Data pane and clicking Export Tracking Data from the context menu.

Step 3. On the export dialogue window, select a file format and configure the corresponding export settings.

• To export the entire frame range, set Start Frame and End Frame to Take First Frame and Take Last Frame.

• To export a specific frame range, set Start Frame and End Frame to Start of Working Range and End of Working Range.

Step 4. Click Save.

Exporting Multiple Takes

Step 1. Under the Data pane, shift + select all the Takes that you wish to export.

Step 2. Right-click on the selected Takes and click Export Tracking Data from the context menu.

Step 3. An export dialogue window will show up for batch exporting tracking data.

Step 4. Select the desired output format and configure the corresponding export settings.

Step 5. Select frame ranges to export under the Start Frame and the End Frame settings. You can either export entire frame ranges or specified frame ranges on all of the Takes. When exporting specific ranges, desired working ranges must be set for each respective Takes.

• To export entire frame ranges, set Start Frame and End Frame to Take First Frame and Take Last Frame.

• To export specific frame ranges, set Start Frame and End Frame to Start of Working Range and End of Working Range.

Step 6. Click Save.

File Formats

Motive exports reconstructed 3D tracking data in various file formats and exported files can be imported into other pipelines to further utilize capture data. Available export formats include CSV, C3D, FBX, BVH, and TRC. Depending on which options are enabled, exported data may include reconstructed marker data, 6 Degrees of Freedom (6 DoF) Rigid Body data, or Skeleton data. The following chart shows what data types are available in different export formats:

Camera Calibration Export

A calibration definition of a selected take can be exported from the Export Camera Calibration under the File tab. Exported calibration (CAL) files contain camera positions and orientations in 3D space, and they can be imported in different sessions to quickly load the calibration as long as the camera setup is maintained.

Read more about calibration files under the Calibration page.

Export Assets Definition

Recorded NI-DAQ analog channel data can be exported into C3D and CSV files along with the mocap tracking data. Follow the tracking data export steps outlined above and any analog data that exists in the TAK will also be exported.

When an asset definition is exported to a MOTIVE user profile, it stores marker arrangements calibrated in each asset, and they can be imported into different takes without creating a new asset in Motive. Note that these files specifically store the spatial relationship of each marker, and therefore, only the identical marker arrangements will be recognized and defined with the imported asset.

To export the assets, go to the File menu and select Export Assets to export all of the assets in the Live-mode or in the current TAK file(s). You can also use File → Export Profile to export other software settings including the assets.

Analog Data Export

Recorded NI-DAQ analog channel data can be exported into C3D and CSV files along with the mocap tracking data. Follow the tracking data export steps outlined above and any analog data that exists in the TAK will also be exported.

C3D Export: Both mocap data and the analog data will be exported onto a same C3D file. Please note that all of the analog data within the exported C3D files will be logged at the same sampling frequency. If any of the devices are captured at different rates, Motive will automatically resample all of the analog devices to match the sampling rate of the fastest device. More on C3D files: https://www.c3d.org/

CSV Export: When exporting tracking data into CSV, additional CSV files will be exported for each of the NI-DAQ devices in a Take. Each of the exported CSV files will contain basic properties and settings at its header, including device information and sample counts. The voltage amplitude of each analog channel will be listed. Also, mocap frame rate to device sampling ratio is included since analog data is usually sampled at higher sampling rates.

Common Conventions

Since Motive uses a different coordinate system than the system used in common biomechanics applications, it is necessary to modify the coordinate axis to a compatible convention in the C3D exporter settings. For biomechanics applications using z-up right-handed convention (e.g. Visual3D), the following changes must be made under the custom axis.

• X axis in Motive should be configured to positive X

• Y axis in Motive should be configured to negative Z

• Z axis in Motive should be configured to positive Y.

This will convert the coordinate axis of the exported data so that the x-axis represents the anteroposterior axis (left/right), the y-axis represents the mediolateral axis (front/back), and the z-axis represents the longitudinal axis (up/down).

Reference Video Export

When there is an MJPEG reference camera in a Take, its recorded video can be exported into an AVI file or into a sequence of JPEG files. The Export Video option is located under the File tab or you can also right-click on a TAK file from the Data pane and export from there. At the bottom of the export dialog, the frame rate of the exported AVI file can be set to a full-frame rate or down-sampled to half, quarter, 1/8, or 1/16 ratio framerate. You can also adjust the playback speed to export a video with a slower or faster playback speed. The captured reference videos can be exported into AVI files using either H.264 or MJPEG compression format. The H.264 format will allow faster export of the recorded videos and is recommended. Read more about recording reference videos on Data Recording page.

Audio Export

When a recorded capture contains audio data, an audio file can be exported through the Export Audio option that appears when right-clicking on a Take from the Data pane.

Export Skeleton Marker Labels

Skeletal marker labels for Skeleton assets can be exported as XML files (example shown below) from the Data pane. The XML files can be imported again to use the stored marker labels when creating new Skeletons.

For more information on Skeleton XML files, read through the Skeleton Tracking page.

Sample Skeleton Label XML File

 <Asset version="1.0">
    <MarkerNames ReorderMarkers="true">
        <Marker name="NewHeadTop" oldName="HeadTop" />
        <Marker name="NewHeadFront" oldName="HeadFront" />
        <Marker name="NewHeadSide" oldName="HeadSide" />
        ...
        <Marker name="RToeIn" oldName="RToeIn" />
        <Marker name="RToeTip" oldName="RToeTip" />
        <Marker name="RToeOut" oldName="RToeOut" />
    </MarkerNames>
    <MarkerColors>
        <Marker name="WaistLFront" color="75 225 255" movable="false" />
        <Marker name="WaistRFront" color="225 75 255" movable="false" />
        <Marker name="WaistLBack" color="75 225 255" movable="false" />
        ...
        <Marker name="RToeIn" color="225 75 255" movable="false" />
        <Marker name="RToeOut" color="75 75 255" movable="false" />
        <Marker name="RHeel" color="225 75 255" movable="false" />
        <Marker name="RToeTip" color="0 150 0" movable="false" />
    </MarkerColors>
    <MarkerSticks>
        <MarkerStick origin="WaistLFront" end="WaistLBack" color="140 45 225" />
        <MarkerStick origin="WaistLFront" end="LThigh" color="110 210 240" />
        <MarkerStick origin="WaistRFront" end="WaistRBack" color="140 45 225" />
        ...
        <MarkerStick origin="RToeTip" end="RToeIn" color="60 210 60" />
        <MarkerStick origin="LToeTip" end="LToeOut" color="110 210 240" />
        <MarkerStick origin="RToeTip" end="RToeOut" color="60 210 60" />
    </MarkerSticks>
 </Asset>

In Motive, Rigid Body assets are used for tracking rigid, unmalleable, objects. A set of markers get securely attached to tracked objects, and respective placement information gets used to identify the object and report 6 Degree of Freedom (6DoF) data. Thus, it's important that the distances between placed markers stay the same throughout the range of motion. Either passive retro-reflective markers or active LED markers can be used to define and track a Rigid Body. This page details instructions on how to create rigid bodies in Motive and other useful features associated with the assets.

Rigid Body Marker Placement

A Rigid Body in Motive is a collection of three or more markers on an object that are interconnected to each other with an assumption that the tracked object is unmalleable. More specifically, it assumes that the spatial relationship among the attached markers remains unchanged and the marker-to-marker distance does not deviate beyond the allowable deflection tolerance defined under the corresponding Rigid Body properties. Otherwise, involved markers may become unlabeled. Cover any reflective surfaces on the Rigid Body with non-reflective materials, and attach the markers on the exterior of the Rigid Body where cameras can easily capture them.

Number of Markers

In a 3D space, a minimum of three coordinates is required for defining a plane using vector relationships; likewise, at least three markers are required to define a Rigid Body in Motive. Whenever possible, it is best to use 4+ markers to create a Rigid Body. Additional markers provide more 3D coordinates for computing positions and orientations of a rigid body, making overall tracking more stable and less vulnerable to marker occlusions. When any of markers are occluded, Motive can reference to other visible markers to solve for the missing data and compute position and orientation of the rigid body.

However, placing too many markers on one Rigid Body is not recommended. When too many markers are placed in close vicinity, markers may overlap on the camera view, and Motive may not resolve individual reflections. This may increase the likelihood of label-swaps during capture. Securely place a sufficient number of markers (usually less than 10) just enough to cover the main frame of the Rigid Body.

Asymmetrical Marker Placements

Within a Rigid Body asset, its markers should be placed asymmetrically because this provides a clear distinction of orientations. Avoid placing the markers in symmetrical shapes such as squares, isosceles, or equilateral triangles. Symmetrical arrangements make asset identification difficult, and they may cause the Rigid Body assets to flip during capture.

