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What Is Eye Tracking? A Basic Definition

What is eye tracking exactly?  (Image credit: MaximP/Shutterstock)

How does eye tracking work? And what does the popular eye tracking technology Tobii mean for common consumer uses, like gaming and Windows Hello?

Eye tracking technology follows a user’s point of gaze by keeping a record of the eyes’ positioning and movement. According to biometrics hardware and software vendor iMotions, eye tracking is done “in relation to the environment and is typically based on the optical tracking of corneal reflections, known as pupil center corneal reflection (PCCR).”

How does eye tracking work?

Eye tracking works by pointing a light (not infrared, but almost) at the pupil. This creates reflections at the cornea. An infrared (IR) camera tracks these reflections, thus tracking the movement of your point of gaze. The technology can tell the difference between your pupil and iris, since light will enter the pupil but bounce off the iris. Note that humans can not typically / easily see this almost-infrared light, so it isn’t a distraction to users.

For more information on how eye tracking works, check out the following infographic, shared courtesy of iMotions neuroscientist and lead product specialist Dr. Elvira Fischer.

(Image credit: Dr. Elvira Fischer/iMotions)

What is Tobii eye tracking for gaming?

Tobii eye tracking is currently the most popular form of consumer eye tracking and particularly exciting for tech enthusiasts because it brings eye tracking to gaming. 

Here’s how Tobii eye tracking works, in the company’s own words:

(Image credit: Tobii)

At the time of writing, there are currently 153 games that support Tobii eye tracking.

Tobii eye tracking offers various gaming features, which differ from title to title. The technology can provide Natural Targeting, like being able to select something, fire a weapon or aim with a look, Gaze Awareness, where the game’s display reacts based on what you’re looking at, and Infinite Screen, for extended views and quick head tracking in simulator games.

The current version of Tobii’s tech uses a second generation Tobii EyeChip. Compared to its predecessor, the Tobii EyeChip adds simultaneous eye and head tracking, lower power consumption and CPU load reduction. It also changed data transfer from 2 GBps to 100 KBps and added USB 3.0-to-USB 2.0 connectivity.

If you want to be able to use the eye tracking features in any of the 153 games that support Tobii's technology, you have a couple options. Your first is buying Tobii’s eye tracking module. Today, Tobii replaced its Eye Tracker 4C with the Tobii Eye Tracker 5. You can attach the Eye Tracker 5 to your gaming laptop or monitor via the included USB 2.0 cable. The tracker has an MSRP of $229

Alternatively, you can buy a gaming laptop with Tobii eye tracking built in. At the time of writing there are seven:

The Acer Predator XB271HUT gaming monitor was made with baked-in Tobii eye tracking, but it’s hard to find new.

Eye tracking and Windows Hello

With the Tobii eye tracker, you can also use Microsoft’s Windows Hello feature to log into a PC with your face. There is a small number of laptops with Windows Hello cameras built-in, but you can give any Windows PC this functionality but attaching a Tobii eye tracker, like the aforementioned Eye Tracker 5. 

You can also get the same effect with a webcam with an IR camera, like the Logitech 4K Pro

With the proper Tobii software, you can also control different Windows Interaction features. These include the ability to have your monitor’s brightness automatically dim when you’re not looking or turn on when it sees your eyes, control your mouse, select apps and more.

What else uses eye tracking?

A number of enterprises have been using eye tracking technology to get work done since way before it entered the consumer space. There is more heavy-duty eye tracking hardware available for these use cases, including for relevant content developers.

Naturally, eye tracking is being considered for use in various head-mounted displays (HMDs), like AR smart glasses and offerings looking to be the best VR headset for certain business-focused tasks and training. The former is primarily in development or targeting business use, while we've already seen the first VR examples in the HTC Vive Pro Eye and Pico Neo 2 Eye.  Today, HP announced the upcoming HP Reverb G2 Omnicept Edition HMD, which will feature the Tobii EyeChip eye-tracking ASIC, along with other biometric sensors. 

Last summer saw the debut of Tobii Spotlight Technology, which uses eye tracking to improve dynamic foveated rendering in VR headsets for a smoother overall experience. The Pro Eye and Neo 2 Eye already use the feature, and there's hope for consumer uses too. 

Oculus, Facebook’s VR company, has also told us that they’re exploring introducing eye tracking into its headsets and has shown off a prototype and secured a patent, so there's another piece of hope for consumer VR eye tracking.

This article is part of the Tom's Hardware Glossary.

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