Optotrak Certus

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The Optotrak Certus® motion-tracking system offers unrivalled temporal accuracy and resolution for real-time kinematics research. System features such as pre-calibration, automatic marker identification, and minimal lag time put the focus on flexible and reliable 3D motion capture. This is why Certus is trusted by thousands of researchers—and cited in thousands of published papers—around the world.

Certus uses lightweight markers that are attached to the subjects’ hands, face, joints, etc. Certus measures the markers’ coordinates using active optical tracking technology. Position measurements are recorded as discrete 3D data points (not 2D images). Position data is calculated after the position measurement is taken.

Optotrak Certus optical tracker research grade motion capture position sensor

Research Grade
Northern Digital Inc. specializes in designing and manufacturing research-grade motion capture systems as opposed to animation-grade motion capture systems. While some less accurate motion capture systems must sample data at higher rates and then average that data to increase the measurement accuracy, Certus captures each data point with micron-level accuracy and precision, independent of the sampling rate.

High Accuracy and Reliability
Certus provides exceptional spatial and temporal accuracy. With an accuracy of up to 0.1 mm and a resolution of 0.01 mm, you can be sure that Certus data are objective and accurate. The exceptionally accurate kinematic data recorded by Certus minimizes RMS error when reconstructing a continuous position trajectory, even if it contains sudden or imperceptible position changes.

True Real-Time Data
Certus delivers true real-time data 100% of the time. The exceptionally low latency of this data makes it ideal for virtual reality and other feedback applications.

Full Control of Data
With Certus, you have full access to how the measurement data is manipulated, analyzed, and presented. This is especially important when deriving velocity and acceleration profiles, where any inaccuracies in the data will magnify errors in the position signal. Such errors could negatively affect the reliability and outcome of your experiment. Certus provides noiseless, high-quality data that you can trust every time.

No Data Sorting
Spend time doing research instead of sorting data! Each marker is automatically and individually tracked. Certus will never misidentify markers or lose their identities. This means that time-consuming and error-prone manual data sorting is never required. As soon as you have collected data from your subject, you are ready to start analyzing.

Certus can track up to 512 markers and has a maximum marker frequency of 4600 Hz, allowing you to capture data at high speeds.

No Reflections
Certus is not hampered by false signals created by reflections; thus, there is no need for any special preparations for your lab.

Easy to Use
The pre-calibrated system allows for out-of-the-box use. Certus is available with a range of intelligent strobers, allowing you to configure the marker activation order through provided software.

White Papers

Research Articles

  • Evers, J. Lakemeier, M., Wähnert, D., et al. “3D Optical Investigation of 2 Nail Systems Used in Tibiotalocalcaneal Arthrodesis: A Biomechanical Study.” Foot & Ankle International, vol. 38, no. 5, 2017, pp. 571–579.
  • Hangalur, G. Brenneman, E., Nicholls, M., et al. “Can a Knee Brace Reduce the Strain in the Anterior Cruciate Ligament? A Study Using Combined in Vivo/in Vitro Method.” Prosthetics and Orthotics International, vol. 40, no. 3, June 2016, pp. 394–399.
  • Riddell, Maureen F. Gallagher, Kaitlin M., McKinnon, Colin D., Callaghan, et al. “Influence of Input Device, Work Surface Angle, and Task on Spine Kinematics.” Work, vol. 55, no. 4, 1 Jan. 2016, pp. 773–782.

Technical Specifications

3D Accuracy up to 0.1 mm
Maximum Frame Frequency 4600 Hz / (number of markers + 1.3)
Marker Frequency 4600 Hz
Resolution 0.01 mm

Marker Types Active
Max. Number of Markers 512
Data Communication
Communication Ethernet, USB

Optotrak Certus Measurement Volume


The Certus system comes with NDI First Principles™ software for collecting, managing, and presenting 3D and 6DOF measurement data in real-time or through post hoc analysis.

