Parametric design for custom-fit eyewear frames

Abstract

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. In this paper 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.

Keywords: 3D scan; Algorithm; Anthropometrics; Customized product; Design; Eyewear; Face; Fit; Parametric design.

Fig. 1

Primary facial landmarks for parametric eyewear design.

Fig. 2

Facial dimensions for eyewear design and body-product relationship establishment.

Fig. 3

Eyeglasses components and a glossary of eyewear design terms.

Fig. 4

Positioning the eyewear frame using Face wrap, Pantoscopic tilt, Front surface, and Vertex distance. (a). Extracting the Forehead contour (a) from connecting Glabella (1) and both Eyebrow Lateral points (17&18). Construct the Face Wrap contour (A) using the halved angle. (b). Constructing pantoscopic tilt (B) as a referential line using Nasian tilt (b) based on Glabella (1) and Sellion (0). (c). Constructing a curvature surface for face wrap with Face Wrap (A) and Pantoscopic tilt (B). (d). Adjust the distance between face wrap surface and the Pupil (c). The green surface is shifted away from the defaulted red surface.

Fig. 5

Eyewear components construction exemplified on half side in parametric modeling. (a). Front frame contour based on related landmarks and dimensions. (b). Hinge added based on Eyebrow Lateral point (17) and Temple point (31). (c). Lens cavity contour by offset adjustive parameters from frame contour. (d). Arm contour based on related hinge point and ear landmarks. (e). Nose pad contour based on Sellion (0), Nasal Root point (3), and adjustive point on frame. (f). Half frame contour constructed and assembled.

Fig. 6

Body parameters are entered in the algorithm to generate a correct size and fit. (a). Body parameters: The landmarks are acquired as point coordinates with exampled Pupil point (7) highlighted in green. The dimensions (three examples showed) can be either extracted in algorithm by computing the distance between two points, or manually entered the numerical values after digitally measured in Rhino, as shown in yellow panel notes. (b). The defaulted eyewear frame structure in customized size and proportions only after the body parameters are entered, with adjustive parameter values settled as default or clear (e.g., zero radius for edge fillet).

Fig. 7

Adjustive parameters of Vertex Distance and Arm Breadth are set differently for comfort and functionalities. (a). Adjustive Parameters of Vertex Distance and Arm Breadth are settled as minimum values. The front frame tightly sits on face with a distance to pupil at 8 mm; the two arms are shrunk inwards 1 mm slightly sit on scan data. (b). Adjustive Parameters of Vertex Distance and Arm Breadth are settled as moderate and maximum values respectively. The front frame is in moderate distance to pupil at approximately 14 mm; The two arms are shrunk inwards 3 mm which can grab the head more tightly.

Fig. 8

Adjustive parameter of Nose Pad contour can be fine-tuned to achieve different nose bridge comfortableness. (a). Adjustive parameters of Nose Pad contour is settled as uniform curve type which interpolates exactly on landmarks with no other factor added. (b). Adjustive parameters of Nose Pad contour are settled as chord curve type with a stretch factor to provide a relatively shallower contour for relaxed fit. (c). Adjustive parameters of Nose Pad contour are settled as SQRT curve type with a stretch factor to provide a relatively deeper contour for tight fit.

Fig. 9

Adjustive parameters for Front Frame and Arm style elements. (a). Front frame narrow and slim style, center bridge arched, small edge radius, narrow and slim hinge parts. (b). Slim arm style with small blade shape factor. (c). Front frame oversized and bulky style, center bridge more straightened, large edge radius, wide hinge parts. (d). Wide arm style with large blade shape factor.

Fig. 10

A global view of parametric design algorithm demonstrated on the mannequin model. (a). The layout of parametric design is composed of Rhino CAD software for visualizing design variations on the left side, and Grasshopper interface for coding the parametric algorithm and adjusting parameters on right side. (b). The layout of the parametric algorithm in the Grasshopper coding interface. Each block encodes its processors (batteries) for constructing eyewear components.

Fig. 11

Local views of each block containing processors in parametric design algorithm. (a). Parametric processors (algorithm) for front frame, hinge, and lens cavity. (b). Parametric processors (algorithm) for Arm. (c). Parametric processors (algorithm) for Nose bridge. (d). Parametric processors (algorithm) for the entire frame union.

Fig. 12

Anthropometric data (landmarks and dimensions) for two subjects on scan data. (a). Front view of landmarks and dimensions for Subject A. (b). Side view of landmarks and dimensions for Subject A. (c). Top view of landmarks and dimensions for Subject A. (d). Front view of landmarks and dimensions for Subject B. (e). Side view of landmarks and dimensions for Subject B. (f). Top view of landmarks and dimensions for Subject B.

Fig. 13

The generated parametric eyewear wireframes shown on the two subject face scans. (a). Parametric design outcome of eyewear wireframe for Subject A, a Caucasian male with a head circumference of 62 cm, at 97% as a percentile based on the CAESAR database. (b). Parametric design outcome of eyewear wireframe for Subject B, an Asian female with a head circumference of 54 cm, at 33% as a percentile based on SizeChina database.

Fig. 14

Completed CAD eyewear frame 3D models for two subjects. (a). Final CAD modeling and rendering of parametric eyewear frame for subject A. (b). Final CAD modeling and rendering of parametric eyewear frame for subject B.