Northern Digital

Northern Digital Inc.
Information
Industry	Optical and electromagnetic tracking, medical device components
Founded	1981
Founder	Jerry Krist
Headquarters	Waterloo, Ontario, Canada
Notable Personnel	David Rath (named president in 2012)
Products	Optotrak, Polaris, Aurora, 3D Guidance, Atraxa
Parent	Roper Technologies (from 2011)
Website	https://www.ndigital.com

Northern Digital Inc. (NDI) is a Canadian maker of optical and electromagnetic 3D tracking systems, based in Waterloo, Ontario. Its current products, the Polaris optical trackers and the Aurora and 3D Guidance electromagnetic tracking systems, are designed as components that medical device manufacturers build into image-guided, navigation and positioning systems. Its earlier Optotrak optical tracking platform was introduced in 1990. The company was founded in 1981 by Jerry Krist and has been a subsidiary of Roper Technologies (then Roper Industries) since June 2011. In 2012 Roper bought the Vermont tracker maker Ascension Technology, which became a division of NDI.

NDI's main link to virtual reality and augmented reality hardware is Atraxa, an electromagnetic and inertial tracking reference design for VR headsets and controllers that the company showed at CES 2019. Atraxa was used for the controllers of the Pico Neo 2 standalone headsets and was listed as an embedded technology partner in Qualcomm's Snapdragon XR2 reference design.

Reviewed 21 October 2026. Founding, product timeline, ownership (Audax 2007, Roper 2011, Roper 2025 10-K), Ascension purchase, Polaris and Aurora specifications, Atraxa CES 2019 hands-on, Pico Neo 2 and Snapdragon XR2 reference design, WorldViz tutorial and STTAR paper checked against the cited NDI pages, SEC filings, archived NDI pages and press articles. About review dates.

History

Founding and optical tracking

NDI says it began in 1981 in a basement, with a small team of University of Waterloo graduates working on precision instruments for industrial measurement. A Waterloo Economic Development Corporation profile, last updated in June 2023, describes the founder, Jerry Krist, as a former professor of computer science at the University of Waterloo.

In 1984, working with the university's Department of Kinesiology, NDI released WATSMART, its first optical motion tracking system. An archived NDI timeline says WATSMART was used mainly in biomechanics research and was discontinued in 1990, when the Optotrak replaced it. Optotrak tracked small infrared markers attached to a subject and gave 3D and six-degree-of-freedom measurements in real time.

The same 1990s timeline records a ruggedized Optotrak RH-2020 for wind tunnels (1992), a customized Optotrak for Johnson & Johnson's ACUSTAR I image-guided neurosurgery system (1994), and the first Polaris optical tracking systems (1996), with passive and hybrid Polaris versions following in 1997. NDI also stated that Optotrak was used to capture human expression and movement for the 1998 film Godzilla. In 1999 the company moved to Randall Drive in Waterloo and signed a cooperative agreement with Mednetix AG of Switzerland to develop a magnetic measurement system together.

Electromagnetic tracking and expansion

NDI opened a European office in Radolfzell, Germany, in 2001 and acquired Mednetix AG in 2002. It opened an Asia Pacific sales office in Hong Kong the same year. Aurora, its first electromagnetic tracking system, came out of the joint work with Mednetix and was announced in 2003. NDI announced the Optotrak Certus in 2004 and launched the Polaris Vicra and Polaris Spectra optical trackers in 2005-2006.

Ownership changes

On 21 December 2007 NDI announced that it had sold a controlling interest to the private equity firm Audax Group. At the time the company was headquartered in Waterloo with offices in Germany and Hong Kong, and it described its applications as ranging from image-guided surgery to biomechanics, human motion capture and portable metrology. In April 2008 Jamie A. Fraser, previously of Amphenol, succeeded David G. Crouch as president and CEO.

Roper Industries bought all of NDI's shares on 3 June 2011 for 200 million Canadian dollars (205 million US dollars). Roper added NDI to its medical platform and reported it in its Medical and Scientific Imaging segment. In June 2012 David Rath, who had joined NDI in 2004 and led its Medical Division from 2007, was named president, succeeding Fraser.

Roper also bought Ascension Technology, a Vermont maker of magnetic trackers, in 2012. NDI announced the deal in late July 2012 without disclosing terms, and Ascension became a division of NDI that kept making its magnetic sensors in Vermont. NDI's history says the purchase strengthened its electromagnetic tracking range and gave it a site in Shelburne, Vermont.

In Roper Technologies' annual report for 2025, Northern Digital is one of eight businesses in the Technology Enabled Products segment, described as supplying "optical and electromagnetic precision measurement systems for medical and industrial applications." The Waterloo EDC profile put NDI's staff at 120 employees in Waterloo and about 100 elsewhere, and quoted Rath as president. As of October 2026 NDI lists offices in Waterloo (head office), Radolfzell, Shelburne and Hong Kong, and says it has more than 45,000 installations worldwide and holds over 100 patents.

