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What Is Eye Tracking? A Basic Definition

(Image credit: MaximP/Shutterstock)

How does eye tracking work? And what does 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 the almost-infrared light, so this 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)

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, which, compared to the predecessor added simultaneous eye and head tracking, lowered power consumption and CPU load reduction, changed data transfer from 2 GBps to 100 KBps and added USB 3.0-to-USB 2.0 connectivity. At the time of writing, there are currently 146 games that support Tobii eye tracking.

To enjoy Tobii eye tracking in your game of choice, you have a few options. Your first is buying Tobii’s eye tracking module, called Tobii Eye Tracker 4C, to attach to your gaming laptop or monitor via the included USB 2.0 cable. The tracker has an MSRP of $169 / €169, and Tobii bundles it with a free PC game, but you can sometimes find it on Amazon without a game for less.

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

For desktop gamers, 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 are 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. You can also get the same effect with a webcam with an IR camera, like the Logitech 4K Pro (Microsoft’s recommendation) or LitBit Face Recognition Camera.

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 VR headsets. The former is primarily in development or targeting business use. This year, the HTC Vive Pro Eye VR headset, also for businesses, came out with built-in Tobii eye tracking. And in July, Tobbi announced Tobii Spotlight Technology, which uses eye tracking to improve dynamic foveated rendering in VR headsets for a smoother overall experience. It's already being used in the Pro Eye but has 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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