OptiTrack - FAQs

1. Fundamentals

In an optical motion capture system, multiple synchronized cameras are installed around the target capture volume, and 2D images are captured from each camera. 2D positions are calculated, and the overlapping position data are compared to compute the 3D positions via triangulation.

Optical motion capture systems obtain the data through detecting emitted or reflected light. Therefore, it is recommended to minimize the ambient lighting to reduce interferences, which includes sunlight and extraneous illumination or reflection sources.

The ideal camera placement may vary depending on the capture application. Generally, it is beneficial to have cameras arranged around the periphery of the volume at varying heights so that each camera captures a distinct view of the volume.

Take a look at the volume layouts located on the

Build Your Own

page for additional guidance about placing your cameras.

The Primex 41 is capable of tracking a 16 mm mocap marker from a distance of 100 feet.

Note that the trackable range in optical motion capture depends on many variables, mostly on the marker size, the marker type, and the capture environment settings. Our Primex series cameras are equipped with a powerful LED illumination array and a high resolution imager which allows tracking at very long distances.

2. Motion capture

OptiTrack camera systems have the fidelity to capture all types of human body and rigid body movements, including both subtle and fast motions. Rigid body movement can be captured when at least three markers are visible. Facial movement and skeletons can be tracked as long as a sufficient number of markers are visible. Movements that involve excessive occlusion of markers may require adjustment to the marker set and camera placement. More dynamic motions will benefit from a larger capture volume to work within.

Yes, props and skeletons can be captured at the same time.

With an optimized capture setup and an Unlimited license, an OptiTrack system can track up to 12 actors with props. It is important to note that with a basic license its only 3 skeletons, however, this is a license limitation not a software limitation.

Note that the number of people or objects that can be tracked with an optical motion capture system is based on multiple influencing factors, which include the capture environment and the system setup specification. Depending on how these factors are optimized, the maximum number of trackable assets may vary substantially. For this reason, it is difficult to state a maximum number. The

Build Your Own

feature on our website will provide some guidelines which are recommended minimums for the system setup and number of actors that can be tracked.

If you wish to track higher numbers of rigid bodies or people than the number indicated in

Build Your Own

, consult one of our

Sales Engineers

to find out which system setup is appropriate for a particular application.

Skeleton Tracking

With an optimized capture setup, an OptiTrack system can track 84 rigid bodies at a time, however, this number is not exhaustive. This is just how many rigid bodies we were able to test at one time. This number is potentially higher.

Build Your Own

feature on our website will provide some guidelines which are recommended minimums for the system setup and number of actors that can be tracked.

If you wish to track higher number of rigid bodies or people than the number indicated in

Build Your Own

, consult one of our

Sales Engineers

to find out which system setup is appropriate for a particular application.

Rigid Body Tracking

Yes, outdoor tracking is possible with OptiTrack camera systems. Our Prime series cameras feature high-powered LED strobes which are suited for detection of passive (reflective) markers in strong sunlight. To further improve marker visibility and tracking range, active (LED) markers can be used in place of passive markers.

Outdoor Tracking

With a Motive Body license, there are standard marker sets that create a skeletal model which target both finger and body movements. Here, the finger tracking is done by analyzing the kinematics of the hand and estimating the pose of each finger. For accurate finger tracking performance, markers can be attached directly to the fingers using skin adhesives. A full line of adhesive markers are available in our webstore. Motive is also compatible with Manus, a third-party producer of motion trackable gloves. For more information, please visit the

Manus website

Manus Glove Setup

Yes, performance capture is supported with a Motive Body license. OptiTrack cameras enable users to capture fine details from facial expressions while simultaneously tracking the body motion.

The 3D location of markers can be resolved with sub-millimeter accuracy with an optimal capture volume size and camera configuration.

When connected to the OptiHub2 or the eSync2, cameras can synchronize their exposure timing to external sources. Common uses are to synchronize capture data with software or hardware controls such as force plates, shutter glasses, timecode generators, or head mounted displays.

External Device Setup OptiHub2

External Device Setup eSync2

Yes, our motion capture cameras are capable of frame rates up to 360 Hz, making non-smeared motion tracking for most objects possible. For example, we regularly track swinging golf clubs which travel up to 125 mph.