Unique Marker Placements

When tracking multiple objects using passive markers, it is beneficial to create unique Rigid Body assets in Motive. Specifically, you need to place retroreflective markers in a distinctive arrangement between each object, and it will allow Motive to more clearly identify the markers on each Rigid Body throughout capture. In other words, their unique, non-congruent, arrangements work as distinctive identification flags among multiple assets in Motive. This not only reduces processing loads for the Rigid Body solver, but it also improves the tracking stability. Not having unique Rigid Bodies could lead to labeling errors especially when tracking several assets with similar size and shape.

What Makes Rigid Bodies Unique?

The key idea of creating unique Rigid Body is to avoid geometrical congruency within multiple Rigid Bodies in Motive.

• Unique Marker Arrangement. Each Rigid Body must have a unique, non-congruent, marker placement creating a unique shape when the markers are interconnected.

• Unique Marker-to-Marker Distances. When tracking several objects, introducing unique shapes could be difficult. Another solution is to vary Marker-to-marker distances. This will create similar shapes with varying sizes, and make them distinctive from the others.

• Unique Marker Counts Adding extra markers is another method of introducing the uniqueness. Extra markers will not only make the Rigid Bodies more distinctive, but they will also provide more options for varying the arrangements to avoid the congruency.

What Happens When Rigid Bodies Are Not Unique?

Having multiple non-unique Rigid Bodies may lead to mislabeling errors. However, in Motive, non-unique Rigid Bodies can also be tracked fairly well as long as the non-unique Rigid Bodies are continuously tracked throughout capture. Motive can refer to the trajectory history to identify and associate corresponding Rigid Bodies within different frames. In order to track non-unique Rigid Bodies, you must make sure the Properties → General Settings → Unique setting in Rigid Body Properties of the assets are set to False.

Even though it is possible to track non-unique Rigid Bodies, it is strongly recommended to make each asset unique. Tracking of multiple congruent Rigid Bodies could be lost during capture either by occlusion or by stepping outside of the capture volume. Also, when two non-unique Rigid Bodies are positioned in vicinity and overlap in the scene, their marker labels may get swapped. If this happens, additional efforts will be required for correcting the labels in post-processing of the data.

Multiple Rigid Bodies Tracking

Depending on the object, there could be limitations on marker placements and number of variations of unique placements that could be achieved. The following list provides sample methods for varying unique arrangements when tracking multiple Rigid Bodies.

1. Create Distinctive 2D Arrangements. Create distinctive, non-congruent, marker arrangements as the starting point for producing multiple variations, as shown in the examples above.

2. Vary heights. Use marker bases or posts, with different heights to introduce variations in elevation to create additional unique arrangements.

3. Vary Maximum Marker to Marker Distance. Increase or decrease the overall size of the marker arrangements.

4. Add Two (or more) Markers Lastly, if an additional variation is needed, add extra markers to introduce the uniqueness. We recommended adding at least two extra markers in case any of them is occluded.

Creating Rigid Body

A set of markers attached to a rigid object can be grouped and auto-labeled as a Rigid Body. This Rigid Body definition can be utilized in multiple takes to continuously auto-label the same Rigid Body markers. Motive recognizes the unique spatial relationship in the marker arrangement and automatically labels each marker to track the Rigid Body. At least three coordinates are required to define a plane in 3D space, and therefore, a minimum of three markers are essential for creating a Rigid Body.

Steps to Create Rigid Bodies

Step 1.

Select all associated Rigid Body markers in the 3D viewport.

Step 2.

On the Builder pane, confirm that the selected markers match the markers that you wish to define the Rigid Body from.

Step 3.

Click Create to define a Rigid Body asset from the selected markers.

You can also create a Rigid Body by doing the following actions while the markers are selected:

• Perspective View (3D viewport): While the markers are selected, right-click on the perspective view to access the context menu. Under the Rigid Body section, click Create From Selected Markers.

• Hotkey: While the markers are selected, use the create Rigid Body hotkey (Default: Ctrl +T).

Step 4.

Once the Rigid Body asset is created, the markers will be colored (labeled) and interconnected to each other. The newly created Rigid Body will be listed under the Assets pane.

Rigid Body Properties

Rigid Body properties consist of various configurations of Rigid Body assets in Motive, and they determine how Rigid Bodies are tracked and displayed in Motive. For more information on each property, read through the Properties: Rigid Body page.

Default Properties

When a Rigid Body is first created, default Rigid Body properties are applied to the newly created assets. The default creation properties are configured under the Assets section in the Application Settings panel.

Modifying Properties

Properties for existing Rigid Body assets can be changed from the Properties pane.

Adding or Removing Markers

An existing rigid body can be modified by adding or removing markers using the context menu.

1. First select a rigid body from the Assets pane or by selecting the pivot point in the Perspective View.

2. Ctrl + left-click the markers that you wish to add/remove.

3. Left-click on the Perspective View pane to open the rigid body context menu.

4. Under Rigid Body, choose Add/Remove selected markers to/from rigid body.

5. If needed, right-click on the rigid body and select Reset Pivot to relocate the pivot point to the new center.

Editing/Refining Rigid Body

Created rigid body definitions can be modified using the editing tools in the Builder pane or by using the steps covered in the following sections.

Tracking Rigid Body

The pivot point of a Rigid Body is used to define both position and orientation. When a rigid body is created, its pivot point is be placed at its geometric center by default, and its orientation axis will be aligned with the global coordinate axis. To view the pivot point and the orientation in the 3D viewport, set the Bone Orientation to true under the display settings of a selected Rigid Body in the Properties pane.

Real-time Information

Default Orientation

As mentioned previously, the orientation axis of a Rigid Body, by default, gets aligned with the global axis when the Rigid Body was first created. After a Rigid Body is created, its orientation can be adjusted by editing the Rigid Body orientation using the Builder pane or by using the GIZMO tools as described in the next section.

Adjusting Rigid Body Pivot Point

There are situations where the desired pivot point location is not at the center of a Rigid Body. The location of a pivot point can be adjusted by assigning it to a marker or by translating along the Rigid Body axis (x,y,z). For most accurate pivot point location, attach a marker on the desired pivot location, set the pivot point to the marker, and apply the translation for precise adjustments. If you are adjusting the pivot point after the capture, in the Edit mode, the Take will need to be auto-labeled again to apply the changes.

Using the Gizmo Tool

Using the gizmo tools from the perspective view options to easily modify the position and orientation of Rigid Body pivot points. You can translate and rotate Rigid Body pivot, assign pivot to a specific marker, and/or assign pivot to a mid-point among selected markers.

• Select Tool (Hotkey: Q): Select tool for normal operations.

• Translate Tool (Hotkey: W): Translate tool for moving the Rigid Body pivot point.

• Rotate Tool (Hotkey: E): Rotate tool for reorienting the Rigid Body coordinate axis.

• Scale Tool (Hotkey: R): Scale tool for resizing the Rigid Body pivot point.

Read through the Gizmo tools page for detailed information.

Setting Pivot Point to a Marker

To assign the pivot point to a marker, first select the pivot point in the Perspective View pane, and CTRL select the marker that you wish to assign to. Then right-click to open the context menu, and in the rigid body section, click Set Pivot Point to Selected Marker.

Translating Pivot Point

To translate the pivot point, access the Rigid Body editing tools in the Builder pane while the Rigid Body is selected. In the Location section, you can input the amount of translation (in mm) that you wish to apply. Note that the translation will be applied along the x/y/z of the Rigid Body orientation axis. Resetting the translation will position the pivot point at the geometric center of the Rigid Body according to its marker positions.

Resetting the Pivot Point

If you wish to reset the pivot point, simply open the Rigid Body context menu in the Perspective pane and click Reset Pivot. The location of the pivot point will be reset back to the center of the Rigid Body again.

Pivot for Spherical Placement

This feature is useful when tracking a spherical object (e.g. ball). The Spherical Pivot Placement feature in the Builder pane will assume that all the Rigid Body markers are placed on the surface of a spherical object, and the pivot point will be calculated and re-positioned accordingly. To do this, select a Rigid Body, access Modify tab in the Builder pane, and click Apply from the Spherical Pivot Placement.

Rigid Body Tracking Data Output

Rigid Body tracking data can be either outputted onto a separate file or streamed to client applications in real-time:

• Captured 6 DoF Rigid Body data can be exported into CSV, FBX, or BVH files. See: Data Export

• You can also use one of the streaming plugins or use NatNet client applications to receive tracking data in real-time. See: NatNet SDK

Additional Features

Export Asset Definitions

Assets can be exported into Motive user profile (.MOTIVE) file if it needs to be re-imported. The user profile is a text-readable file that can contain various configuration settings in Motive; including the asset definitions.