Products

Product	Type	Introduced	Notes
WATSMART	Optical motion tracking	1984	Developed with the University of Waterloo's Department of Kinesiology; discontinued in 1990
Optotrak	Optical measurement	1990	Tracks infrared markers for real-time 3D and 6DOF measurement; Optotrak Certus announced 2004
Polaris	Optical tracking	1996	Current models Polaris Vega ST, VT and XT and Polaris Lyra
Aurora	Electromagnetic tracking	2003	Jointly developed with Mednetix AG
3D Guidance	Electromagnetic tracking	Added with Ascension (2012)	trakSTAR desktop and driveBAY embedded electronics units
Atraxa	Electromagnetic and inertial tracking reference design for XR	Shown at CES 2019	Intended for OEMs, not sold to consumers

Polaris

Polaris is NDI's line of optical trackers for surgical navigation. NDI says it was built for integration into the navigation systems of other manufacturers, used in neurosurgical, spine and orthopaedic procedures. The Polaris Vega launched in 2016 with integrated video capability and radiation hardening. It was followed in 2019 and 2020 by the Vega ST, the Vega VT with video, and the Vega XT, and in 2023 by the compact Polaris Lyra, which replaced the Polaris Vicra. The trackers work with retro-reflective passive marker spheres or with active markers that emit near-infrared light.

NDI's published specifications for the current models are:

Model	Intended use (per NDI)	Accuracy (RMS)	Max frame rate	Latency
Polaris Vega ST	Radiation suites	0.12-0.15 mm	60 Hz	<17 ms
Polaris Vega VT	AR and video-enabled visualization	0.12-0.15 mm	60 Hz	<17 ms
Polaris Vega XT	Robotics and high-speed navigation	0.12-0.15 mm	400 Hz	<3 ms
Polaris Lyra	Compact operating room setups	0.20-0.25 mm	125 Hz	<5 ms

NDI describes the Vega VT as combining optical tracking with integrated HD video "to support Augmented Reality (AR) and machine vision workflows within OEM surgical navigation systems."

Aurora

Aurora is NDI's electromagnetic tracking system for locating sensors inside medical instruments such as needles, catheters, ultrasound probes and laparoscopes, where line of sight to an optical tracker is limited. A system has three parts. A field generator emits a low-intensity electromagnetic field; a Sensor Interface Unit amplifies and digitizes the sensor signals; and a System Control Unit drives the field generator, calculates each sensor's position and orientation, and talks to the host computer.

As of October 2026 NDI offers six field generators (Planar 10-11, Planar 10-11 H, Planar 20-20 V2, Planar 20-20 X2, Window 50-60 and Tabletop 50-70) and more than 20 standard sensors for five- and six-degree-of-freedom tracking. The smallest sensor, 0.3 mm by 2.5 mm, was completed in 2021, and the Planar 20-20 X2 field generator, a thinner and lighter version of the Planar 20-20, launched in 2025. The Planar 20-20 X2 covers a 50 by 50 by 50 cm cube and a dome with a 66.0 cm radius, according to NDI.

3D Guidance

The 3D Guidance electromagnetic line came to NDI with Ascension Technology. NDI sells it with the desktop trakSTAR or the embedded driveBAY electronics unit, mid-range and short-range transmitters, and pre-wired six-degree-of-freedom sensors. NDI says the short-range transmitter can be mounted inside surgical simulation phantoms.

XR work

Atraxa

Atraxa is a reference design for magnetic tracking of VR headsets and controllers, aimed at device makers rather than consumers. Road to VR tried it at NDI's booth at CES 2019. NDI offered it as an enclosed controller or as three bare circuit boards: two trackers and one receiver. Each tracker module combines an IMU with a transmitter coil that generates an electromagnetic signal. The receiver, ideally built into the headset, measures the transmitters' fields and handles wireless communication with the trackers, and an optional computer module calculates poses for the host application. The headset's own tracking supplies the receiver's position; a headset without tracking can use a static base station for both head and hands.

In the demonstration NDI mounted its receiver on a Samsung Odyssey headset running SteamVR, with Beat Saber and The Lab. Road to VR's Scott Hayden wrote that the controllers kept 6DOF tracking behind the back, behind the head and at his sides, positions that often defeat optical inside-out tracking. He also saw the controllers drift a few centimetres and snap back twice, and judged accuracy and latency to be around the level of PlayStation Move and below other major PC VR controllers. An NDI spokesperson told him that Atraxa was already integrated into one or more XR headsets on the market but would not say which.

The Pico Neo 2 and Neo 2 Eye, whose price and availability Pico announced in May 2020, used controllers tracked with NDI's Atraxa platform, fusing data from an on-board electromagnet and an IMU instead of tracking them optically. In February 2020 Qualcomm's announcement of the Snapdragon XR2 5G reference design, a VR form factor developed by Goertek, named Atraxa as an embedded technology partner for 6DoF controller and peripheral tracking without line-of-sight restrictions, alongside compatibility with embedded eye tracking from Tobii.

Research and simulation

NDI's optical systems have also been used in VR and AR research. In 2009 WorldViz published a tutorial for streaming position and orientation data from an Optotrak into its Vizard VR software and linking a 6DOF sensor to the viewpoint. In surgical AR work, a 2022 paper by Alejandro Martin-Gomez and colleagues named NDI's Polaris as an example of the medical-grade infrared trackers whose retro-reflective markers can also be seen by the built-in cameras of AR headsets, and presented a framework that tracks such markers with the built-in cameras of a Microsoft HoloLens 2, without adding tracking hardware. The Waterloo EDC profile lists virtual reality simulation among the applications of NDI's tracking technology, next to image-guided surgery, biomechanics research and automotive assembly.

See also

• Ascension Technology
• Polhemus
• Electromagnetic tracking
• Optical tracking