For most applications, 3D data is processed in real-time at the full system frame rate. For data intensive applications, the system processes the 3D data in real-time as quickly as possible, resulting in live 3D data on most but not all frames.

For all applications, recorded data can be processed for all captured frames regardless of the frame rate.

3. Camera Settings

Yes, all OptiTrack cameras have the capability of transmitting the entire grayscale frame to the host PC. Motive or the Camera SDK provides the ability to select the video mode and access the data. Furthermore, MJPEG grayscale video is also supported for transmitting downsampled images in order to reduce network traffic.

Raw grayscale and MJPEG video modes are useful for recording reference videos and adjusting focus and aiming of the camera.

Raw grayscale video mode from the camera allows transmitting a full resolution grayscale image. Raw grayscale images consume large amounts of network bandwidth. For this reason, raw grayscale video mode is more useful for focus and aiming of cameras.

For reference video applications, MJPEG grayscale mode transmits compressed images which reduces the bandwidth for recording video. This guarantees that video will be captured at the full camera frame rate under most conditions.

The IR intensity setting is now an on/off setting. Please adjust the exposure setting to adjust the brightness of the image in the IR spectrum.

The Exposure value in the camera setting controls how long the shutter remains open, per frame. Increasing the Exposure value allows more light in, creating a brighter image that can increase visibility for small and dim markers. However, setting the Exposure too high can introduce merging of adjacent markers and marker blurring—all of which can negatively impact the tracking quality.

The Threshold setting determines a minimum brightness of a pixel for it to be considered in the calculation of a 2D object. All pixels with a brightness below the Threshold setting are ignored.

Increasing the Threshold value can help filter light interference from non-markers in the camera view. Lowering the Threshold value can allow less-visible markers (e.g. small markers, worn markers, and markers at longer distances from the camera) to be seen by the camera.

The Frame Rate (FPS) value determines the number of images a camera will capture per second. A higher FPS value will record more data within a given time. A lower FPS value will allow for higher exposure values for brighter images and will also reduce network traffic.

The maximum frame rate of the system will be limited to that of the camera with the lowest maximum frame rate.

Increasing the Gain setting amplifies the brightness of the entire image and it can be used to improve the tracking at very long distances. Specifically, changing the Gain setting applies a multiplier to the brightness of every pixel in the image before applying the Threshold setting.

Properties Pane: Camera

4. Motive and Data Streaming

OptiTrack cameras use Motive to collect and process motion capture data. There are two license types of Motive capable of capturing data from the camera system: Motive:Tracker and Motive:Body.

Motive:Tracker is capable of tracking rigid bodies. Motive:Body supports both skeletal tracking and rigid body tracking.

Motive:Edit is available for editing and playback purposes only.

Installation and Activation

Yes, Motive:Body supports real-time processing with skeleton solving. This includes the ability to stream live skeleton data to other software in real-time using a variety of streaming protocols.

Motive distinguishes different objects and people by recognizing the uniqueness of the marker arrangement. When an asset is created, the spatial relationships between markers are recorded and used to recognize and differentiate multiple people or objects. When two or more objects or people are about the same size and shape, it is beneficial to offset one or more markers (e.g. waist markers) so Motive can differentiate between them. Skeleton markersets in Motive have optional magenta markers. These markers are in addition to the required white markers and can be placed uniquely to differentiate two actors/skeletons from each other.

Marker Sets

Motive supports highly optimized skeleton templates for various applications. Moreover, edit options for adding and removing extra markers to or from the template skeleton are available, which allows partial customization of marker sets.

Skeleton Tracking

Motive:Tracker supports exporting tracking data in CSV and C3D format. Motive:Body supports exporting CSV and C3D file format. It also exports FBX (Binary and ASCII), BVH, and TRC. Furthermore, the capture data can also be streamed to other software utilizing supported plugins and data-streaming pipelines.

Date Export

Motive will run on Windows 8.1 or later. MacOS is not currently supported. Ubuntu and Fedora distros are able run NatNet and have the ability to receive streaming data from a Windows machine running Motive.

