Aesthetic unity
The face is divided schematically into aesthetic units and sub-units to take account of different features of the skin and contours. The aesthetic units of the face are the eyes, the forehead, the temples, the cheeks, the lips, the chin, the ears and the nose.
For example, skin color, skin thickness and the number and size of skin pores differ from one aesthetic unit to another (e.g. eyelid and nostril). Sub-units are represented in simplified form as two-dimensional surfaces in the three-dimensional face. The units and sub-units are delimited by natural dividing lines.
Dividing lines
Dividing lines are the intersection curves of two surfaces that run at a certain angle to each other (e.g. transition from the bridge of the nose to the slope of the nose). A similar principle is used in computer graphics, for example, to represent a face using polygons (see “Non-uniform rational B-splines”, NURBS for short).
Other dividing lines are formed by wrinkle lines (e.g. nasolabial fold at the transition from the cheek to the mouth). Dividing lines are suitable for planning the incision, as scars in the border area of units or subunits appear particularly inconspicuous.
