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Theory of Maturation in Facial Ageing
Ageing as an inevitable and natural process has most of its effects on facial appearance. Facial maturing is a dynamic procedure created with the maturing example of delicate tissues and skeletal structures. Facial ageing is a complicated modifications of skin textural changes and loss of facial volume alongside the dynamic impacts of time on the delicate tissues and profound auxiliary layers of the face.
There are numerous factors influencing human face. As development procedure happens, the adjustments in the hard and delicate tissues of the face bring about a significant change in structure of the face.
In general, as an individual ages, lower portion of his face seems to stretch, the inter-labial line plummets, and the quantity of vertical strands in the upper lip lessens. The philtral columns situated above the upper lips become less prominent and the vermillion border progressively orients to a straight line. Expansded nasolabial folds are showed up. The lips start to lose their shapes and become straight and the commissures droop appears as a frown.
A large number of the facial appearances of maturing reflect the consolidated impacts of gravity, dynamic bone remodeling and diminished tissue flexibility. Some aspects of aging are uncontrollable which are mostly related to hereditary factors. Different factors are genuinely controllable and are to a great extent the aftereffect of presentation to the components and unsafe propensities. In this chapter, we present the natural age related changes in human face. In the following, age related changes in anatomical structures are defined thoroughly.
Other ecological variables that are suggested to influence facial appearance incorporate mental pressure, diet, work propensities, sedate maltreatment, and illness which will be discussed. In chapter 5, we will present different factors effecting ageing and its impact on facial appearance thoroughly.
Structural Components of Facial Ageing
Facial ageing occurs as a result of changes in some sorts of facial tissues, consisting of skin, fat, muscle, and skeletal structure. Changes in any of these auxiliary layers have sway on different layers.
Skeletal Structure
Developing the craniofacial skeleton achieves the adjustments in the elements of bone extension and bone decay. There is a significant loss of facial skeletal structure with age and as a result a noticeable change in facial height and width. Maturing of the craniofacial skeleton might be because of changes in the elements of bone development and bone resorption; however, every single diverse bone are not influenced in a similar level since the facial skeleton resorption by ageing is heterogeneous. A large number of the facial changes while maturing are the consequence of the joined impacts on geometry and texture of the face. Bone recession prompts to more fragile skeleton as well as evacuating auxiliary help for the overlying tissues. This loss of support adds to skin drooping and detectable changes in different layers of overlying delicate tissue and skin. By age 28 the arrangement and development of the human skeletal framework in many people is terminated and physical changes happening after this formative achievement principally include bone renovating, resorption and tissue degeneration [11]. Figure 1.2 illustrates an example of bone volume loss trajectory in three different age period from young adulthood to senior adulthood of a female face.
Fat Structure
Facial aging is identified with soft tissue loss in certain areas and persistence of fat in others [13]. Fat is sorted out into fat cushions. As the face ages, the fat is vanished or misplaced. The expanded rate in fat in the upper third with respect to the rest of the midface is essentially more prominent. After some time, hard highlights, wrinkles, and creases become increasingly noticeable. As can be seen in Figure 1.3, in the face at age 35, the subcutaneous fat stores are covered by the totality given by extracellular colloidal liquids. With propelling age, dynamic loss of facial totality causes the subcutaneous fat stores and hidden delicate tissue and skeletal structures to turn out to be increasingly clear as can be seen in Figure 1.3 at age 45. Later, the fat presence in the lower third zones i.e. jowl and chin brings about the descent impression at age 55.
Skin Structure
As skin ages, the center layer of skin (dermis) gradually lessens because of collagen decay. The skin’s capacity to hold versatility and dampness likewise lessens with age. Subsequently, the skin winds up slim, dehydrated and less versatile as can be seen in Figure 1.4.
Skin wrinkling occurs at some face regions since the skin gets more slender, drier and less versatile and less ready to shield itself from harm. Sagging in other regions can occur due to a lack of elasticity as well as fat accumulation [14]. From the front the lips are thin and straight. In profile, the cheek is broken, the mandibular bend is supplanted by a jowl line, and the temple and forehead lose their foremost projection.
In order to assess the morphological effects of aging and age related changes in anatomical structures, the face can be partitioned into the upper third (brow and foreheads), center third (midface and nose), and lower third (jawline, chin, and neck) [14].
Upper third: This area is known to be the first region to show the signs of ageing. By ageing, the facial skeleton including the eye sockets, nose and maxilla continue to transform. The eye sockets expand in both women and men, and the angle of nasal bone decreases which could bring about the formation of frown lines on forehead and saggy lower eyelids. As a results of the loss of completion in the forehead, brow, and upper eyelid zones, the underlying morphological structure is highlighted and the hard layout of the skull become progressively obvious, as do the muscles of the brow and forehead. Consequently, making a progressively skeletal anatomy.
Middle third: The midface skeleton comprises the maxilla bone and left – right zygomatic bone. The degree of skeleton resorption in the midface is not uniform. Dental, maxilla and mandible transformations may bring about a general loss of stature, width and volume. In the midface, age-related loss of totality over the cheeks bring about a less sound facial extent. Loss of totality in subcutaneous fat between the muscle and the overlying skin of the lower eyelid brings these tissues into nearer closeness and makes a darker hue to the skin, bringing about a worn out eye appearance. With descending the cheeks’ fat, the nasolabial fold appears, abandoning a cheek concavity that is stressed by decrease of malar totality. Ageing additionally changes the cartilaginous, hard and connective tissue structures of nose [15]. Most of the changes in the nose as a result of ageing occur in the glabella, nasion, and medial eyelid [16]. Smoothing of the average head brings about decelerating of the nasofrontal edge, making the impression of extend nasal dorsum. The connections between the upper and lower horizontal ligaments debilitate, causing dynamic hanging of the nose tip.