When the asset definition(s) is exported to a MOTIVE user profile, it stores marker arrangements calibrated in each asset, and they can be imported into different takes without creating a new one in Motive. Note that these files specifically store the spatial relationship of each marker, and therefore, only the identical marker arrangements will be recognized and defined with the imported asset.

To export the assets, go to Files tab → Export Assets to export all of the assets in the Live-mode or in the current TAK file. You can also use Files tab → Export Profile to export other software settings including the assets.

Rigid Body Refinement

The Rigid Body refinement tool improves the accuracy of Rigid Body calculation in Motive. When a Rigid Body asset is initially created, Motive references only a single frame for defining the Rigid Body definition. The Rigid Body refinement tool allows Motive to collect additional samples in the live mode for achieving more accurate tracking results. More specifically, this feature improves the calculation of expected marker locations of the Rigid Body as well as the position and orientation of the Rigid Body itself.

Steps

1. Select View from the toolbar at the top, open the Builder pane.

2. Select the Rigid Bodies from the Type dropdown menu.

3. In Live mode, select an existing Rigid Body asset that you wish to refine from the Assets pane.

4. Hold the physical selected Rigid Body at the center of the capture volume so that as many cameras as possible can clearly capture the markers on the Rigid Body.

5. Click Start Refine in the Builder pane.

6. Slowly rotate the Rigid Body to collect samples at different orientations until the progress bar is full.

7. Once all necessary samples are collected, the refinement results will be displayed.

Overview

Like in many other measurement systems, calibration is also essential for optical motion capture systems. During camera calibration, the system computes position and orientation of each camera and amounts of distortions in captured images, and they are used constructs a 3D capture volume in Motive. This is done by observing 2D images from multiple synchronized cameras and associating the position of known calibration markers from each camera through triangulation.

Please note that if there is any change in a camera setup over the course of capture, the system will need to be recalibrated to accommodate for changes. Moreover, even if setups are not altered, calibration accuracy may naturally deteriorate over time due to ambient factors, such as fluctuation in temperature and other environmental conditions. Thus, for accurate results, it is recommended to periodically calibrate the system.

General Steps in Calibration

1. Prepare and optimize the capture volume for setting up a motion capture system.

2. Apply masks to ignore existing reflections in the camera view. Here, also make sure the calibration tools are hidden from the camera views.

3. Collect calibration samples through the wanding process.

4. Review the wanding result and apply calibration.

5. Set the ground plane to complete the system calibration.

Preparing and Optimizing the Setup

System settings used for calibration should be kept unchanged. If camera settings are altered after the calibration, the system would potentially need to be recalibrated. To avoid such inconveniences, it is important to optimize both hardware and software setup before the calibration. First, cameras need to be appropriately placed and configured to fully cover the capture volume. Secondly, each camera must be mounted securely so that they remain stationary during capture. Lastly, Motive's camera settings used for calibration should ideally remain unchanged throughout the capture. Re-calibration will be required if there is any significant modifications to the settings that influence the data acquisition, such as camera settings, gain settings, and Filter Switcher settings. If these settings are modified, it is recommended the system be recalibrated.

Masking

All extraneous reflections or unnecessary markers are ideally removed from the capture volume before calibration. In fact, the system will refuse to calibrate if there are too many reflections other than the calibration wand present in the camera views. However, in certain situations, unwanted reflections or ambient interference could not be removed from the setup. In this case, these irrelevant reflections can be ignored via using the Masking Tool. This tool applies red masks over the extraneous reflections seen from the 2D camera view, and all of the pixels in the masked regions is entirely filtered out. This is very useful when blocking unwanted reflections that could not be removed from the setup. Use the masking tool to remove any extraneous reflections before proceeding to wanding.

Applying Masks

Wanding

The wanding process is the core pipeline that samples calibration data into Motive. A calibration wand is waved in front of the cameras repeatedly, allowing all cameras to see the markers. Through this process, each camera captures sample frames in order to compute their respective position and orientation in the 3D space. There are a number of calibration wands suited for different capture applications.

Wanding Steps

1. Under the OptiWands section, specify the wand that you will be using to calibrate the volume. It is very important to input the matching wand size here. When an incorrect dimension is given to Motive, the calibrated 3D volume will be scaled incorrectly. For example, if you are using CW-500 wand with markers on configuration A, use the 500mm setting. If you are using CW-250 wand, or CW-500 wand with configuration B, please use the 250mm setting.

2. Set the Calibration Type. If you are calibrating a new capture volume, choose Full Calibration.

3. Double check the calibration setting. Once confirmed, press Start Wanding to initiate the wanding process.

4. Start wanding. Bring your calibration wand into the capture volume and start waving the wand gently across the entire capture volume. Draw figure eight with the wand to collect samples at varying orientations, and cover as much space as possible for sufficient sampling. If you wish to start calibrating inside the volume, cover one of the markers and expose it wherever you wish to start wanding. When at least two cameras detect all the three markers while no other reflections are present in the volume, the wand will be recognized, and Motive will start collecting samples. Wanding trails will be shown in colors on the 2D view. A table displaying the status of the wanding process will show up in the Calibration pane to monitor the progress. For best results, wand the volume evenly and comprehensively throughout the volume, covering both low and high elevations.

5. After collecting a sufficient number of samples, press the Calculate button under the Calibration section.

After wanding throughout all areas of the volume, consult the each 2D view from the Camera Preview Pane to evaluate individual camera coverage. Each camera should be thoroughly covered with wand samples. If there are any large gaps, attempt to focus wanding on those to increase coverage. When sufficient amounts of calibration samples are collected by each camera, press Calculate in the Calibration Pane, and Motive will start calculating the calibration for the capture volume. Generally, 2,000 - 5,000 samples are enough.

Prime Series: LED Indicator ring

For Prime series cameras, the LED indicator ring displays the status of the wanding process. As soon as the wanding is initiated, the LED ring will turn dark, and then green lights will fill up around the ring as the camera collects the sample data from the calibration wand.

Eventually, the ring will be filled with green light when sufficient amount of samples are collected. A single LED will glow blue if the calibration wand is detected by the camera, and the clock position of the blue light will indicate the respective wand location in the Camera Preview pane.

For more information, please visit our Camera Status Indicators documentation page.

Calibration Results

After sufficient marker samples have been collected, press Calculate to calibrate using collected samples. The time needed for the calibration calculation varies depending on the number of cameras included in the setup as well as the amount of collected samples.

Immediately after clicking calculate, the samples window will turn into the solver window. It will display the solver stage at the top, followed by the overall result rating and the overall quality selection. The overall result rating is the lowest rating of any one camera in the volume. The overall quality selection shows the current solver quality.

Calibration Result Report

After going through the calculation, a Calibration Result Report will pop up, and detailed information regarding the calibration will be displayed. The Calibration Result is directly related to the mean error, and will update, and the calibration result tiers are (on order from worst to best): Poor, Fair, Good, Great, Excellent, and Exceptional. If the results are acceptable, press Apply to use the result. If not, press cancel and repeat the wanding process. It is recommended to save your calibration file, for later use.

Calibration Results Report

Calibration Summary

After the calculation has completed, you will see cameras displayed in the 3D view pane of Motive. However, the constructed capture volume in Motive will not be aligned with the coordinate plane yet. This is because the ground plane is not set. If calibration results are acceptable, proceed to setting the ground plane.

Calibration Summary

Ground Plane and Origin

The final step of the calibration process is setting the ground plane and the origin. This is accomplished by placing the calibration square in your volume and telling Motive where the calibration square is. Place the calibration square inside the volume where you want the origin to be located and the ground plane to be leveled to. The position and orientation of the calibration square will be referenced for setting the coordinate system in Motive. Align the calibration square so that it references the desired axis orientation.

The longer leg on the calibration square will indicate the positive z axis, and shorter leg will indicate the direction of the positive x axis. Accordingly, the positive y axis will automatically be directed upward in a right-hand coordinate system. Next step is to use the level indicator on the calibration square to ensure the orientation is horizontal to the ground. If any adjustment is needed, rotate the nob beneath the markers to adjust the balance of the calibration square.

If you wish to adjust position and orientation of the global origin after the capture has been taken, you can apply the capture volume translation and rotation from the Calibration pane. After the modification has been applied, new set of 3D data must be reconstructed from the recorded 2D data.

After confirming that the calibration square is properly placed, open the Ground Plane tab from the Calibration Pane. Select the three calibration square markers in the 3D Perspective View. When the markers are selected, press Set Ground Plane to reorient the global coordinate axis in respect to the calibration square. After setting the ground plane, Motive will ask to save the calibration data, CAL.

