How Apple’s Face ID Uses Infrared Technology for Secure Authentication
Apple’s Face ID system is one of the most advanced facial recognition technologies in consumer devices today, but contrary to common belief, it does not rely on LiDAR. Instead, it uses a specialized TrueDepth camera system that leverages infrared (IR) technology to create a highly accurate 3D map of the user’s face. This system consists of three key components: a dot projector, an infrared camera, and an IR flood illuminator—all working together to enable secure biometric authentication.
How Face ID Creates a Depth Map
The dot projector plays a crucial role by projecting over 30,000 tiny infrared dots onto the user’s face in a structured pattern. These dots do not simply mark points on the face but rather serve to create a depth map by measuring how the dots distort when they land on different facial contours. The way the pattern warps across the surface of the face allows Face ID to determine the precise 3D structure of an individual’s features.
Once the dots are projected, the infrared camera captures an image of this pattern along with the user’s face. Unlike traditional cameras that rely on visible light, the use of infrared ensures that Face ID works effectively in low-light or even complete darkness. Meanwhile, the IR flood illuminator enhances this process by emitting invisible infrared light, making it possible to detect faces even when there isn’t enough ambient light for the human eye to see.
Face ID Security and Liveness Detection
After capturing the infrared image and depth map, the iPhone’s neural engine processes the data, comparing it to the stored Face ID profile. If a match is detected, the device unlocks almost instantaneously. Face ID also includes liveness detection, ensuring that the person in front of the phone is a real, living individual and not a photo, video, or 3D mask. By looking for subtle facial movements—such as blinking or slight muscle twitches—Face ID can reject spoofing attempts and confirm the presence of a real human.
Apple has designed Face ID to be significantly more secure than Touch ID. The odds of a random person successfully unlocking your iPhone with Face ID are approximately 1 in 1,000,000, compared to 1 in 50,000 for Touch ID.
Why Face ID Doesn’t Use LiDAR
Despite the inclusion of LiDAR scanners in recent Pro models of the iPhone, Face ID does not use LiDAR for facial recognition. While iPhone LiDAR is excellent for depth sensing in photography, augmented reality (AR), and 3D scanning, it is not optimized for biometric authentication. LiDAR measures distance by calculating the time it takes to bounce laser pulses off surfaces, a fundamentally different approach to creating a 3D surface by observing the distortion of projected dots, as is done with the TrueDepth system. Other sources say the TrueDepth approach is more accurate than LiDAR. I am curious to get the opinion of our readers on this assertion.
This YouTube video gives a great overview and visual explanation of the iPhone Face ID system.
Face ID Adapts to Facial Changes
By combining structured infrared light projection and depth-sensing technology, Face ID ensures both security and convenience while adapting to gradual facial changes, such as growing a beard or aging. For sudden changes, such as shaving off facial hair or wearing a mask, Apple has refined Face ID’s ability to focus on the upper half of the face, particularly the eyes. However, using Face ID with a mask is slightly less secure than full-face recognition.
While LiDAR continues to revolutionize AR applications and 3D mapping, Face ID’s use of infrared depth mapping remains the gold standard for smartphone biometric security. As depth-sensing technology evolves, it will be interesting to see how Apple further refines facial recognition while maintaining its balance of speed, security, and adaptability.
Lidar News reports on iPhone LiDAR regularly, such as Lidar on the iPhone Explained. Subscribe using this LINK or below to stay up-to-date.
Image Attribution:
“Apple Face ID infrared dot projector” by Phiarc is licensed under CC BY-SA 4.0. Source: Wikimedia Commons.
