Spectacle Frame Measurement Using Visual Markers for Lens Centering

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Solution Overview

Problem

Existing methods for determining parameters for customizing corrective lenses are imprecise and unreliable due to difficulties in detecting frame contours from images, often obscured by reflections and complex shapes, and fail to accurately position boxings on images.

Innovation Solution

A method involving multiple image captures from different angles, using visual markers and a reference frame to determine frame parameters by optimizing a model, including steps for image processing and parameter adjustment to enhance accuracy and reproducibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Extent of automation

If frame contours are detected directly from images using luminance gradient analysis, then automated parameter determination is achieved, but measurement precision deteriorates due to obscured contours from reflections and complex shapes

Engineering Contradiction:

Improveautomated parameter determinationVSAvoidcontour detection accuracy

Core Design Contradiction:

Extent of automationVSMeasurement precision

Solution Approach 1:

The patent introduces visual markers as intermediary elements attached to the frame. These markers serve as mediators between the imaging system and the frame parameters, providing clearly detectable reference points that are not obscured by reflections or complex frame shapes. The markers enable automated detection while maintaining high precision by decoupling the detection process from direct frame contour analysis.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the detection parameter from analyzing frame contour luminance gradients to detecting marker positions and orientations. This parameter transformation allows the system to automatically determine frame parameters through marker geometry analysis, which is much more reliable than direct contour detection in the presence of reflections and complex shapes.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If multiple image captures from different angles are taken, then measurement reliability improves, but measurement time increases

Engineering Contradiction:

Improvemeasurement reproducibilityVSAvoidtime for multiple image captures

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The visual markers are designed to be self-descriptive, containing encoded information about frame parameters within their geometry. By attaching markers that inherently encode the required measurement information, the system eliminates the need for complex multi-angle imaging and processing, achieving both high reliability and speed through the markers' self-contained information.

Inventive Principle:

Principle #25Self-service

Data Source

PatentEP3857298B1Automatic establishment of parameters necessary for constructing spectacles

Publication Date: 2025.09.17 ESSILOR INTERNATIONAL(COMPAGNIE GENERALE D OPTIQUE)

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AI summary

The invention relates to a method for automatically establishing parameters in order to centre and/or personalise corrective lenses for spectacles, comprising the following steps:- taking images of the frame from different viewing angles, - defining an initial model of the frame in a reference system based on a set of predefined initial parameters, projecting a region of interest in the images, - comparing the projections and evaluating a similarity between said projections, - modifying at least one of the parameters of the model and reiterating the steps until a maximum level of similarity between the projections is obtained, - deducing the at least one of the parameters from the model associated with the projections which have the maximum level of similarity.