Vertical offset

The Vertical Offset setting in the Calibration pane is used to compensate for the offset distance between the center of markers on the calibration square and the actual ground. Defining this value takes account of the offset distance and sets the global origin slightly below the markers. Accordingly, this value should correspond to the actual distance between the center of the marker and the lowest tip at the vertex of the calibration square. When a calibration square is detected in Motive, it will recognize the type of the square used and automatically set the offset value. This setting can also be used when you want to place the ground plane at a specific elevation. A positive offset value will place the plane below the markers, and a negative value will place the plane above the markers.

Ground Plane Refinement

Ground Plane Refinement feature is used to improve the leveling of the coordinate plane. To refine the ground plane, place several markers with a known radius on the ground, and adjust the vertical offset value to the corresponding radius. You can then select these markers in Motive and press Refine Ground Plane, and it will refine the leveling of the plane using the position data from each marker. This feature is especially useful when establishing a ground plane for a large volume, because the surface may not be perfectly uniform throughout the plane.

Calibration Files

Calibration files can be used to preserve calibration results. The information from the calibration is exported or imported via the CAL file format. Calibration files reduce the effort of calibrating the system every time you open Motive. These can also be stored within the project so that it can be loaded whenever a project is accessed. By default, Motive loads the last calibration file that was created, this can be changed via the Application Settings.

Note that whenever there is a change to the system setup, these calibration files will no longer be relevant and the system will need to be recalibrated.

Refining Calibration

Continuous Calibration

The continuous calibration feature continuously monitors and refines the camera calibration to its best quality. When enabled, minor distortions to the camera system setup can be adjusted automatically without wanding the volume again. In other words, you can calibrate a camera system only once and you will no longer have to worry about external distortions such as vibrations, thermal expansion on camera mounts, or small displacements on the cameras. For detailed information, read through the Continuous Calibration page.

Enabling/Disabling Continuous Calibration

The Continuous Calibration can be enabled under the Reconstruction tab in the Application Settings.

Disabled

Continuous Calibration is disabled.

Continuous

In this mode, the Continuous Calibration is enabled and Motive is continuously optimizing the camera calibration. This mode will accommodate only the minor changes, such as vibrations, thermal expansions, or minor drifts in positions and orientations of the cameras.

Continuous + Bumped Camera

This feature also allows Motive to continuously monitor the system calibration. Unlike the standard Continuous Calibration, this mode can adjust the system calibration to even drastic changes in positions and orientations of cameras. If you have cameras displaced a lot, set this setting to the bumped camera mode and Motive will accommodate for the change and reposition the bumped camera. For maintaining the calibration quality, just use the continuous mode.

Offline Calibration

When capturing throughout a whole day, temperature fluctuations may degrade calibration quality and you will want to recalibrate the capture volume at different times of the day. However, repeating entire calibration process could be tedious and time-consuming especially with a high camera count setup. In this case, instead of repeating the entire calibration process, you can just record Takes with the wand waves and the calibration square, and use the take to re-calibrate the volume in the post-processing. This offline calibration can save calibration calculation time on the capture day because you can process the recorded wanding take in the post-processing instead. Also, the users can inspect the collected capture data and decide to re-calibrate the recorded Take only when any signs of degraded calibration quality is seen from the captures.

Offline Calibration Steps

1) Capture wanding/ground plane takes. At different times of the day, record wanding Takes that closely resembles the calibration wanding process. Also record corresponding ground plane Takes with calibration square set in the volume for defining the ground plane.

2) Load the recorded Wanding Take. If you wish to re-calibrate the cameras for captured Takes during playback, load the wanding take that was recorded around the same time.

3) Motive: Calibration pane. In the Edit mode, press Start Wanding. The wanding samples from recorded 2D data will be loaded.

4) Motive: Calibration pane. Press Calculate, and wait until the calculation process is complete.

5) Motive: Calibration pane. Apply Result and export the calibration file. File tab → Export Camera Calibration.

6) Load the recorded Ground Plane Take.

7) Open the saved calibration file. With the Ground Plane Take loaded in Motive, open the exported calibration file, and the saved camera calibration will be applied to the ground plane take.

8) Motive: Perspective View. From 2D data of the Ground Plane Take, select the calibration square markers.

9) Motive: Calibration pane: Ground Plane. Set the Ground plane.

10) Motive: Perspective View. Switch back to the Live mode. The recorded Take is now re-calibrated.

Partial Calibration

The partial calibration feature allows you to update the calibration for some selection of cameras in a system. The way this feature works is by updating the position of the selected cameras relative to the already calibrated cameras. This means that you only need to wand in front of the selected cameras as long as there is at least one unselected camera that can also see the wand samples.

This feature is especially helpful for high camera count systems where you only need to adjust a few cameras instead of re-calibrating the whole system. One common way to get into this situation is by bumping into a single camera. Partial calibrations allow you to quickly re-calibrate the single bumped camera that is now out of place. This feature is also useful for those who need to do a calibration without changing the location of the ground plane. The reason the ground plane does not need to be reset is because as long as there is at least one unselected camera Motive can use that camera to retain the position of the ground plane relative to the cameras.

Partial Calibration Steps

1. From the Devices pane, select the camera that has been moved or added.

2. Open the Calibration Pane.

3. Set Calibration Type: In most cases you will want to set this to Full, but if the camera only moved slightly Refine works as well.

4. Specify the wand type.

5. From the Calibration Pane, click Start Wanding. A pop-up dialogue will appear indicating that only selected cameras are being calibrated.

6. Choose Calibrate Selected Cameras from the dialogue window.

7. Wave the calibration wand mainly within the view of the selected cameras.

8. Click Calculate. At this point, only the selected cameras will have their calibration updated.

Active LED Calibration

The OptiTrack motion capture system is designed to track retro-reflective markers. However, active LED markers can also be tracked with appropriate customization. If you wish to use Active LED markers for capture, the system will ideally need to be calibrated using an active LED wand. Please contact us for more details regarding Active LED tracking.

Troubleshooting

A Motive Body license can export tracking data into FBX files for use in other 3D pipelines. There are two types of FBX files: Binary FBX and ASCII FBX.

For more information, please visit Autodesk Motionbuilder's Documentation Support site.

FBX ASCII

Exported FBX files in ASCII format can contain reconstructed marker coordinate data as well as 6 Degree of Freedom data for each involved asset depending on the export setting configurations. ASCII files can also be opened and edited using text editor applications.

FBX ASCII Export Options

FBX Binary

Binary FBX files are more compact than ASCII FBX files. Reconstructed 3D marker data is not included within this file type, but selected Skeletons are exported by saving corresponding joint angles and segment lengths. For Rigid Bodies, positions and orientations at the defined Rigid Body origin are exported.

FBX Binary Export Options

TRC File Format

Captured tracking data can be exported into a Track Row Column (TRC) file, which is a format used in various mocap applications. Exported TRC files can also be accessed from spreadsheet software (e.g. Excel). These files contain raw output data from capture, which include positional data of each labeled and unlabeled marker from a selected Take. Expected marker locations and segment orientation data are not be included in the exported files. The header contains basic information such as file name, frame rate, time, number of frames, and corresponding marker labels. Corresponding XYZ data is displayed in the remaining rows of the file.

CSV Export

Captured tracking data can be exported in Comma Separated Values (CSV) format. This file format uses comma delimiters to separate multiple values in each row, and it can be imported by spreadsheet software or a programming script. Depending on which data export options are enabled, exported CSV files can contain marker data, Rigid Body data, and/or Skeleton data. CSV export options are listed in the following charts:

Errors in the data, Quality Stats

The quality stats display the reliability of associated marker data. Errors per marker lists average displacement between detected markers and expected marker locations within corresponding assets. Marker Quality values rate how well camera rays converged when the respective marker was reconstructed. The value varies from 0 (unstable marker) to 1 (accurate marker).

CSV Header

When the header is disabled, this information will be excluded from the CSV files. Instead, the file will have frame IDs in the first column, time data on the second column, and the corresponding mocap data in the remaining columns.

CSV Headers

Force Plate Data / Analog Data

For Takes containing force plates (AMTI or Bertec) or data acquisition (NI-DAQ) devices, additional CSV files will be exported for each connected device. For example, if you have two force plates and a NI-DAQ device in the setup, total 4 CSV files will be saved when you export the tracking data from Motive. Each of the exported CSV files will contain basic properties and settings at its header, including device information and sample counts. Also, mocap frame rate to device sampling rate ratio is included since force plate and analog data are sampled at higher sampling rates.

Please note that device data is usually sampled at a higher rate then the camera system. In this case, camera samples are collected at the center of the device data samples that were collected in this period. For example, if device data has 9 sub-frame for each camera frame sample, the tracking data will be at every 5th of device data.

• Force Plate Data: Each of the force plate CSV files will contain basic properties such as platform dimensions and mechanical-to-electrical center offset values. The mocap frame number, force plate sample number, forces (Fx/Fy/Fz), moments (Mx, My, Mz), and location of the center of pressure (Cx, Cy, Cz) will be listed below the header.

