CHING' STUDIO
Parametric Design for
Custom-fit Eyewear Frames
Publication of the Study:
Tian, Y., & Ball, R. (2023). Parametric design for custom-fit eyewear frames. Heliyon, 9(9), e19946. https://doi.org/10.1016/j.heliyon.2023.e19946
More than half of the people on the planet use eyewear to correct or protect their vision. Eyewear products that fit poorly cause discomfort, dizziness, or blurred vision. One method to improve fit is to create custom-fit eyewear frames on an individual basis. We propose a new parametric design method to customize the eyewear frames based on individual 3D scanned data of head-and-face measurements. We take the eyeglasses frame as the case study to establish the landmark-product relationship and develop the parametric algorithm in Rhino/Grasshopper software. The results of the case study can generate custom-fitted eyeglass frame models for the two selected subjects, one 33% percentile Asian female and one 90% percentile Caucasian male. The future study will continue validating the eyewear frame fit and optimizing the parametric design method.
01
Anthropometric Study
Designing custom eyewear requires a working knowledge of the relationship between the anthropometry of the head and face and eyewear design methods. Through Anthropometric study, we identified a Landmark Taxonomy including 32 primary head-and-face landmarks and 10 dimensions, defined eyewear frame components, and established a Body-Product Relationship for further algorithmic modelings.
Landmark Taxonomy
Based on the preliminary landmark research, we identified 32 primary facial landmarks that can be captured through 3D scanning.
In addition to the 32 primary facial landmarks, 10 secondary dimensions including distances, contours, and angle values are required to further establish the relationship between the face shape and the eyeglass frame components
A Glossary of Eyewear Frame Design Components
Body - Product Relationship
An eyewear frame is comprised of a set of components, the front frames, the lens cavities, the hinge (between frames and arms), the two arms, and the nose bridge. Designing a customized eyeglass frame requires establishing the body-product relationship between the facial landmarks and the eyewear components. The eyewear frame dimensions can be calculated using numerical formulas and geometric relations based on facial landmarks and dimensions.
Fit Factor Analysis
02
Achieving a good fit in eyewear design requires understanding the physical fit factors. Four fit factors that need to be satisfied in eyewear design are quantitative fit, contact fit, interference fit, and ventilated fit. Analyzing these fit factors can help us “decompose” the eyewear components and establish a proper Body-product relationship.
Quantitative Fit
Body landmarks and dimensions regulate product dimension quantitatively to guarantee the proper size of coverage.
Face breadth >= Frame length >= Eye orbit length
Nose height >= Frame height >= Eye orbit height
Nose bridge width = Nasal root breadth
Contact Fit
Product structure should conform to the body surface curvature.
e.g., Nose pad conforms to the nasal root curve.
Interference Fit
Product dimension is designated to be slightly smaller than the actual body measurements to provide a secure snug/tight fit and achieve the “dynamic fit”.
e.g., Arm width slightly smaller than head breadth
Ventilated Fit
Product surfaces in certain areas are supposed to be “away” from the body surface for correct functionality and comfort.
e.g., Vertex Distance (Frame and lenses should NOT contact or wrap on face)
03
Parametric Algorithm Development
An eyewear frame is comprised of a set of components, the front frames, the lens cavities, the hinge (between frames and arms), the two arms, and the nose bridge. Designing a customized eyeglass frame requires establishing the body-product relationship between the facial landmarks and the eyewear components. The eyewear frame dimensions can be calculated using numerical formulas and geometric relations based on facial landmarks and dimensions.
03
Parametric Algorithm Walkthrough
04
Parametrization for Customization
Frame Edge Fillet Radius
Vertex Distance
Frame Height
Another important criterion of customization design is to provide adjustability that can cater to the user’s unique needs and preferences. adjustable parameters are utilized for further tuning the product dimensions.
Vertex distance, frame height, hinge size, etc.,
can be adjusted through parametric sliders or numerical value controls. Meanwhile, these adjustive parameters add more attributes to fulfill the comfort, functionality, and aesthetics.
Arm Breadth
Hinge Size
Lens Cavity Size
Pilot User Test
05
We recruited two adult subjects within the research team for a pilot test for 3D scanning and algorithmic eyewear generating. Prior to the scanning process, the subjects' head and face landmarks were identified through palpation and the location was marked using an eyeliner pencil.
One subject is a Caucasian male with a head circumference of 62cm, accounting for the 97% percentile according to the CAESAR database. Another subject is an Asian female with a head circumference of 54cm, at 33% according to the Size China database.
To summarize, this study explores a newly developed parametric design method accompanied by 3D scan technology and anthropometric knowledge. The experiment case on custom-fit eyewear frames verifies the feasibility and potential of broader design opportunities for wearable products. We expect that this method can be adopted in a larger field of applications and motivate design development facing the new chapter of Mass Customization.