All of the world’s top virtual reality headset makers agree that gaze tracking is going to be fundamental to the next generation of VR hardware, as the ability to sense an eye’s position in real time enables a computer to optimize detail rendering, and even offer cursor controls without the need for hand or head movements. But gaze tracking hardware currently is neither cheap nor small, so researchers at Nvidia have come up with a novel solution that could enable the technology to become more widespread.
Nvidia’s new gaze tracker uses a capability of common LEDs — their ability to both emit and sense light — to simplify the process of determining the eye’s position relative to a display. Like other gaze tracking systems, the Nvidia system uses a ring of infrared LEDs to project unseen light into the eye, but here, LEDs also are used for color-selective sensing from the same location. This enables the smallest and lowest-cost gaze tracking yet developed, the researchers note, while matching the accuracy and sampling rates of today’s most common solutions.
In one prototype, Nvidia uses a total of nine LEDs per eye, with three emitting IR light and six sensing the light, while a second prototype uses six LEDs per eye as both light sensors and light sources. Because the LEDs consume little power and rely on comparatively simple controller hardware and software, they cut overall latency, reduce the number of cameras needed by the headset, and remove the need for an extra image processing block within the headset’s pipeline.
Although Nvidia’s solution is performant enough to work for typical VR applications, the researchers caution that it might not be suitable for reading, neurological applications, or psychological research. While the LED system has a “good” median angular error of 0.7 degrees and a mean angular error as low as 1.1 degrees, camera-based alternatives can deliver “very high accuracy” results with error levels under 0.5 degrees. Nvidia also notes that its initial calibration phase is “comparably longer” versus other solutions, which in many cases use a “look here, here, here, and here” system to sync with eyes, and must recalibrate if the wearer’s face moves relative to the sensing hardware.
Nvidia’s gaze-sensing LED system is still in the prototype stage, so it’s not yet ready to challenge the Tobii solutions found in HTC and Pico VR headsets, or the 7invensun alternative selected for Nreal Light. But it could make its way into the next generation of VR headsets, enabling a new class of inexpensive and lightweight models with greater performance — assuming the researchers can find ways to make the calibration process fast enough not to annoy users.
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