Installation and Activation

The Camera SDK provides access to the most fundamental data, such as grayscale images and 2D object information, from each camera. Available data includes the sub-pixel weighed center (X, Y) position and area of the marker on the imager in pixels.

Motive reconstructs 3D points from 2D data collected from each camera, and both the 3D position and orientation for skeletons and rigid bodies can be calculated.

Motive:Tracker provides access to the rigid body data. Motive:Body provides access to both skeletal data and rigid body data.

Data Export

The information available for markers in the Camera SDK is the sub-pixel weighed center X, Y position and area of the marker on the imager in pixels.

In Motive, reconstructed 3D data with X, Y, Z coordinate information, along with rotation X, Y, and Z information, is available.

Reconstruction and 2D Mode

NatNet does not support streaming over the Internet. A direct ethernet cable connection or private LAN/hub for the client and server are the preferred configurations. Streaming over local LANs is also supported by NatNet, however that setup may generate unwanted traffic for other users on the network.

The Motive Batch Processor is a stand-alone application built on the NMotive scripting and programming API. It allows scripted access to file input and output, reconstruction and auto-labeling, high-level processing using many of Motive's existing editing tools, and data export. The Motive Batch Processor is designed to utilize user-authored scripts for custom applications.

Sample script files and a class reference file for the Motive Batch Processor can be found in the Motive folder.

Sample script files: [MotiveInstallDirectory]\MotiveBatchProcessor\ExampleScripts

Class reference file: [MotiveInstallDirectory]\Help

Motive Batch Processor

Motive provides FBX/BVH/C3D file export, which is compatible with many common 3D rendering and animation packages (i.e. Maya, 3D Studio Max, MotionBuilder). Real-time streaming

plugins

are also available for MotionBuilder and 3D Studio Max. 3D streaming protocols are also supported for other applications: Trackd, VRPN, and the OptiTrack

NatNet

protocol.

The

NatNet SDK

is a client/server networking SDK designed for sending and receiving motion capture data across networks. Customers who wish to write their own plugins or applications can make the motion capture data available to other applications 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.

Autodesk MotionBuilder Plugin

Yes, recorded reference videos can be exported into AVI video files. Note that these files may not be playable on Windows Media Player. Use a robust media player (i.e. VLC) for playing back exported video files.

Yes, audio files can be exported into WAV audio files. Note that these files may not be playable on Windows Media Player. Use a robust media player (i.e. VLC) for playing back exported audio files.

Audio Recording

5. Developer Tools

There are three OptiTrack development APIs that are useful for developing a custom application: the Camera SDK, the NatNet SDK, and the Motive API. All of the APIs support a C/C++ interface.

The

Camera SDK

provides access to the most fundamental data, such as grayscale images and 2D object information, from each camera. In addition, the Motive API also allows control of and access to the backend software platform of Motive. Not only does it allow access to 2D camera images and the object data, but it also gives control over the 3D data processing pipeline.

The

NatNet SDK

is a client/server networking SDK designed for sending and receiving motion capture data across networks. The NatNet SDK makes the motion capture data available to other applications 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.

Motive API: Quick Start Guide

Camera SDK

NatNet SDK

Camera SDK

is free software available for download from the OptiTrack website.

Motive provides advanced 3D and 6DoF tracking capabilities and may be purchased separately.

Yes, the Camera SDK supports multi-camera synchronization with all OptiTrack cameras. In fact, all OptiTrack cameras are synchronized at the hardware level. But note that using synchronized cameras to reconstruct markers into a 3D space cannot be done through the Camera SDK.

We request that OptiTrack runtime components be delivered using the installers we provide; they should not be repackaged. This helps ensure that everything is installed properly and also allows the user to read through the license which accompanies them. Most installer engines have the ability to invoke another installer during the installation process.

If you have a special distribution request, please

to discuss it in detail.

The preferred approach is to link to the Camera SDK installer hosted on the NaturalPoint web servers. However, if you would like to bundle our installer with your application, a formal endorsement is necessary.

In order to get a formal endorsement, please contact

support@naturalpoint.com

and provide contact information and detailed information about your project.

