Handheld Spectacle Measurement via Vertical Parallax Correction
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Solution Overview
Problem
The existing methods for measuring geometrical-physiognomic parameters for corrective eyeglass lenses are cumbersome, restrictive, and require a bulky, non-ergonomic device with a vertical base column to ensure accurate alignment, leading to vertical parallax errors and a lengthy measurement process.
Innovation Solution
A flexible measurement method using a handheld mobile device that captures frontal images with potential vertical offset, correcting for vertical parallax errors through calculation of the absolute vertical angle of observation, allowing for precise measurement of parameters like eye height and pantoscopic angle without the need for a base column, using inclinometers or artificial horizon devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a base column with vertically movable image capture device is used to ensure accurate alignment and avoid vertical parallax errors, then measurement precision is improved, but device complexity and ergonomics deteriorate
Solution Approach 1:
The patent replaces the mechanical base column system with a computational approach. Instead of using a physically constrained vertically movable camera on a base column, the invention uses a handheld mobile device combined with digital image processing and calculation algorithms to correct vertical parallax errors. The processing means compute the actual vertical positions of pupils by analyzing the captured image and applying corrections based on the known vertical position of the datum and geometric relationships, thereby substituting mechanical alignment precision with computational accuracy.
2Measurement precision
If a base column with vertically movable image capture device is used to ensure accurate alignment, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The patent replaces the cumbersome mechanical base column system with a lightweight handheld mobile device that can be easily held and positioned by the optician. The device combines a standard mobile camera with processing capabilities to capture images and compute measurement data, eliminating the need for the optician to operate a heavy, fixed base column mechanism while maintaining measurement accuracy through computational correction of vertical parallax.
3Measurement precision
If a base column with vertically movable image capture device is used to avoid vertical parallax errors, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent incorporates a datum element with a known vertical position that is pre-positioned on the frame before the measurement process begins. This preliminary placement of the datum provides a reference point that enables the processing means to calculate vertical positions of other features (such as pupils) directly from the captured image, eliminating the need for time-consuming vertical alignment adjustments of the camera on a base column.
Solution Approach 2:
The patent replaces the time-consuming mechanical process of vertically positioning a camera on a base column with instant computational processing. The processing means analyze the captured image and calculate the vertical positions of pupils and other features by applying geometric relationships and corrections based on the known datum position, providing rapid results without manual alignment adjustments.
4Ease of operation
If a handheld mobile device is used for image capture, then ease of operation is improved, but measurement precision deteriorates due to vertical offset and parallax errors
Solution Approach 1:
The patent compensates for the vertical offset and parallax errors introduced by using a handheld mobile device through computational correction. The processing means calculate the vertical position of the camera relative to the datum and use this information to correct the positions of features in the captured image, thereby eliminating the precision degradation that would normally result from handheld operation.
Solution Approach 2:
The patent makes the measurement system adaptable to various handheld devices and operating conditions by implementing a universal computational correction algorithm. The system can handle images captured from different vertical positions and angles, as long as the datum element is visible and its known position can be used for reference, thereby providing measurement capability across a wide range of practical handheld scenarios.
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
Enables rapid, accurate, and ergonomic measurement of geometrical-physiognomic parameters, improving the convenience and precision of corrective lens fitting while reducing the complexity of the measurement protocol.
Implementation Method 1
a frontal image is captured by means of an image capture device
Implementation Method 2
an inclinometer fitted to the image capture device, adapted to supply a signal representative of the value taken by the attitude angle
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The method comprises a step of capturing a substantially frontal digital image of the face of the wearer provided with at least the frame (10), by means of a camera (1), and a step of calculating the geometric/physiognomic parameter (H, THETA) based on the processing of the captured image. The calculation of the geometric/physiognomic parameter (H, THETA) comprises the identification, on this image, of the image of a predetermined noteworthy point (RC), directly or indirectly associated with the wearer's face or with the frame, and takes into consideration a quantity representative of the absolute vertical angle of observation (GAMMA) that makes a line of observation (DO), connecting the pupil (7) of the camera (1) to the noteworthy point (RC), with its projection on a horizontal plane (PF).