Dynamic Gaze Tracking Marker Repositioning

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Solution Overview

Problem

Current gaze-tracking systems require user-specific calibration and suffer from temporal latency and inaccuracies due to fixed markers, limiting their application to desktop usage and introducing motion artefacts.

Innovation Solution

A system and method that dynamically repositions a luminous marker to coincide with the pupil center, using feedback from relative positions of the corneal reflection and pupil center, allowing for accurate and calibration-free gaze tracking with reduced latency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If fixed markers are used for gaze tracking, then the system is simpler to implement, but temporal latency increases and accuracy decreases

Engineering Contradiction:
Improvesystem simplicityVSAvoidtemporal latency
Core Design Contradiction:
Device complexityVSLoss of time

Solution Approach 1:

The patent applies the dynamics principle by transitioning from fixed markers to dynamically repositionable markers. The marker position is continuously adjusted based on feedback from corneal reflection and pupil center position detection, allowing the marker to move in real-time with eye movements. This dynamic adjustment eliminates temporal latency caused by fixed marker identification delays while maintaining system simplicity.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements feedback by using the detected relative positions of corneal reflection and pupil center to control the marker repositioning. The control unit receives position data, calculates the difference, and adjusts the marker position accordingly. This closed-loop feedback mechanism eliminates the need for complex calibration procedures and reduces temporal latency by continuously adapting to eye movements.

Inventive Principle:
Principle #23Feedback

2Device complexity

If fixed markers are used for gaze tracking, then the system requires less computation, but measurement precision decreases due to threshold distance inaccuracies

Engineering Contradiction:
Improvecomputation requirementsVSAvoidgaze direction accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent applies dynamics by making the marker position adaptive rather than fixed. The marker is repositioned based on real-time feedback from corneal reflection and pupil center detection, allowing precise gaze tracking without relying on threshold distance calculations. This dynamic approach eliminates the inaccuracy inherent in fixed marker systems where the marker must be identified within a threshold distance of the pupil center.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent uses feedback to continuously adjust the marker position based on the detected relative positions of corneal reflection and pupil center. This closed-loop control enables precise measurement of gaze direction without the computational burden of analyzing multiple video frames for marker identification, thereby improving measurement precision while maintaining reasonable computation requirements.

Inventive Principle:
Principle #23Feedback

3Measurement precision

If multiple markers are used to improve accuracy, then gaze direction precision increases, but device complexity and computation power requirements increase

Engineering Contradiction:
Improvegaze direction accuracyVSAvoidnumber of markers and computation
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies the extraction principle by isolating the essential function of marker identification to a single dynamically repositionable marker. Instead of using multiple fixed markers and performing complex interpolation, the system uses one marker whose position is directly controlled based on corneal reflection and pupil center detection. This extraction of the core function to a single marker reduces device complexity and computation requirements while maintaining high measurement precision.

Inventive Principle:
Principle #2Taking out (Extraction)

4Measurement precision

If user-specific calibration is required, then measurement precision improves, but adaptability decreases and limits application to desktop usage

Engineering Contradiction:
Improvegaze tracking accuracyVSAvoidfreedom of head movement
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent applies self-service by enabling the system to automatically adjust the marker position based on real-time detection of corneal reflection and pupil center without requiring user-specific calibration. The feedback mechanism allows the system to self-calibrate for each user's eye characteristics and head position, eliminating the need for manual calibration procedures while maintaining high measurement precision and enabling freedom of head movement.

Inventive Principle:
Principle #25Self-service

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 system achieves high accuracy and fast convergence, enabling gaze tracking with freedom of head movement and suitability for consumer applications without the need for user-dependent calibration.

Implementation Method 1

determine, from the image, a corneal reflection of the marker on the eye of the observer

Methodology Applied
Scientific EffectCorneal reflection: Reflection

Implementation Method 2

determine, from the image, a corneal refraction of the center of a pupil of the eye of the observer

Methodology Applied
Scientific EffectCorneal refraction: Refraction

Data Source

PatentEP2549914B1System and method for tracking the point of gaze of an observer
Publication Date: 2019.06.05 KONINKLIJKE PHILIPS NV
  • EP2549914B1 patent drawingFigure 1~2
  • EP2549914B1 patent drawingFigure 3~4
  • EP2549914B1 patent drawingFigure 5

AI summary

A system for tracking the point of gaze of an observer observing an object comprises a camera for recording an image of an eye of the observer, comprises a means for providing a luminous marker, and means for analyzing the image of the eye to determine the reflection of the marker on the eye and the centre of the pupil. The relative positions of the corneal reflection of the marker and the pupil centre are measured. The marker is repositioned, in dependence on the determined relative positions, to improve correspondence between the corneal reflection of the marker and the pupil centre.