1. General

With our Primex 41 series setup, usable capture volumes up to 75’ x 150’ (11,250 square feet) are supported.

Prepare Setup Area

The maximum distance from the host PC to the camera depends primarily on cable length limitations. Every cabling type has its allowable cable length, and attempting to cable at a longer distance will result in degraded data transmission.

For USB: The maximum USB cable length for a direct connection is 5 meters (16 feet). Hubs and active extension cables can be used to increase the usable distance. The recommended configuration for large volumes is to connect hub(s) to the computer using active extension cables, then connect cameras directly to the hub(s) with no extensions in between.

For Ethernet: Ethernet PoE cables can transfer data and power up to 100 meters (328 feet). In other words, the maximum length of 100 meters is allowed for both the cabling from an Ethernet camera to an Ethernet switch and the cabling from an uplink switch, or a host PC, to an Ethernet switch. Multiple Ethernet switches/repeaters may be used.

Cameras should be setup so that they do not shake and are not easily moved. If any camera is moved once calibrated, tracking accuracy will be affected and the cameras should be re-calibrated. Suitable mounting hardware includes tripods on concrete floors, truss work, and wall mount brackets.

The cameras are compatible with both active and passive markers. Active markers work best when using LEDs that produce output in the 850 nm wavelength.

Active Marker Tracking

Ethernet and USB cameras cannot be used together on one system.

All OptiTrack Ethernet cameras can be used together in the same system. All USB cameras can be used in the same system except for the Flex 13, which uses a different timing mechanism.

Yes, 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 less trackable range of motion when compared to tracking fully spherical markers.

A variety of retro-reflective passive markers that are optimized for motion capture are available for purchase on our

webstore

For USB cameras:

Using a 5m USB cable from an OptiTrack camera may result in a “Device not recognized “ or “unknown device” error on some computer systems due to USB limitations. Using a shorter USB cable often resolves the issue. When plugging 5m USB cables directly into a computer, avoiding ports on the front of the tower will reduce the likelihood of cable-related errors.

Flex 13 cameras will not work when directly connected to the PC. Flex 13 cameras require more power, and they need to be routed through the OptiHub 2.

For Ethernet cameras:

Ethernet cameras will not work when directly connect to the PC because standard PC Ethernet ports do not supply power to the cameras. Instead, Ethernet cameras must be routed through PoE switches to deliver sufficient power over the Ethernet for each camera to operate.

All OptiTrack cameras are synchronized at the hardware level of the system.

For V120:Duo/Trio, all cameras are synchronized within the device itself.

For Flex series, all cameras are synchronized through communicating the sync information over the USB cable and the OptiHub2, without requiring separate RCA synchronization cables.

Primex series cameras are synchronized by communicating the time information with each other through the camera network itself using a high-precision algorithm for timing synchronization.

Synchronization

All OptiTrack cameras (other than the V120:Duo and V120:Trio tracking bars) can be re-focused to optimize image clarity at any distance within the camera’s tracking range. By default, OptiTrack cameras are focused at infinity, which means that they are tuned to track from distances as near as a few feet away up to their maximum tracking range. For very close-up configurations (e.g. tracking markers from 1-4’ away from cameras), tracking quality can be improved by refocusing for clarity at that range.

Aiming and Focusing

OptiTrack cameras, except for Slimx and Prime Color series, already have a built-in IR LED ring around the camera lens to be used as a lighting source, and the illumination setting can be adjusted easily through the software. The LED ring usually provides enough illumination for each camera in various applications. However, when configured correctly, it is possible to use an external illumination source to provide extra lighting for detecting passive markers.

2. Ethernet Camera System

Only Ethernet OptiTrack camera models are compatible with the eSync2, which includes Primex series, S250e*, and Slimx 13. The eSync2 allows synchronization of the motion capture system to almost any signal or source. Only one eSync2 is necessary per system.

External Device Sync Guide: eSync2

OptiTrack Ethernet cameras require PoE (Primex 13, Primex 13W, Slimx 13) or PoE+ (Prime x 41, Primex 22, Prime Color) Gigabit (1000 Mbit/s) Ethernet switches.