• Analog Data: Each of the analog data CSV files contains analog voltages from each configured channel.

BVH File Format

Motive can export tracking data in BioVision Hierarchy (BVH) file format. Exported BVH files do not include individual marker data. Instead, a selected skeleton is exported using hierarchical segment relationships. In a BVH file, the 3D location of a primary skeleton segment (Hips) is exported, and data on subsequent segments are recorded by using joint angles and segment parameters. Only one skeleton is exported for each BVH file, and it contains the fundamental skeleton definition that is required for characterizing the skeleton in other pipelines.

General Export Options

BVH Specific Export Options

This page provides basic description of marker labels and instructions on labeling workflow in Motive.

Labeling: Basic Concept

Marker Label

Marker labels are basically software name tags that are assigned to trajectories of reconstructed 3D markers so that they can be referenced for tracking individual markers, Rigid Bodies, or Skeletons. Motive identifies marker trajectories using the assigned labels. Labeled trajectories can be exported individually, or combined together to compute positions and orientations of the tracked objects. In most applications, all of the target 3D markers will need to be labeled in Motive. There are two methods for labeling markers in Motive: auto-labeling and manual labeling, and both labeling methods will be covered in this page.

Monitoring Labels

Labeled or unlabeled trajectories can be identified and resolved from the following places in Motive:

• 3D Perspective Viewport: From the 3D viewport, check the Marker Labels in the visual aids option to view marker labels for selected markers.

• Labels pane: The Labels pane lists out all of the marker labels and corresponding percentage gap for each label. The color of the label also indicates whether if the label is present or missing at the current frame.

• Graph View pane: For frames where the selected label is not assigned to any markers, the timeline scrubber gets highlighted in red. Also, the tracks view of this pane provides a list of labels and their continuity in a captured Take.

Labeling Methods

There are two approaches to labeling markers in Motive:

• Auto-label pipeline: Automatically label sets of Rigid Body markers and Skeleton markers using calibrated asset definitions.

• Manual Label: Manually label individual markers using the Labels pane.

For tracking Rigid Bodies and Skeletons, Motive can use the asset definitions to automatically label associated markers both in real-time and post-processing. The auto-labeler uses references assets that are enabled, or assets that are checked in the Assets pane, to search for a set of markers that matches with the definition and assign pre-defined labels throughout the capture.

There are times, however, when it is necessary to manually label a section or all of a trajectory, either because the markers of a Rigid Body or a Skeleton were misidentified (or unidentified) during capture or because individual markers need to be labeled without using any tracking assets. In these cases, the Labels pane in Motive is used to perform manual labeling of individual trajectories. Manual labeling workflow is supported only in post-processing of capture when a Take file (TAK) has been loaded with 3D data as its playback type. In case of 2D data only capture, the Take must be Reconstructed first in order to assign, or edit, the marker labels in its 3D data. This manual labeling process, along with 3D data editing is typically referred to as post processing of mocap data.

Auto-label

Rigid body and Skeleton asset definitions contain information of marker placements on corresponding assets. This is recorded when the assets are first created, and the auto-labeler in Motive uses them to label a set of reconstructed 3D trajectories that resemble marker arrangements of active assets. Once all of the markers on active assets are successfully labeled, corresponding Rigid Bodies and Skeletons get tracked in the 3D viewport.

The auto-labeler runs in real-time during Live mode and the marker labels get saved onto the recorded TAKs. Running the auto-labeler again in post-processing will basically attempt to label the Rigid Body and Skeleton markers again from the 3D data.

Auto-labeling Steps

From Data pane

1. Select Takes from the Data pane

2. Right-click to bring up the context menu

3. Click reconstruct and auto-label' to process selected Takes. The this pipeline will create a new set of 3D data and auto-label the markers from it.

4. This will label all the markers that matches the corresponding asset definition.

Auto-labeler Settings

The settings for the auto-labeling engine are defined in the Auto-labeler section of the Reconstruction pane. The auto-labeler parameters can be modified during post-processing pipelines, and they can be optimized for stable labeling of markers throughout the Take.

Marker Sets

The Marker Set is a type of assets in Motive. It is the most fundamental method of grouping related markers, and this can be used to manually label individual markers in post-processing of captured data using the Labeling pane. Note that Marker Sets are used for manual labeling only. For automatic labeling during live mode, a Rigid Body asset or a Skeleton asset is necessary.

Since creating rigid bodies, or skeletons, groups the markers in each set and automatically labels them, Marker Sets are not commonly used in the processing workflow. However, they are still useful for marker-specific tracking applications or when the marker labeling is done in pipelines other than auto-labeling. Also, marker sets are useful when organizing and reassigning the labels.

Create MarkerSet

Adding Labels

Labels pane

The Labels pane is used to assign, remove, and edit marker labels in the 3D data. The Tracks View under the Graph View pane can be used in conjunction with the Labels pane to monitor which markers and gaps are associated. The Labels pane is also used to examine the number of occluded gaps in each label, and it can be used along with the Editing Tools for complete post-processing.

For a given frame, all labels are color-coded. For each frame of 3D data, assigned marker labels are shown in white, labels without reconstructions are shown in red, and unlabeled reconstructions are shown in orange; similar to how they are presented in the 3D View.

See the Labels pane page for detailed explanation on each option.

QuickLabel Mode

The QuickLabel mode allows you to tag labels with single-clicks in the view pane, and it is a handy way to reassign or modify marker labels throughout the capture. When the QuickLabel mode is toggled, the mouse cursor switches to a finger icon with the selected label name attached next to it. Also, when the display label option is enabled in the perspective view, all of assigned marker labels will be displayed next to each marker in the 3D viewport, as shown in the image below. Select the marker set you wish to label, and tag the appropriate labels to each marker throughout the capture.

When assigning labels using the Quick Label Mode, the labeling scope is configured from the labeling range settings. You can restrict the labeling operation to apply from the current frame backward, current frame forward, or both depending on the trajectory. You may also restrict labeling operations to apply the selected label to all frames in the Take, to a selected frame range, or to a trajectory 'fragment' enclosed by gaps or spikes. The fragment/spike setting is used by default and this best identifies mislabeled frame ranges and assigns marker labels. See the Labels pane page for details on each feature.

Labeling using the QuickLabel Mode

1. Under the drop-down menu in the Labels pane, select an asset you wish to label.

2. All of the involved markers will be displayed under the columns.

3. From the label list, select unlabeled or mislabeled markers.

4. Inspect the behavior of the selected trajectory and decide whether you want to apply the selected label to frames forward or frames backward or both. This option can be selected from labeling range settings on the Labels pane.

General Labeling Steps

The following section provides the general labeling steps in Motive. Note that the labeling workflow is flexible and alternative approaches to the steps listed in this section could also be used. Utilize the auto-labeling pipelines in combination with the Labels pane to best reconstruct and label the 3D data of your capture.

Using Combined Reconstruction and Auto-label Pipeline

Step 1. In the Data pane, Reconstruct and auto-label the take with all of the desired assets enabled.

Step 2. In the Graph View pane, examine the trajectories and navigate to the frame where labeling errors are frequent.

Step 3. Open the Labels pane.

Step 4. Select an asset that you wish to label.

Step 5. From the label columns, Click on a marker label that you wish to re-assign.

Step 6. Inspect behavior of a selected trajectory and its labeling errors and set the appropriate labeling settings (allowable gap size, maximum spike and applied frame ranges).

Step 7. Switch to the QuickLabel mode (Hotkey: D).

Step 8. On the Perspective View, assign the labels onto the corresponding marker reconstructions by clicking on them.

Step 9. When all markers have been labeled, switch back to the Select Mode.

Using Standalone Reconstruction Pipeline and Auto-label Pipeline Separately

Step 1. Start with 2D data of a captured Take with model assets (Skeletons and Rigid Bodies).

Step 2. Reconstruct and Auto-Label, or just Reconstruct, the Take with all of the desired assets enabled under the Assets pane. If you use reconstruct only, you can skip step 3 and 5 for the first iteration.

Step 3. Examine the reconstructed 3D data, and inspect the frame range where markers are mislabeled.

Step 4. Using the Labels pane, manually fix/assign marker labels, paying attention to your label settings (direction, max gap, max spike, selected duration).

Step 5. Unlabel all trajectories you want to re-auto-label.

Step 6. Auto-Label the Take again. Only the unlabeled markers will get re-labeled, and all existing labels will be kept the same.

Step 7. Re-examine the marker labels. If some of the labels are still not assigned correctly from any of the frames, repeat the steps 3-6 until complete.

