Eye Visual Axis Measurement Without Manual Calibration
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Solution Overview
Problem
Existing eye tracking systems require time-consuming and error-prone manual calibration methods to determine the angular offset between the visual and optical axes of the eye, often necessitating extra hardware and software.
Innovation Solution
A method involving the use of an image sensor and a spatial orientation sensor mounted on a rigid frame, where the relative orientation between the sensors remains fixed, allowing for the calculation of the angular offset by tracking the user's gaze at different head poses while maintaining focus on a fixed point, utilizing quaternion and matrix mathematics to refine the visual axis orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual calibration methods are used to determine angular offset, then measurement precision can be achieved, but time consumption and error rate increase
Solution Approach 1:
The system performs automatic calibration without requiring manual intervention. The image sensor captures eye images at multiple head poses, and the processing system automatically computes the angular offset by analyzing the relationship between optical axis orientation (from image sensor) and visual axis orientation (from gaze point fixation), eliminating the need for manual calibration procedures while maintaining measurement precision
Solution Approach 2:
The patent replaces manual mechanical calibration procedures with an automated optical sensing system. Instead of physical alignment procedures, the system uses image sensors to capture eye orientation at different head poses and computationally determines the angular offset, substituting mechanical manual adjustment with optical-electrical measurement and processing
2Measurement precision
If manual calibration methods are used to determine angular offset, then measurement precision can be achieved, but error rate increases
Solution Approach 1:
The system uses feedback from multiple image captures at different head poses to iteratively refine the angular offset calculation. By capturing eye images at multiple poses and analyzing the consistent relationship between optical axis and visual axis orientations, the system feedback-adjusts the calibration parameters to improve reliability and reduce errors compared to single-point manual calibration
Solution Approach 2:
The automated system performs self-calibration by automatically analyzing the relationship between optical axis (from image sensor) and visual axis (from gaze point) orientations across multiple head poses, eliminating human error in manual alignment while maintaining or improving measurement precision through computational analysis
3Adaptability or versatility
If image sensor and spatial orientation sensor move relative to user's head, then adaptability improves, but measurement complexity increases
Solution Approach 1:
The system is designed to work with dynamic head movements. The image sensor and spatial orientation sensor can move relative to the user's head while maintaining their relative orientation to each other. The system captures images at multiple head poses and uses the spatial orientation data to compensate for head movement, enabling adaptability to various head positions while managing complexity through computational correction
4Measurement precision
If multiple head poses are used for calibration, then measurement precision improves, but calibration time increases
Solution Approach 1:
The system performs continuous capture of eye images at multiple head poses in a seamless manner. By continuously capturing images during natural head movement rather than requiring discrete static positioning, the system maintains useful action continuity and can obtain multiple calibration points more efficiently, improving precision without proportionally increasing calibration time
Data Source
AI summary
Disclosed herein are methods for determining an angular offset between a visual axis of a person's eye and an optical axis of the eye, or an angular offset between a line of sight of the eye and the optical axis of the eye.