3D Eye Tracking Framework for Depth of Focus
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Solution Overview
Problem
Conventional eye tracking systems struggle to accurately determine the depth at which a user is focusing within the real-world environment, leading to potential motion sickness or vertigo when computer-generated images are rendered at an incorrect depth.
Innovation Solution
The implementation of a computer-implemented method and eye tracking system that uses a three-dimensional eye tracking framework to track the user's interpupillary distance and visual axes in real-time, calculating the depth of focus by determining the vergence in space between the visual axes of each eye.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional eye tracking systems track only line of sight using Purkinje reflections, then the system complexity is low, but the measurement precision of depth of focus is insufficient
Solution Approach 1:
The patent transitions from 2D line-of-sight tracking to 3D visual axis tracking by adding depth dimension. Sensors are positioned at multiple locations around the eye to capture elliptical projections of the iris, enabling calculation of visual axis orientation and depth of focus through three-dimensional geometric relationships.
Solution Approach 2:
The patent introduces an intermediary mathematical model that relates the observed elliptical iris projections to the underlying visual axis orientation. This model serves as a bridge between the sensor measurements and the depth of focus calculation, enabling accurate depth estimation without direct measurement.
2Measurement precision
If sensors are positioned angularly offset to capture elliptical iris projections, then the depth of focus measurement accuracy improves, but the device complexity increases
Solution Approach 1:
The patent divides the eye tracking function across multiple sensors positioned at different locations around the eye. Each sensor captures a portion of the elliptical iris projection from its specific angle, and the combined data from all sensors enables comprehensive 3D visual axis reconstruction.
Solution Approach 2:
The patent makes the sensor system multi-functional by using the same sensors to simultaneously capture both the 2D position of the pupil center and the 3D orientation of the visual axis. The elliptical iris projections serve dual purposes: determining gaze direction and calculating depth of focus.
3Measurement precision
If the system tracks visual axes instead of just line of sight, then the depth of focus determination accuracy improves, but the computational complexity increases
Solution Approach 1:
The patent performs preliminary calculations of visual axis orientation and vergence angle based on the captured elliptical projections. These pre-computed parameters are then used to determine depth of focus, breaking down the complex computation into manageable sequential steps that reduce overall computational burden.
Solution Approach 2:
The patent creates a computational model that replicates the geometric relationships of the visual system. By copying the anatomical and optical relationships into a mathematical framework, the system can simulate and calculate depth of focus without requiring complex real-time measurements of all eye parameters.
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 allows for a significantly higher accuracy in determining the user's depth of focus, thereby reducing the likelihood of motion sickness or vertigo caused by misaligned computer-generated images.
Implementation Method 1
Conventional eye tracking systems illuminate the user's eyes with near infrared light and then track the user's eye movements by observing reflective patterns that are formed from the near infrared light
Data Source
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AI summary
Techniques for implementing eye tracking using various real-time computational solutions to a three-dimensional eye tracking framework. An exemplary eye tracking system for a NED device includes sensors that are directed toward and angularly offset from a user's eyes in a manner that causes circular features (e.g., irises and/or pupils) of the user's eyes to appear elliptical within sensor planes of the individual sensors. An iris and/or pupil of an eye will appear circular when the eye is looked at straight on (i.e., perpendicular to an optical axis of the eye's lens) but elliptical when observed from an angular offset. The eye tracking systems and methods disclosed herein exploit these principles to track movements of the user's eyes with a higher degree of accuracy than conventional eye tracking systems.