Labeling Error Fix

The general process for resolving labeling error is:

1. Identify the trajectory with the labeling error.

2. Determine if the error is a swap, an occlusion, or unlabeled.

3. Resolve the error with the correct tool.

• Swap: Use the Swap Fix tool ( Edit Tools ) or just re-assign each label ( Labels panel ).

  • When manually labeling markers to fix swaps, set appropriate settings for the labeling direction, max spike, and selected range settings.

• Occlusion: Use the Gap Fill tool ( Edit Tools ).

• Unlabeled: Manually label an unlabeled trajectory with the correct label ( Labels panel ).

For more data editing options, read through the Data Editing page.

Sample Scenarios and Tutorial Videos

Sample Scenario 1 :: All Good

When recorded 3D data have been labeled properly and entirely throughout the Take, you will not need to edit marker labels. If you don't have 3D data recorded, you can reconstruct and auto-label the Take to obtain 3D data and label all of the skeleton and rigid body markers. If all of the markers are well reconstructed and there are no significant occlusions, auto-labeled 3D data may be acceptable right away. In this case, you can proceed without post-processing of marker labels.

1. Recorded 3D data has no gaps in the labels, or the Reconstruct and Auto-label works perfectly the first time without additional post-processing.

2. Examine the Take(s). Check the Labeling pane, or the tracks view, to make sure no occlusion exists within the capture, and all markers are consistently labeled.

3. Done.

Sample Scenario 2 :: Labeling errors in the middle of a Take

When skeleton markers are mislabeled only within specific frame ranges of a Take, you will have to manually re-label the markers. This may occur when a subject performs dynamic movements or come into contact with another object during the recorded Take. After correcting the mislabeled markers, you can also use the auto-labeler to assign remaining missing labels.

1. Start with recorded 3D data or Reconstruct and auto-label the Take to obtain newly labeled 3D data.

2. Inspect the Take to pick out the frame ranges with bad tracking.

3. If markers are mislabeled during majority of the capture, unlabel all markers from the entire capture by right-clicking on the Take in Data Management pane and click Delete Marker Labels. You can do this on selected frame ranges as well.

4. Scrub the timeline to a frame just before the bad tracking frame range.

5. Using the Labeling pane, manually label the skeleton. Depending on the severity of the mislabels, you can either label the entire skeleton or just the key segments starting from the hip.

6. Scrub the timeline to a frame after the bad tracking frame range.

7. Manually label the same skeleton.

8. Auto-label the Take.

9. Check the frames again and correct any remaining mislabels using the Labeling pane.

Sample Scenario 3 :: Skeletons never acquire perfectly throughout a Take

For Take(s) where skeletons are never perfectly tracked and the markers are consistently mislabeled, you will need to manually assign the correct labels for the skeleton asset(s). Situations like this could happen when the skeleton(s) are never in an easily trackable pose throughout the Take (e.g. captures where the actors are rolling on the ground). It is usually recommended that all skeleton ‘’Takes’’’ start and end with T-pose in order to easily distinguish the skeleton markers.

This also helps the skeleton solver to correctly auto-label the associated markers; however, in some cases, only specific section of a Take needs be trimmed out, or including the calibration poses might not be possible. Manually assigning labels can help the auto-labeler to correctly label markers and have skeletons acquire properly in a Take.

You will get best results if you manually label the entire skeleton, but doing so can be time-consuming. You can also label only the mislabeled segment or the key segment (hip bone) and run the auto-labeler to see if it correctly assigns the labels with the small help.

1. Start with recorded 3D data or Reconstruct the Take.

2. At a certain point of the Take (usually at a frame where you can best identify the pose of the skeleton), use the Labeling pane to manually assign the marker labels for skeletons that are not labeling correctly. Depending on the severity of the mislabels, you can either label the entire skeleton or only the key segments starting from the hip.

3. After manually assigning the labels, auto-label the Take. Make sure the corresponding assets are enabled in the Assets pane.

4. Check to see if all markers are correctly assigned throughout the take. If not, re-label or unlabel, any mislabeled markers and run auto-label again if needed.

Sample Scenario 4 :: Mislabeling/unlabeling of a marker due to occlusions

Marker occlusions can be critical to the auto-labeling process. After having a gap for multiple frames, occluded markers can be unlabeled entirely, or nearby reconstructions can be mistakenly recognized as the occluded marker and result in labeling swaps or mislabels. Skeleton and rigid body asset definitions may accommodate labeling for such occlusions, but in some cases, labeling errors may persist throughout the Take. The following steps can be used to re-assign the labels in this case.

If tracked markers are relatively stationary during the occluded frames, you may want to increase the Maximum Marker Label Gap value under the Auto-Labeler settings in the Reconstruction pane to allow the occluded marker to maintain its label after auto-labeling the Take. However, note that adjusting this setting will not be useful if the marker is moving dynamically beyond the Prediction Radius (mm) settings during occlusion.

1. Start with recorded 3D data or Reconstruct and auto-label the Take

2. Examine through the Take, and go to a frame where markers are mislabeled right after an occlusion.

5. Using the Quick Label Mode, correct the labeling errors.

6. Move onto next occluded frames. When the marker reappears, correct the labels.

7. After correcting the labels, Auto-label the Take again.

8. Use the Fill Gaps tool in the Editing tools to interpolate the occluded trajectories.

This page provides information and instructions on how to utilize the Probe Measurement Kit.

Overview

Measurement probe tool utilizes the precise tracking of OptiTrack mocap systems and allows you to measure 3D locations within a capture volume. A probe with an attached Rigid Body is included with the purchased measurement kit. By looking at the markers on the Rigid Body, Motive calculates a precise x-y-z location of the probe tip, and it allows you to collect 3D samples in real-time with sub-millimeter accuracy. For the most precise calculation, a probe calibration process is required. Once the probe is calibrated, it can be used to sample single points or multiple samples to compute distance or the angle between sampled 3D coordinates.

Measurement kit includes:

• Measurement probe

• Calibration block with 4 slots, with approximately 100 mm spacing between each point.

Using the Probe

This section provides detailed steps on how to create and use the measurement probe. Please make sure the camera volume has been calibrated successfully before creating the probe. System calibration is important on the accuracy of marker tracking, and it will directly affect the probe measurements.

Step 1: Probe Calibration

Creating a probe using the Builder pane

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

2. Bring the probe out into the tracking volume and create a Rigid Body from the markers.

3. Under the Type drop-down menu, select Probe. This will bring up the options for defining a Rigid Body for the measurement probe.

4. Select the Rigid Body created in step 2.

5. Place and fit the tip of the probe in one of the slots on the provided calibration block.

6. Note that there will be two steps in the calibration process: refining Rigid Body definition and calibration of the pivot point. Click Create button to initiate the probe refinement process.

7. Slowly move the probe in a circular pattern while keeping the tip fitted in the slot; making a cone shape overall. Gently rotate the probe to collect additional samples.

8. After the refinement, it will automatically proceed to the next step; the pivot point calibration.

9. Repeat the same movement to collect additional sample data for precisely calculating the location of the pivot or the probe tip.

10. When sufficient samples are collected, the pivot point will be positioned at the tip of the probe and the Mean Tip Error will be displayed. If the probe calibration was unsuccessful, just repeat the calibration again from step 4.

11. Once the probe is calibrated successfully, a probe asset will be displayed over the Rigid Body in Motive, and live x/y/z position data will be displayed under the Probe pane.

Step 2: Sample Collection

Using the Probe pane for sample collection

1. Under the Tools tab, open the Probe pane.

2. Place the probe tip on the point that you wish to collect.

3. Click Take Sample on the Measurement pane.

4. A Virtual Reference point is constructed at the location and the coordinates of the point are displayed in the Probe Pane. The points location can be exported from the Probe Pane as a .CSV file.

5. Collecting additional samples will provide distance and angles between collected samples.

Set Origin and Set Orientation

You can also use the probe samples to reorient the coordinate axis of the capture volume. The set origin button will position the coordinate space origin at the tip of the probe. And the set orientation option will reorient the capture space by referencing to three sample points.

Export Samples

As the samples are collected, their coordinate data will be written out into the CSV files automatically into the OptiTrack documents folder which is located in the following directory: C:\Users\[Current User]\Documents\OptiTrack. 3D positions for all of the collected measurements and their respective RMSE error values along with distances between each consecutive sample point will be saved in this file.

Also, If needed, you can trigger Motive to export the collected sample coordinate data into a designated directory. To do this, simply click on the export option on the Probe pane.

Real-time Streaming

The location of the probe tip can also be streamed into another application in real-time. You can do this by data-streaming the probe Rigid Body position via NatNet. Once calibrated, the pivot point of the Rigid Body gets positioned precisely at the tip of the probe. The location of a pivot point is represented by the corresponding Rigid Body x-y-z position, and it can be referenced to find out where the probe tip is located.

Overview

The Data Streaming settings can be found by selecting the by selecting View > Data Streaming Pane.