The NDI Optotrak software package includes the following programs:

  • NDI First Principles provides an easy way to observe, record, playback, and manage data produced by Certus. First Principles also allows for easy integration of third-party devices such as force platforms, EMG systems, and eye trackers.
  • DataView allows the viewing of Optotrak motion capture data files by frame or marker as a graph or text.
  • 6D Architect simplifies the tool characterization process as well as the creation of tool definition files.

Optional Software

The following are also compatible with the Certus motion capture system:

  • Optotrak Application Programmer’s Interface (OAPI) by NDI
  • Visual3D™ by C-Motion
  • Vizard™ by WorldViz
  • Motion Builder®by AutoDesk®
  • Caren platform products by Motek
  • MatLab®
  • LabView™ using OAPI



System Arrangements by Measurement Volume

Based on your specific tracking application learn more about what system arrangement is most suitable.

Small Volume

Optotrak Certus Reaching GraspingMeasure fast, imperceptible movements with exceptional temporal accuracy and resolution using just one Certus optical tracker.

Small-volume tracking applications such as tremor pathology, muscle onset delay, and in-vitro tissue mechanics require 3D motion tracking with exceptionally high temporal accuracy and resolution. Certus provides neuroscientists and orthopaedics researchers with 3D measurement and motion tracking of small-amplitude movements in real-time.

Just one Certus optical tracker covers a tracking volume up to 20 m3, and the factory pre-calibration that Certus offers allows for quick system setup. Certus has a sampling rate of up to 2000 Hz, which ensures that the most subtle and fastest of movements are captured.

Medium Volume

Optotrak Certus Force Plate Biomechanics

Track localized kinematic movement in real-time from multiple angles using two or more Certus optical trackers.

Medium-volume motion tracking applications such as reaching and grasping, posture and balance, and prosthetics research require localized measurement of fine movements. Data must be accurate and reliable, and it must be captured without any gaps in the measurement volume.

Using two or more Certus optical trackers, researchers can set up a large pre-calibrated tracking volume that provides complete measurement coverage from multiple angles. Certus uses active optical tracking technology to capture kinematic data with exceptional accuracy and precision.

Large Volume

Optotrak Certus BiomechanicsCapture full-body motion within a large pre-calibrated tracking volume using three or more Certus optical trackers.

Large-volume motion tracking applications such as gait analysis and sports medicine require accurate and reliable capture of full-body motion, through all the planes and axes of human movement. Whether your experiment is comparing different subjects or assessing how movement changes within one subject, the measurement system must be able to track each motion without interfering with the subject’s natural movement.

Certus provides biomechanics and sports medicine researchers with real-time 3D tracking data to study gait patterns and movement pathologies and to research and develop prosthetics and injury rehabilitation/treatment. Multiple factory pre-calibrated position sensors can be registered together to create a very large measurement volume. This allows for the tracking of kinematic movement from multiple angles. When using the Optotrak Data Acquisition Unit, signals from third-party sources such as force plates and EMG sensors can also be synchronized within the data set, even during long data collection processes.


Optotrak Accessories

Optotrak Accessories

Customize your Optotrak motion capture system with a wide range of markers, tools, strobers and stands that enhance setup flexibility and ease of use.

Optotrak Accessories

Legal Disclaimer
NDI tracking and measurement products (listed below) are general metrology components that can be integrated into customer products, research experiments, and/or as components of medical devices that require precision measurement and tracking. While NDI components and technology can be integrated into original equipment manufacturer (OEM) medical devices, they are not specifically intended for a given application and, as such, have not been developed or manufactured in accordance with medical device standards.  It remains the responsibility of the OEM customer or end-user to determine and test the suitability of NDI components and technology for their intended use, including performing any required ethics approval, verification, and validation required to demonstrate suitability and compliance. System-level testing, certification, and validation are the responsibility of the original equipment manufacturer or the applicable end-user and should be completed prior to use of NDI products or technologies in any application.