Eye Tracking Illumination Calibration for Accurate Gaze Estimation
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Solution Overview
Problem
Existing eye tracking systems suffer from inaccuracies due to uneven illumination by light sources, leading to errors in gaze estimation, particularly in wearable devices.
Innovation Solution
A controller adjusts the intensity of multiple light sources based on their illumination contributions, ensuring even illumination by processing images acquired with different subsets of light sources, using a calibration method to determine and set light-source-control-signalling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple light sources are used to illuminate the user's eye, then the illumination coverage is improved, but the evenness of illumination deteriorates due to variations in light source brightness
Solution Approach 1:
The patent applies local quality by adjusting the intensity of each light source individually based on its specific illumination contribution to different regions of the eye. The controller determines which light sources illuminate which portions of the eye and adjusts their intensities locally to achieve uniform overall illumination, rather than applying a uniform intensity setting to all light sources.
Solution Approach 2:
The patent changes the intensity parameter of each light source based on measured illumination contributions. The system measures the illumination level provided by each light source and adjusts their intensity parameters dynamically to compensate for variations, transforming the system from static uniform illumination to dynamic adaptive illumination with uniform result.
2Illumination intensity
If light source intensity is increased to improve image brightness, then the illumination level is improved, but the accuracy of gaze estimation deteriorates due to uneven illumination
Solution Approach 1:
The patent implements feedback by measuring the actual illumination level provided by each light source and using this information to adjust their intensity. The system continuously monitors illumination contributions and adjusts light source intensities accordingly, creating a closed-loop control system that maintains optimal illumination for accurate gaze estimation.
Solution Approach 2:
The patent performs preliminary measurement of illumination contributions from each light source before conducting gaze tracking. This preliminary characterization of each light source's illumination pattern allows the system to pre-calculate appropriate intensity settings that will achieve uniform illumination during actual use, improving gaze estimation accuracy from the start.
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
This approach enhances the evenness of illumination, improving the accuracy and precision of gaze tracking by reducing variations in image brightness caused by uneven light source brightness.
Implementation Method 1
a plurality of light sources that are arranged to illuminate a user's eye
Implementation Method 2
the reflection of the light is captured by an image sensor
Data Source
Figure 1~2
Figure 3~4A
Figure 4B~4C
AI summary
An eye tracking system (300) comprising: a plurality of light sources (310-319) that are arranged to illuminate a user's eye when the eye tracking system is in use; and a controller (325). The controller (325) is configured to: receive a first-image of a surface (333), acquired while the surface (333) is illuminated by a first set of the plurality of light sources; receive a second-image of the surface, acquired while the surface (333) is illuminated by a second set of the plurality of light sources, wherein the second set of light sources is different to the first set of light sources; process the first-image and the second-image to determine an illumination contribution of one or more of the light sources (310-319); and determine light-source-control-signalling (334) for one or more of the light sources (310-319) based on the determined illumination contribution of the one or more of the light sources, wherein the light-source-control-signalling (334) is for setting the intensity of light provided by the respective light sources (310-319) when the eye tracking system (300) is in use.