Streaming in Motive

• Select the network interface address for streaming data.

• Select desired data types to stream under streaming options.

• When streaming skeletons, set the appropriate bone naming convention for client application.

• Check Broadcast Frame Data at the top.

• Configure streaming settings and designate the corresponding IP address from client applications

• Stream live or playback captures

Streaming IP Address

Streaming Options

Before starting to broadcast data onto the selected network interface, define which data types to stream. Under streaming options, there are settings where you can include or exclude specific data types and syntax. Set only the necessary criteria to true. For most applications, the default settings will be appropriate.

Bone Naming Convention

When streaming skeleton data, bone naming convention formats annotations for each segment when data is streamed out. Appropriate convention should be configured to allow client application to properly recognize segments. For example, when streaming to Autodesk pipelines, the naming convention should be set to FBX.

Coordinate System Convention

NatNet Streaming

NatNet is a client/server networking protocol which allows sending and receiving data across a network in real-time. It utilizes UDP along with either Unicast or Multicast communication for integrating and streaming reconstructed 3D data, rigid body data, and skeleton data from OptiTrack systems to client applications. Within the API, a class for communicating with OptiTrack server applications is included for building client protocols. Using the tools provided in the NatNet API, capture data can be used in various application platforms. Please refer to the NatNet User Guide For more information on using NatNet and its API references.

Remote Triggering

XML Triggering Port: Command Port (Advanced Network Settings) + 2. This defaults to 1512 (1510 + 2).Tip: Within the NatNet SDK sample package, there is are simple applications (BroadcastSample.cpp (C++) and NatCap (C#)) that demonstrates a sample use of XML remote trigger in Motive.

XML syntax for the start / stop trigger packet

Capture Start Packet

Capture Stop Packet

Streaming Protocols/Plugins

Tracking Bar Coordinate System

If you wish to change the location and orientation of the global axis, you can use the Coordinate Systems Tool which can be found under the Tools tab.

Coordinate Systems Tool

Adjusting the Coordinate System Steps

1. First set place the calibration square at the desired origin.

2. [Motive] Open the Coordinate System Tools pane under the Tools tab.

4. [Motive] Click the Set Ground Plane button from the Coordinate System Tools pane, and the global origin will be adjusted.

The Motive Batch Processor is a separate stand-alone Windows application, built on the new NMotive scripting and programming API, that can be utilized to process a set of Motive Take files via IronPython or C# scripts. While the Batch Processor includes some example script files, it is primarily designed to utilize user-authored scripts.

Initial functionality includes scripting access to file I/O, reconstructions, high-level Take processing using many of Motive's existing editing tools, and data export. Upcoming versions will provide access to track, channel, and frame-level information, for creating cleanup and labeling tools based on individual marker reconstruction data.

Motive Batch Processor Scripts make use of the NMotive .NET class library, and you can also utilize the NMotive classes to write .NET programs and IronPython scripts that run outside of this application. The NMotive assembly is installed in the Global Assembly Cache and also located in the assemblies sub-directory of the Motive install directory. For example, the default location for the assembly included in the 64-bit Motive installer is:

C:\Program Files\OptiTrack\Motive\assemblies\x64

The full source code for the Motive Batch Processor is also installed with Motive, at:

C:\Program Files\OptiTrack\Motive\MotiveBatchProcessor\src

You are welcome to use the source code as a starting point to build your own applications on the NMotive framework.

Use

Requirements

• A batch processor script using the NMotive API. (C# or IronPython)

• Take files that will be processed.

Steps

2. First, select and load a Batch Processor Script. Sample scripts for various pipelines can be found in the [Motive Directory]\MotiveBatchProcessor\ExampleScripts\ folder.

3. Load the captured Takes (TAK) that will be processed using the imported scripts.

4. Click Process Takes to batch process the Take files.

Reconstruction Pipeline

Class Reference

A class reference in Microsoft compiled HTML (.chm) format can be found in the Help sub-directory of the Motive install directory. The default location for the help file (in the 64-bit Motive installer) is:

C:\Program Files\OptiTrack\Motive\Help\NMotiveAPI.chm

C# Scripts

The Motive Batch Processor can run C# and IronPython scripts. Below is an overview of the C# script format, as well as an example script.

C# Script Format

A valid Batch Processor C# script file must contain a single class implementing the ItakeProcessingScript interface. This interface defines a single function:

Result ProcessTake( Take t, ProgressIndicator progress ).

Result, Take, and ProgressIndicator are all classes defined in the NMotive namespace. The Take object t is an instance of the NMotive Take class. It is the take being processed. The progress object is an instance of the NMotive ProgressIndicator and allows the script to update the Batch Processor UI with progress and messages. The general format of a Batch Processor C# script is:

C# Example

In the [Motive Directory]\MotiveBatchProcessor\ExampleScripts\ folder, there are multiple C# (.cs) sample scripts that demonstrate the use of the NMotive for processing various different pipelines including tracking data export and other post-processing tools. Note that your C# script file must have a '.cs' extension.

Included sample script pipelines:

• ExporterScript - BVH, C3D, CSV, FBXAscii, FBXBinary, TRC

• TakeManipulation - AddMarker, DisableAssets, GapFill, MarkerFilterSCript, ReconstructAutoLabel, RemoveUnlabeledMarkers, RenameAsset

IronPython Scripts

IronPython Script Format

Your IronPython script file must import the clr module and reference the NMotive assembly. In addition, it must contain the following function:

def ProcessTake(Take t, ProgressIndicator progress)

The following illustrates a typical IronPython script format.

IronPython Script Example

In the [Motive Directory]\MotiveBatchProcessor\ExampleScripts\ folder, there are sample scripts that demonstrate the use of the NMotive for processing various different pipelines including tracking data export and other post-processing tools. Note that your IronPython script file must have a '.cs' extension.

Recorded audio files can be played back from a captured Take or be exported into a WAV audio files. This page details how to record and playback audio in Motive. Before using an audio input device (microphone) in Motive, first make sure that the device is properly connected and configured in Windows.

Audio Recording/Playback

Audio Settings

In Motive, audio recording and playback settings can be accessed from the tab → Audio Settings.

Audio Recording Steps

1. In Motive, open the Audio Settings, and check the box next to Enable Capture.

2. Select the audio input device that you want to use.

3. Press the Test button to confirm that the input device is properly working.

4. Make sure the device format of the recording device matches the device format that will be used in the playback devices (speakers and headsets). This is very important as the recorded audio would not playback if these formats do not match. Most speakers have at least 2 channels, so an input device with 2 channels should be used for recording.

5. Capture the Take.

Audio Playback Steps

1. In Motive, open a Take that includes audio recordings.

2. To playback recorded audio from a Take, check the box next to Enable Playback.

3. Select the audio output device that you will be using.

4. Make sure the configurations in Device Format closely matches the Take Format. This is elaborated further in the section below.

5. Play the Take.

Device Format

In order to playback audio recordings in Motive, audio format of recorded sounds MUST match closely with the audio format used in the output device. Specifically, communication channels and frequency of the audio must match. Otherwise, recorded sound will not be played back.

The recorded audio format is determined by the format of a recording device that was used when capturing Takes. However, audio formats in the input and output devices may not always agree. In this case, you will need to adjust the input device properties to match the take.

Device's audio format can be configured under the Sound settings in Windows. In Sound settings (accessed from Control Panel), select the recording device, click on Properties, and the default format can be changed under the Advanced Tab, as shown in the image below.

Audio Export

External Audio Capture

There are a variety of different programs and hardware that specialize in audio capture. A not very exhaustive list of examples can be seen below.

• Tentacle Sync TRACK E

• Adobe Premiere

• Avid Media Composer

• Etc...

In order to capture audio using a different program, you will need to connect both the motion capture system (through the eSync) and the audio capture device to timecode data (and possibly genlock data). You can then use the timecode information to synchronize the two sources of data for your end product.

Suggested Capture Devices

The following devices are internally tested and should work for most use cases for reference audio only:

• AT2020 USB

• MixPre-3 II Digital USB Preamp

This page covers different video modes that are available on the OptiTrack cameras. Depending on the video mode that a camera is configured to, captured frames are processed differently, and only the configured video mode will be recorded and saved in Take files.

Video Types

Video types, or image-processing modes, available in OptiTrack Cameras

There are different video types, or image-processing modes, which could be used when capturing with OptiTrack cameras. Dending on the camera model, the available modes vary slightly. Each video mode processes captured frames differently at both camera hardware and software level. Furthermore, precision of the capture and required amount of CPU resources will vary depending on the configured video type.

The video types are categorized into either tracking modes (object mode and precision mode) and reference modes (MJPEG and raw grayscale). Only the cameras in the tracking modes will contribute to the reconstruction of 3D data.

