Hot Mirror Eye Imaging for More Accurate Gaze Tracking
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Solution Overview
Problem
Existing gaze tracking systems face challenges in achieving high accuracy due to limited visibility of eye reflections and variations in eye shape, particularly in head-mounted display devices, which affect the visibility of glints and pupil positioning.
Innovation Solution
Implementing a camera field of view that captures both the eye surface and its reflection using a lens with a reflective coating, such as a hot mirror, to enhance visibility of light reflections, combined with photometric stereo techniques and machine learning models to generate accurate iris-pupil boundary models.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional camera field of view is used to capture eye images, then the system structure remains simple, but the visibility of eye reflections (glints) and pupil positioning is insufficient, reducing gaze tracking accuracy
Solution Approach 1:
The patent captures eye reflections by utilizing a different spatial dimension - the reflective surface of the display lens acts as a secondary capture plane. By positioning the camera to view both the direct eye surface and the lens reflection simultaneously, the system effectively adds a dimensional layer to eye image capture, enabling glint detection without adding physical components.
Solution Approach 2:
The display lens surface serves as an intermediary element that reflects eye images back to the camera. This intermediary reflection path enables the camera to capture glints and pupil positions that would otherwise be invisible, transforming the lens from a simple optical component into an active imaging mediator.
2Loss of information
If the camera field of view is expanded to capture both eye surface and reflection, then visibility of glints improves, but the device complexity increases
Solution Approach 1:
The display lens performs multiple functions: it serves as both the display optical element and the reflective surface for capturing eye reflections. This multi-functionality eliminates the need for separate reflective components, reducing overall device complexity while improving eye reflection visibility.
Solution Approach 2:
The system uses its own display lens to capture eye reflections, making the display component serve the dual purpose of both displaying content and enabling gaze tracking. This self-service approach eliminates the need for external auxiliary components.
3Illumination intensity
If infrared light is used to illuminate the eye, then the visibility of pupil and glints improves in the camera, but the system requires additional light source components
Solution Approach 1:
The display screen serves dual purposes: displaying visual content and emitting infrared illumination for eye tracking. By integrating the infrared backlight into the display assembly, the system achieves effective eye illumination without adding separate lighting components.
Solution Approach 2:
The infrared illumination system is merged with the display backlight structure. The same optical path and housing that deliver visible light to the user's eyes also delivers infrared light, combining two lighting functions into a single integrated system.
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
Enhances gaze tracking accuracy by improving visibility of glints and pupil positioning, enabling precise determination of gaze direction even in dynamic eye conditions.
Implementation Method 1
The light source may emit infrared light
Implementation Method 2
a reflective surface of a lens that includes a reflection of the eye... The reflective surface may be a hot mirror
Implementation Method 3
The reflective surface may be a hot mirror... a lens with a reflective coating, such as a hot mirror, to enhance visibility of light reflections
Data Source
AI summary
Systems and apparatus may implement a camera field of view capturing eye reflection and eye views for gaze tracking. A light source may emit light that reaches the surface of an eye. A camera may be implemented with a field of view that includes a portion of a surface of the eye and a portion of a reflective surface of a lens that includes a reflection of the eye. A controller may cause the camera to capture images of the eye and reflection of the eye while the light source emits light.