適合メガネフレーム開発を目的とした3次元顔形状分類

抄録

The aim of this study was to develop new eyeglass frames that fit well on most of the target population, using our original analysis method for three-dimensional human body forms.
The facial region for eyeglass frame design was from below the nose (subnasal area) to above the brow in the vertical direction, and from the tip of the nose (pronasal area) to the back of the ear in the anteroposterior direction. Face forms of 56 Japanese males were captured as plaster models because it was necessary to obtain the complete surface form, including the back of the ear. The face was represented as a three-dimensional shape model consisting of 211 data points (366 polygons) based on 61 landmarks. These landmarks were defined by anatomical/anthropological information and industrial design information for fitting eyeglass frames. Shape distances among individuals were calculated from the models for 56 × 56 pairs. A shape distribution map was calculated by analyzing the distance matrix using a multi-dimensional scaling method. The first dimension was interpreted to represent the depth of the face and the nose bridge, and the second dimension was related to the breadth of the face, height of the orbit, height of the nose, and facial flatness. Japanese male faces were classified into four groups based on the distribution map for purposes of the marketing, and the average face form was calculated for each of the four groups.
A new eyeglass frame was designed by CAD to fit each of the imported average face forms. Prototype eyeglass frames were adjusted using the actual average face models with a special soft material attached to the regions around the nose bridge and the upper ear base. These actual average face models were developed from the physical average forms using laser lithography. The soft material, made of urethane foam and silicone skin, had material properties very close to those of the human skin.
A fitting test of the new eyeglass frames was conducted for 38 male subjects. The four types of new eyeglass frames and one conventional frame were used for the experiment. Each subject put on the frames in random order and made a sensory evaluation of the fit of each frame. The compression force of the temple of the frame and the relative movements between the eyeglass frame and the face were measured for each frame.
As a result, it was confirmed that the new eyeglass frame of the correct type for each subject was designed for small compression force (half of the conventional level) and minimal slip. The score for fitting comfort was highest for the new frame of the correct type, as selected theoretically. Subjects who had larger (broader or deeper) faces and usually wore eyeglasses, however, tended to prefer a tighter frame to the new frame of the correct type.