Virtual Anatomical Spectacle Fitting via 3D Head Model Adaptation

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Solution Overview

Problem

Current virtual fitting methods for glasses do not accurately account for anatomical adaptation to the individual shape of a customer's head, leading to unsuitable fits, especially with frames like acetate that have limited adjustability, resulting in suboptimal centering and fit issues.

Innovation Solution

A method that uses a three-dimensional head model and glasses model for virtual anatomical adjustment, involving initial positioning, refinement of the frame's bending to match anatomical specifications, and adaptation of the temples, with geometric criteria for optimal fit and distribution of forces, allowing for realistic simulation and validation of the glasses' suitability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If virtual fitting methods visualize 3D spectacle models on head models, then customer can assess glasses suitability, but anatomical adaptation and precise fitting cannot be achieved

Engineering Contradiction:
Improvevirtual fitting assessmentVSAvoidanatomical adaptation precision
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The system performs preliminary anatomical measurement and head model creation before the fitting process. By pre-capturing the customer's head geometry through 3D scanning and creating a detailed digital model, the system prepares the anatomical basis for precise virtual fitting in advance, enabling subsequent accurate frame adaptation visualization.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system creates a digital copy of the customer's head through 3D scanning and generates a virtual copy of the spectacle frame. By superimposing and adapting these digital copies, the system enables precise anatomical matching and fitting assessment without physical contact, maintaining both ease of operation and manufacturing precision.

Inventive Principle:
Principle #26Copying

2Manufacturing precision

If glasses are selected and adjusted later by opticians, then anatomical adaptation can be made, but centering assumptions change and fitting optimality is compromised

Engineering Contradiction:
Improveanatomical adaptationVSAvoidfitting process time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The system performs the anatomical adaptation process preliminarily in the virtual environment before the customer receives the actual glasses. By calculating and visualizing the required frame adjustments based on the 3D head model, the system determines optimal centering and fitting parameters in advance, eliminating the need for time-consuming post-delivery adjustments by opticians.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system provides visual feedback by superimposing the adapted spectacle model on the 3D head model, showing the customer how the glasses will fit anatomically. This feedback loop allows verification of the virtual adaptation results, ensuring centering accuracy is maintained while reducing subsequent adjustment time.

Inventive Principle:
Principle #23Feedback

3Manufacturing precision

If frame bending is performed to adapt to head shape, then anatomical fit is improved, but frame material limitations restrict adaptability

Engineering Contradiction:
Improveframe to head adaptationVSAvoidframe material adaptability
Core Design Contradiction:
Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The system applies local quality by allowing frame adaptation only in specific regions where the material permits bending. The virtual model distinguishes between adaptable frame portions (like temples and bridge) and rigid portions (like lens rims), applying geometric transformations only where material properties allow, thus maintaining anatomical fit while respecting material limitations.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The system changes geometric parameters of the frame model (positions, orientations, curvatures) within physically realistic limits. By adjusting parameters like temple angle, bridge curvature, and pad position while constraining changes within material-specific ranges, the system achieves optimal anatomical adaptation without exceeding frame material capabilities.

Inventive Principle:
Principle #35Parameter changes

4Reliability

If force distribution is optimized on contact surfaces, then wearing comfort is improved, but calculation complexity increases

Engineering Contradiction:
Improvewearing comfortVSAvoidcalculation model complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system segments the head-contacting surfaces into distinct regions (nose pads, temples, earpieces) and calculates force distribution separately for each contact zone. By dividing the complex force distribution problem into manageable segments, the system improves wearing comfort through localized optimization while keeping computational complexity at acceptable levels.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3620846A1Method and system for virtual anatomical matching of spectacles
Publication Date: 2020.03.11 FIELMANN VENTURES GMBH
  • EP3620846A1 patent drawingFigure 1~2
  • EP3620846A1 patent drawingFigure 3~4
  • EP3620846A1 patent drawing

AI summary

Method and system (50) for the virtual anatomical adaptation of spectacles to the head (2) of a person, comprising the process steps a) selecting an initial positioning of a three-dimensional spectacle model (10) of the spectacles on a three-dimensional head model (30) based on known reference points of the head model (30), b) refining the positioning of the spectacle model (10) on the head model (30), starting from the initial positioning, wherein the refinement of the positioning is carried out together with bending the frame of the spectacle model (10) to adapt to anatomical requirements of the head model (30), c) adapting the spectacle model (10) to the head model (30) by bending the temples (14), wherein the refinements and adjustments carried out in steps b) and c) are performed once or repeated for further refinement.