Standard PoE switches must provide a full 15.4 watts to every port simultaneously, and PoE+ switches must provide a full 30 watts to every port simultaneously. Even though Primex 22 and Primex 41 cameras can still operate with the PoE switch, the PoE+ switch is required to operate the LED array at its maximum performance. Furthermore, the switch must support Gigabit transmission, 1000 Mb/s, for every Ethernet port on the switch in order to accommodate for high data traffic.

Quick Start Guide: Getting Started

Cabling and Wiring

All Prime series cameras come with a status indicator ring. It provides information about the current camera state.

Camera Status Indicators

3. USB Camera System

Yes, this is possible. But note that the OptiHub* will attempt to synchronize the cameras at 100 Hz frame rate by default. For connecting Slim 3U cameras, check and set the frame rate to 120 Hz in the Custom Synchronization Settings found under the Tools tab in Motive.

Slim 3U, V100:R1* and Flex 3 cameras can be used in the same Wired Sync chain. Flex 13 cameras support an alternative synchronization method and they cannot be incorporated in the Wired Sync chain.

In place of the Wired Sync method, the OptiTrack USB cameras (except for Slim 3U) utilize a custom synchronization protocol called OptiSync. It allows USB cameras to communicate sync signals through a single USB cable without requiring separate sync cables.

External Device Sync Guide: OptiHub2

When operating in External Sync mode, a valid external trigger is required for cameras to work.

The OptiHub*’s blue LED indicates the external trigger status. If the blue LED is not blinking, the OptiHub* is not receiving a valid external trigger signal, and the cameras will be stalled. This is the intended behavior, so it is important to check whether the external trigger signal is functioning properly.

If necessary, investigate further by putting a scope to the External Sync-Out jack when the problem occurs. If you are using a video adapter sync out as your source, you should see a 50% square-wave at half the frequency of your video adapter's screen refresh rate.

Also note that the blue Sync LED indicates whether trigger events are happening, but not necessarily the presence of an external sync input. The OptiHub* will free-run in the absence of an External Sync-In signal. In this case, the blue LED will illuminate even though an external sync input is not connected, because a valid trigger event is still detected.

V120:SLIM (9-pin header) pin-out settings:

GND1
IRLED_CTRL_OUT2
AUX_OUT3
GND
GND
VCAP_OUT4
3.3V5
EXT_SYNC_IN6
EXT_SYNC_OUT7

For more information, view the

V120:SLIM technical drawings

, which identify the Micro-T pin locations.

SLIM:V100 (8-pin header) pin-out settings:

GND8
5V
3.3V
I2C SCL
I2C SDA
LED OUT
SYNC OUT
SYNC IN

Be careful to draw no more than 50ma from the 3.3V supply.

The available IR LED modes on Flex series cameras are determined by the hub type they are connected to. The OptiHub* is a legacy device that has been replaced with the OptiHub 2. Both are designed to provide power and synchronization options for the USB system, but the OptiHub 2 is designed to provide more power to operate the LED array.

Flex 13

OptiHub*: no LED illumination enabled
OptiHub 2: high-power LED illumination mode

Flex 3 (V100:R2)

Generic USB Hub: Standard LED illumination mode
OptiHub*: Standard & high-power LED illumination mode
OptiHub 2: Standard & high-power LED illumination mode

Flex 13 cameras can still transmit the data when connected to an OptiHub*; however, LED illumination will be disabled due to insufficient power. They must be connected to the OptiHub 2 to power the on-camera LED illumination.

The OptiHub* can be incorporated in the same system with the OptiHub 2. Due to higher power requirements, when Flex 13 cameras are present, they must all be routed through an OptiHub 2.

The customer purchases a software product for which a license is required.
The customer will receive an activation code and a serial number.
The customer will then activate the license using the provided codes and the serial number from the Hardware or Security key.
The activation process will provide the customer with a license file that allows the software to be used as long as the matching camera or hardware key (serial number) is present.
The customer can download new versions of the software as long as their license is valid.
If the license is time limited, updates must be purchased to extend the period for which it is valid. The version of the software for which the customer's license was originally valid will continue to work even if the license expires.

