Eye Center of Rotation Determination Without Reference Accessories
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for determining the center of rotation of the eye for personalized optical lens design are inaccurate due to the variation in eye radius among individuals, leading to significant errors in calculations, and require the use of reference accessories for image capture.
Innovation Solution
A method that captures two images of the eye in different gaze directions without using a reference accessory, using an image capture device placed close to the eye, to determine the center of rotation by identifying geometrical features of the pupil or iris and calculating the center's position relative to the device or eyewear frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a reference accessory is used to capture facial images for determining the center of rotation, then the position of the center of rotation can be determined, but the device complexity and ease of operation deteriorate due to the requirement of additional accessories
Solution Approach 1:
The invention extracts and removes the reference accessory from the measurement system, achieving center of rotation determination using only the image capture device and the subject's eye images. This eliminates the additional hardware complexity while maintaining measurement capability through alternative image analysis methods.
Solution Approach 2:
The measurement system uses the subject's own eye images and natural facial features as the measurement target, eliminating the need for external reference accessories. The subject's eye movement and pupil response serve as the self-contained measurement mechanism, improving ease of operation.
2Ease of operation
If the image capture device is placed close to the eye (e.g., 2 cm away), then the measurement can be performed in a natural posture without reference accessory, but the measurement precision deteriorates due to difficulty in capturing accurate geometrical features
Solution Approach 1:
The invention transitions from two-dimensional image plane measurements to three-dimensional spatial coordinate determination. By capturing images at multiple gaze directions and performing coordinate transformations, the system reconstructs the eye's center of rotation in 3D space, enabling accurate measurement even when the device is placed close to the eye.
Solution Approach 2:
The system changes the measurement parameters by capturing images at multiple different gaze directions (e.g., looking up, down, left, right) rather than a single fixed direction. This multi-parameter approach allows the calculation of the center of rotation by analyzing the geometric relationships across different viewing angles, maintaining precision despite close proximity.
3Ease of manufacture
If the radius of the eye is assumed as a mean value (15 mm) for calculating the center of rotation, then the calculation process is simplified, but the manufacturing precision deteriorates due to significant variation in actual eye radius among individuals
Solution Approach 1:
The system implements feedback by using the captured eye images and determined center of rotation position to calculate the individual's actual eye radius. This measured radius then feeds back into the personalized optical design process, replacing the generic mean value assumption with subject-specific data, thereby improving precision while maintaining calculation feasibility.
Solution Approach 2:
The invention performs preliminary measurement of the subject's specific eye radius and center of rotation position before the optical design calculation. This preliminary action captures individual anatomical variations, allowing subsequent personalized optical design to use accurate subject-specific parameters rather than population averages, improving manufacturing precision for customized lenses.
Data Source
Figure 1~3
Figure 4~6
Figure 7~9
AI summary
The invention relates to a method for determining a geometrical parameter of an eye (20) of a subject, comprising the following steps: a) capturing at least two images of the eye (20) while the subject looks in two different gaze directions (GD) thanks to an image capture device (30), b) identifying, on each image, the image of the pupil (10) and/or the iris of the eye (20) and determining a geometrical feature of the image (110) of the pupil and/or the iris linked to the shape of this image of the pupil and/or iris, c) determining said geometrical parameter of the eye (20) as a function of said geometrical features of the image (110) of the pupil and/or iris determined for each image of said plurality of images.