Head-Mounted Eye Tracking Calibration via Dioptric Reference
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Solution Overview
Problem
Head-mounted eye tracking devices, especially those integrated into spectacle frames, face challenges in maintaining accuracy over time due to comfort issues and frame shifting, leading to decreased tracking precision when used for extended periods.
Innovation Solution
A calibration method that involves acquiring eye data while the wearer looks at a reference direction, associating this data with the gaze direction, and recording it, with the gaze direction determined based on the dioptric function of ophthalmic lenses, and an optional calibration support with visual reference elements to enhance accuracy and comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If eye tracking devices are mounted on spectacle frames to increase comfort, then wearer comfort is improved, but tracking accuracy decreases over time due to frame shifting
Solution Approach 1:
The patent applies preliminary action by performing calibration at multiple time points (initial calibration, intermediate recalibration, and final recalibration) before the actual eye tracking measurement is completed. This proactive recalibration compensates for frame shifting that occurs during wear, ensuring accuracy is restored before it degrades the measurement results.
Solution Approach 2:
The patent implements feedback by using the eye tracking device itself to detect frame position changes and trigger recalibration procedures. The system continuously monitors its own performance degradation and automatically initiates corrective recalibration actions, creating a closed-loop control system that maintains accuracy despite frame shifting.
2Device complexity
If conventional calibration methods are used, then calibration process is simple, but tracking accuracy is insufficient for long-term wear
Solution Approach 1:
The patent performs preliminary calibration actions at multiple stages (initial, intermediate, and final recalibration) to establish accurate reference data before and during the eye tracking measurement process. This multi-stage calibration approach ensures that the system accounts for frame shifting that occurs over time, maintaining accuracy without requiring complex real-time correction algorithms.
Solution Approach 2:
The patent changes the calibration parameter timing from a single initial calibration to multiple calibration events throughout the measurement process. By introducing intermediate and final recalibration steps, the system adapts to temporal variations in frame position, effectively using time-based parameter changes to maintain measurement precision.
3Device complexity
If eye tracking devices are designed for short-term measurements, then device simplicity is maintained, but comfort for long-term wear is insufficient
Solution Approach 1:
The patent prepares the system in advance by performing initial calibration and planning for intermediate recalibration points before the eye tracking measurement begins. This preliminary preparation allows the device to maintain simplicity in design while supporting extended wear durations through pre-planned accuracy maintenance steps.
Solution Approach 2:
The patent ensures continuous accuracy maintenance by implementing intermediate recalibration during the measurement process itself. Rather than requiring the device to be perfectly stable throughout extended wear, the system continuously restores accuracy through recalibration, enabling long-term wear without sacrificing measurement quality.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method increases the accuracy of eye tracking devices mounted on spectacle frames, allowing for comfortable and precise tracking over long periods without significant accuracy loss, even when the frame shifts.
Implementation Method 1
the at least one visual reference element is a microstructured pattern designed to diffract an incident light beam towards the wearer's eye
Implementation Method 2
the gazing direction corresponding to the direction of reference is determined based on the dioptric function of the ophthalmic lenses
Data Source
AI summary
Method for calibrating a head-mounted eye tracking device, the method comprising: all acquisition step (S3), during which eye data relating to the position of the eye of the wearer are acquired by the eye tracking device while having the wearer of the head-mounted eye tracking device look in a direction of reference with regard to the spectacle lens mount, an association step (S4) during which the eye data acquired during the acquisition step are associated with the gaze direction corresponding to the direction of reference, a recording step (S5), during which the associated eye data and the gaze direction are recorded—wherein the head-mounted mounted eye tracking device comprises a spectacle frame in which ophthalmic lenses are mounted and the gazing direction corresponding to the direction of reference is determined based on the dioptric function of the ophthalmic lenses.