Object Mode

(Tracking Mode) Object mode performs on-camera detection of centroid location, size, and roundness of the markers, and then, respective 2D object metrics are sent to the host PC. In general, this mode is best recommended for obtaining the 3D data. Compared to other processing modes, the Object mode provides smallest CPU footprint and, as a result, lowest processing latency can be achieved while maintaining the high accuracy. However, be aware that the 2D reflections are truncated into object metrics in this mode. The Object mode is beneficial for Prime Series and Flex 13 cameras when lowest latency is necessary or when the CPU performance is taxed by Precision Grayscale mode (e.g. high camera counts using a less powerful CPU).

Supported Camera Models: Prime/PrimeX series, Flex 13, and S250e camera models.

Precision Mode

(Tracking Mode) Precision Mode performs on-camera detection of marker reflections and their centroids. These centroid regions of interests are sent to the PC for additional processing and determination of the precise centroid location. This provides high-quality centroid locations but is very computationally expensive and is only recommended for low to moderate camera count systems for 3D tracking when the Object Mode is unavailable.

Supported Camera Models: Flex series, Tracking Bars, S250e, Slim13e, and Prime 13 series camera models.

MJPEG grayscale Mode

(Reference Mode) The MJPEG -compressed grayscale mode captures grayscale frames, compressed on-camera for scalable reference video capabilities. Grayscale images are used only for reference purpose, and processed frames will not contribute to the reconstruction of 3D data. The MJPEG mode can run at full frame rate and be synchronized with tracking cameras.

Supported Camera Models: All camera models

Raw grayscale

(Reference Mode) Processes full resolution, uncompressed, grayscale images. The grayscale mode is designed to be used only for reference purposes, and processed frames will not contribute to the reconstruction of 3D data. Because of the high bandwidth associated with sending raw grayscale frames, this mode is not fully synchronized with other tracking cameras and they will run at lower frame rate. Also, raw grayscale videos cannot be exported out from a recording. Use this video mode only for aiming and monitoring the camera views for diagnosing tracking problems.

Supported Camera Models: All camera models.

Switching Video Types

From Camera Properties

From Viewports

From Perspective View

In the perspective view, right-click on a camera from the viewport and set the camera to the desired video mode.

From Cameras View

In the cameras view, right-click on a camera view and change the video type for the selected camera.

Reference Videos

Compared to object images that are taken by non-reference cameras in the system, grayscale videos are much bigger in data size, and recording reference video consumes more network bandwidth. High amount data traffic can increase the system latency or cause reductions in the system frame rate. For this reason, we recommend setting no more than one or two cameras to the reference mode. Also, instead of using raw grayscale video, compressed MJPEG grayscale video can be recorded to reduce the data traffic. Reference views can be observed from either the Camera Preview pane or Reference View pane.

View From Selection

The API reports "world-space" values for markers and rigid body objects at each frame. It is often desirable to convert the coordinates of points reported by the API from the world-space (or global) coordinates into the local space of the rigid body. This is useful, for example, if you have a rigid body that defines the world space that you want to track markers within.

Rotation values are reported as both quaternions, and as roll, pitch, and yaw angles (in degrees). Quaternions are a four-dimensional rotation representation that provide greater mathematical robustness by avoiding "gimbal" points that may be encountered when using roll, pitch, and yaw (also known as Euler angles). However, quaternions are also more mathematically complex and are more difficult to visualize, which is why many still prefer to use Euler angles.

There are many potential combinations of Euler angles so it is important to understand the order in which rotations are applied, the handedness of the coordinate system, and the axis (positive or negative) that each rotation is applied about.

These are the conventions used in the API for Euler angles:

• Rotation order: XYZ

• All coordinates are *right-handed*

• Pitch is degrees about the X axis

• Yaw is degrees about the Y axis

• Roll is degrees about the Z axis

• Position values are in millimeters

To create a transform matrix that converts from world coordinates into the local coordinate system of your chosen rigid body, you will first want to compose the local-to-world transform matrix of the rigid body, then invert it to create a world-to-local transform matrix.

To compose the rigid body local-to-world transform matrix from values reported by the API, you can first compose a rotation matrix from the quaternion rotation value or from the yaw, pitch, and roll angles, then inject the rigid body translation values. Transform matrices can be defined as either "column-major" or "row-major". In a column-major transform matrix, the translation values appear in the right-most column of the 4x4 transform matrix. For purposes of this article, column-major transform matrices will be used. It is beyond the scope of this article, but it is just as feasible to use row-major matrices by transposing matrices.

In general, given a world transform matrix of the form: M = [ [ ] Tx ] [ [ R ] Ty ] [ [ ] Tz ] [ 0 0 0 1 ]

where Tx, Tz, Tz are the world-space position of the origin (of the rigid body, as reported from the API), and R is a 3x3 rotation matrix composed as: R = [ Rx (Pitch) ] * [ Ry (Yaw) ] * [ Rz (Roll) ]

where Rx, Ry, and Rz are 3x3 rotation matrices composed according to:

A handy trick to know about local-to-world transform matrices is that once the matrix is composed, it can be validated by examining each column in the matrix. The first three rows of Column 1 are the (normalized) XYZ direction vector of the world-space X axis, column 2 holds the Y axis, and column 3 is the Z axis. Column 4, as noted previously, is the location of the world-space origin. To convert a point from world coordinates (coordinates reported by the API for a 3D point anywhere in space), you need a matrix that converts from world space to local space. We have a local-to-world matrix (where the local coordinates are defined as the coordinate system of the rigid body used to compose the transform matrix), so inverting that matrix will yield a world-to-local transformation matrix. Inversion of a general 4x4 matrix can be slightly complex and may result in singularities, however we are dealing with a special transform matrix that only contains rotations and a translation. Because of that, we can take advantage of the method shown here to easily invert the matrix:

Once the world matrix is converted, multiplying it by the coordinates of a world-space point will yield a point in the local space of the rigid body. Any number of points can be multiplied by this inverted matrix to transform them from world (API) coordinates to local (rigid body) coordinates.

The API includes a sample (markers.sln/markers.cpp) that demonstrates this exact usage.

Hotkeys can be viewed and customized from the panel. The below chart lists only the commonly used hotkeys. There are also other hotkeys and unassigned hotkeys, which are not included in the chart below. For a complete list of hotkey assignments, please check the in Motive.

Motive Default Hotkey Settings

This page provides an explanation on some of the settings that affect how the 3D tracking data is obtained. Most of the related settings can be found under the Live Pipeline tab in the . A basic understanding of this process will allow you to fully utilize Motive for analyzing and optimizing captured 3D tracking data. With that being said, we do not recommend changing these settings as the default settings should work well for most tracking applications.

Reconstruction: Basic Concept

• THR setting under camera properties

Reconstruction is a process of deriving 3D points from 2D coordinates obtained by captured camera images. When multiple synchronized images are captured, 2D centroid locations of detected marker reflections are triangulated on each captured frame and processed through the solver pipeline in order to be tracked. This process involves trajectorization of detected 3D markers within the calibrated capture volume and the booting process for the tracking of defined assets.

For real-time tracking in Live mode, the settings for this pipeline can be configured from the Live-Pipeline tab in the . For post-processing recorded files in Edit mode, the solver settings can be accessed under corresponding . Note that optimal configurations may vary depending on capture applications and environmental conditions, but for most common applications, default settings should work well.

In this page, we will focus on the and the , which are the key settings that have direct effects on the reconstruction outcome.

Camera Settings

Enable Reconstruction

• To oscillate between camera video types in Motive, click the camera video type icon under Mode in the Devices pane.

Threshold Setting

Live Pipeline Settings

Camera Filter - Software

When a frame of image is captured by a camera, the 2D camera filter is applied. This filter works by judging on the sizes and shapes of the detected reflections or IR illuminations, and it determines which ones can be accepted as markers. Please note that the camera filter settings can be configured in Live mode only because this filter is applied at the hardware level when the 2D frames are first captured. Thus, you will not be able to modify these settings on a recorded Take as the 2D data has already been filtered and saved; however, when needed, you can increase the threshold on the filtered 2D data and perform post-processing reconstruction to recalculate 3D data from the 2D data.

Min/Max Thresholded Pixels

The Min/Max Thresholded Pixels settings determine lower and upper boundaries of the size filter. Only reflections with pixel counts within the boundaries will be considered as marker reflections, and any other reflections below or above the defined boundary will be filtered out. Thus, it is important to assign appropriate values to the minimum and maximum thresholded pixel settings.

For example, in a close-up capture application, marker reflections appear bigger on camera's view. In this case, you may want to lower the maximum threshold value to allow reflections with more thresholded pixels to be considered as marker reflections. For common applications, however, the default range should work fine.

Circularity

Object mode vs. Precision Mode

Marker Rays