Eye Tracking Calibration via Scene Understanding in AR Headsets

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Solution Overview

Problem

Augmented reality (AR) systems face challenges in maintaining accurate eye tracking calibration due to deformations, movements, and environmental changes in head-mounted display (HMD) devices, leading to reduced effectiveness in rendering convincing, life-like AR images.

Innovation Solution

The system employs scene understanding to continuously calibrate eye tracking by detecting real-world objects, using sensors and processors to determine gaze directions and calibrate the eye tracking operation based on differences, ensuring proper alignment and focus adjustment through varifocal systems and waveguide uniformity correction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If eye tracking calibration is performed using fixed initial settings, then the system is simple to implement, but the accuracy deteriorates due to HMD deformations and movements

Engineering Contradiction:
Improveeye tracking accuracyVSAvoidcalibration system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The calibration system transitions from static initial calibration to dynamic continuous calibration. The system continuously updates eye tracking parameters by detecting real-world objects and comparing their rendered positions with actual sensor detections, allowing the calibration to adapt to HMD deformations and movements during use.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system implements feedback loops where eye tracking data and object detection data are continuously compared. The difference between rendered object positions and actual sensor detections feeds back into the calibration process, automatically adjusting parameters to maintain accuracy without user intervention.

Inventive Principle:
Principle #23Feedback

2Reliability

If continuous calibration using scene understanding is implemented, then eye tracking accuracy is maintained under HMD movements, but the computational load and processing time increase

Engineering Contradiction:
Improvecalibration stabilityVSAvoidprocessing energy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system performs calibration selectively rather than continuously at full intensity. It triggers calibration updates based on detected changes in the environment or HMD state, performing partial calibration operations only when necessary to maintain accuracy, thus reducing overall computational load.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The system performs preliminary object detection and rendering to predict where objects should appear before actual eye tracking measurement. This preliminary action allows the system to pre-calculate expected positions and compare them with actual detections, streamlining the calibration process and reducing real-time processing requirements.

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If the system uses multiple sensors and processors for comprehensive scene understanding, then calibration accuracy improves, but the device complexity and manufacturing difficulty increase

Engineering Contradiction:
Improvegaze direction accuracyVSAvoidsystem assembly difficulty
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The system uses multi-functional sensors that serve multiple purposes. For example, cameras and sensors used for basic AR rendering and environment mapping are also utilized for eye tracking calibration and object detection, eliminating the need for separate dedicated calibration hardware and simplifying manufacturing.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The calibration function is merged with the existing AR rendering pipeline. The same processors that handle graphics rendering and the same sensors that capture the environment are used for calibration tasks, combining multiple functions into unified processing streams to reduce hardware complexity.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentUS11353955B1Systems and methods for using scene understanding for calibrating eye tracking
Publication Date: 2022.06.07 META PLATFORMS TECHNOLOGIES LLC
  • US11353955B1 patent drawing
  • US11353955B1 patent drawing
  • US11353955B1 patent drawing

AI summary

A system can include one or more processors that determine a first position of an object in view of a user of a head mounted display (HMD) and a first gaze direction towards the first position. The object can be detected by one or more sensors. The one or more processors detect that the user is gazing at the object. The one or more processors determine, responsive to detecting that the user is gazing at the object, a second gaze direction based on at least a second position of one or more eyes of the user of the HMD provided via an eye tracking operation of the HMD. The one or more processors calibrate, based at least on a difference between the first gaze direction and the second gaze direction, the eye tracking operation of the HMD.