How eye tracking works and why it matters

For more than two decades, Tobii has advanced the field of eye tracking, helping researchers and innovators understand how people look, think, and navigate the world. But before exploring what eye tracking can unlock, it’s helpful to understand how eye tracking technology actually works. From detecting subtle eye movements to interpreting gaze patterns in real time, here’s a clear look at the core mechanisms that make modern eye tracking possible.

What is eye tracking? 

Eye tracking is a sensor technology that detects and records the position and movement of the eyes. It determines where a person is looking, called the point of gaze. This technology can be applied to computer screens, in real-world environments, or within virtual reality settings. Eye trackers may operate as standalone devices or be integrated into other systems such as XR headsets, computers, and vehicles.

How does eye tracking work?

1. Illumination of the eyes: Tobii eye trackers use near-infrared light to illuminate the eyes, creating light reflection patterns on the pupil and cornea. This method, known as pupil-center corneal reflection (PCCR), helps estimate the point of gaze. 

2. Reflection detection by sensors: Camera sensors capture images of the eyes and reflections. Depending on the eye tracker speed, you can acquire detailed information about specific eye movements. For instance, Tobii Pro Spectrum captures images every 0.833 ms (1200Hz), allowing the tracking of microsaccades. 

3. Image processing and analysis: Advanced algorithms are employed to estimate a 3D model of the eye and determine its spatial position. The pupil center and corneal reflection are detected to facilitate precise calculation of the gaze point. 

Why use near-infrared light? 

Near-infrared light is invisible to the human eye, ensuring no discomfort or distraction. It provides stable illumination in various conditions, ensuring reliable and accurate eye tracking results. 

Screen-based eye trackers: Mounted on a desktop or laptop screen, these
eye trackers calculate the eye’s position and gaze point on the monitor. They are widely used in scientific research, gaming, and consumer research. 

Wearable eye trackers: Wearables are worn like regular glasses and have a front-facing camera that records what the user is looking at. They offer firsthand insights into real-world environments and are utilized in research, training, and assessment. 

Eye tracking in XR headsets: In XR headsets, eye tracking components include cameras and light sources. Machine-learning algorithms interpret the camera feed to generate real-time data points, such as pupil size and gaze vector, thereby enhancing user experience in healthcare, training, simulation, and other applications. 

Unlocking deeper understanding of behavior

Tobii's eye tracking technology offers a powerful tool for understanding human behavior and enhancing various applications. Whether it's enhancing virtual reality experiences, improving road safety, or advancing scientific research, eye tracking provides valuable insights.