Software licenses must be locked to a USB Hardware or Security Key for most system types, depending on your version of Motive. Moving either USB Key to another computer also requires the user to transfer the associated software license file to the new machine. This allows software licenses to be moved between different locations more easily, without disturbing cameras in a calibrated setup.

The USB Keys do not contain a license themselves. Software licenses must be purchased separately and locked to the Hardware or Security Key. This results in downloadable license files which must be used along with the key.

The Security Key must register with the connected cameras upon initial activation, or when one or more cameras are added to an existing system. This process requires that the host PC be connected to the internet and may take a few minutes. Once the cameras have been registered, an internet connection is no longer required.

We provide two methods for our customers to activate a new license:

The first method is to use the
License Activation Tool
that is included with Motive. This tool can be found on the Motive splash screen after launching Motive. Click the License Tool button to launch the Activation Tool.
The second method is to use our
Online License Tool from the
Support webpage
. This method will send an email with the license file attached. Note that you may need to check your spam folder. Download the license file to C:\ProgramData\OptiTrack\License.

To activate the software you will need your License Serial Number, License Hash, and Hardware Key Serial Number. The License Serial Number and License Hash can be found on the software activation card and on the order invoice, and the Hardware Serial Number can be found on the Hardware or Security Key. Note that if you ordered a software license and chose email delivery, you will not receive a software activation card.

License Activation Tool Window

Online License Tool from Support webpage

OptiTrack software can be used on a new computer by reactivating the license, using the same license information. After the license has been reactivated, the corresponding USB Hardware or Security 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 Start Menu -> All Programs -> OptiTrack -> Motive -> OptiTrack License Folder.

The term of your software license is as provided in the end user licensing agreement (EULA) provided with the software, or if no EULA is included, the EULA is as provided at

here

. Most OptiTrack software licenses are perpetual and do not expire.

After a set period of time elapses after activation (usually a year), you will no longer have access to updates or new releases of the software unless you elect to purchase a software maintenance plan. You will continue to have access to versions of the software that were released during the activation period.

By purchasing OptiTrack software you will have access to software updates and bug fixes for a set period of time (usually a year) starting from the initial activation date. However, Customers may purchase a software maintenance plan to gain access to updates and bug fixes for the version of software purchased.

If a customer allows a software license to lapse, they must purchase updates to cover the entire lapsed time period in order to bring their plan into a current valid state (or purchase a new license). Please check the status of the plan through the Check My License tool on our website.

You can still use Motive with an expired maintenance plan as long as you have a valid Motive license for your version of Motive. However, you will no longer receive updates or bug fixes.

NaturalPoint reserves the right to cease providing updates and bug fixes to software it designates as EoL. A software maintenance plan is not a warranty. Software is provided AS IS, without any express or implied warranties, and all purchases are subject to the NaturalPoint Terms & Conditions of Sale.

For customers still using Arena and Tracking tools: These licenses are no longer supported, and it is recommended to upgrade to Motive. Please contact a Sales Engineer to purchase a Motive license.

Installation and Activation

The license may be extended up to two years into the future. NaturalPoint reserves the right to cease providing updates and bug fixes to software it designates as EoL.

The Camera SDK does not require a license. You can also download the SDK from our website to review it before purchasing.

A new hardware key will need to be purchased and registered to the existing software license. Before purchasing the new Hardware or Security Key, please contact

Support

for assistance.

Transferring the software license to a different USB Hardware or Security Key is possible but only through contacting

Support

for assistance.

No, purchasing a license is not required when using a V120:Duo/Trio, as the device itself acts as a USB Hardware Key and also includes a built-in, perpetual Motive:Tracker license.

The status of a previously activated software license can be found through the

Check My License

tool on our website. The status will be displayed if you input the Device Serial Number and License Hash Code in the license tool.

FAQs

General FAQs

System Setup FAQs

Licensing & Activation FAQs

FAQs

General FAQs

System Setup FAQs

Licensing & Activation FAQs

3. Camera Settings

4. Motive and Data Streaming

5. Developer Tools

1. General

2. Ethernet Camera System

3. USB Camera System