Lower third: It has been observed that the aging alterations occurred in the lower third of the face mainly in chin, jawline and the neck zones had impact on the form of these components, chin, lower cheeks and neck. Aging of the mandibular part might be depicted by a few instruments, for example, fat, volume and flexibility misfortune. As the effect of gravity along with loss of elasticity continue, overabundance skin may drop off the mandible. Accordingly, internal aging is the natural and biological aging process where human gets older and associate with reducing collagen and elastin production, sagging skin as a result of decreasing fat cells and keeping moisture, appearance of wrinkles due to muscle reduction and slow production of new skin cells to replace dead skin. As skin progressively loses its elasticity, fat deposits diminishes, along with the resorption of skeletal structure, redundant skin takes place in the lower face, prompting loss of existence of the jawline appearance. As a result of displacement of facial fat to the mandibular border, the facial jowls are formed [14]. By disappearing the volume in the borders and beneath the chin, the central chin becomes prominent; however, lateral mental decay brings about ptosis of the sidelong chin, which can make the impression of chin extending when seen from the front view [13]. Chin pad ptosis, which occurs as a result of resorption in mandibular bone structure, further adds to the presence of expanded nasal dorsum length. As the fat fullness around the mandible starts to progressively diminishes, the fat around the jowl, which was used to be covered by the encompassing delicate tissues, is revealed. All in all, these transformations due to the skin laxity prompts the improvement of the trademark wrinkly neck. The deformations regarding the neck and details of lower third of the face is out of the scope of this study as our region of interest is the facial changes as a result of ageing.
Anthropometric Models
Facial ageing can be displayed utilizing anthropometric information which spotlights on separation estimations between facial component highlights. In general, face anthropometry is the investigation of estimating separations and extents on human countenances [17]. As can be seen in Figure 1.6, face anthropometry was defined by Farkas [17] in view of estimations of 57 focuses on human countenances. Five measurements between landmarks have been considered in this study characterized as: most limited distance, pivotal distance, extraneous distance, edge of tendency, and point between areas. Accordingly, 132 facial measurements were determined through which some comparing estimations on the left and right of the face were matched. This sort of estimations can be taken by hand by experts in anthropometry or more cutting-edge approaches by 3D scanners [18]. Facial estimations were taken in various ages, from adolescence to adulthood and old ages. Formerly, proportions of distances between different facial organs were measured across age. The obtained facial estimations were utilized to decide the maturing trajectory of a person through ageing pattern at a particular age and henceforth used to separate among ages and age ranges. Many studies have been performed based on this approach in the context of craniofacial development theory [19].
Based on craniofacial improvement hypothesis, cardioid strain change numerical model is described to characterize an individual’s facial development from outset to grown-up age. This numerical model deciphers a circle to follow facial development considering the varieties in radius of the circle as:
where ′ is the successive growth of the circle over time, is the leading radius of the circle, is a parameter that increments over the time, and is the initial angle formed with the vertical axis. The growth of the human head profiles utilizing cardioidal strain transformations [20] is shown in Figure 1.7.
Many studies considered the outline of the head profile or simple three-dimensional head models [21] [22] in which they displayed first outcomes exhibiting that the strategy can be correlated on 3D faces and characterized the alterations occurring during ageing process from infancy to adulthood. Nonetheless, these studies mainly focused on the importance of a head shape by simulating the face maturing dependent on geometric changes which permits just the control of the face shape.
Numerous techniques have been reported for geometry modeling of the human face [23][20] since the pioneering study of Parke [24]. It is worth noting that the anthropometric models are not best suited for the purpose of age demonstrating in grown-up and seniority faces due to the fact that there exist no compelling variations in facial shape and geometry at these phases. Moreover, this approach is only applicable for face images in frontal view since distance between landmark points are delicate to the pose and location of head presents. Furthermore, this methodology has not been performed on a huge openly accessible database, to the best of our knowledge.
Table of contents :
Chapter 1
Theoretical Background
1.1 Understanding of Facial Growth
1.2 Theory of Maturation in Facial Ageing
1.2.1 Structural Components of Facial Ageing
1.2.1.1 Skeletal Structure
1.2.1.2 Fat Structure
1.2.1.3 Skin Structure
1.3 Facial Ageing from Computer Vision Standpoint
1.3.1 State-of-the-Art on Backward Face Ageing Models
1.3.2 State-of-the-Art on Forward Face Ageing Models
1.4 Conclusion
Chapter 2
3D Face Representation Fundamentals
2.1 3D Acquisition Techniques
2.1.1 Active
2.1.2 Passive
2.2 3D Face Reconstruction and Modeling
2.3 Fundamentals of 3D Object Representation
2.3.1 3D Face Representation
2.3.1.1 Face Mesh
2.3.1.2 Face Texture UV map
2.4 3D Face Databases
2.4.1 Overview of Existing 3D Face Databases
2.4.2 Proposed 3D Face Database
2.4.3 Proposed Acquisition Protocol
2.5 Conclusion
Chapter 3
The Morphable 3D Backward Facial Ageing Model (3D B-FAM): De-ageing Model
3.1 Age Group Definition
3.2 Facial Features and Geometric Measurements
3.3 3D Face Template Construction and Selection
3.4 3D De-ageing Model Development
3.4.1 Mesh and Texture based Face Morphing
3.5 Performance Evaluation
3.5.1 Texture Similarity Evaluation (SSIM)
3.5.2 Geometric Distortion Evaluation (MSDM)
3.5.3 Face Landmarks Metric
3.6 Experimental Results
3.6.1 Face Rendering using 3D B-FAM
3.6.2 GPM Discussion
3.6.3 Performance Comparison
3.6.4 Discussion on Potential Applications
3.7 Conclusion
Chapter 4
The Morphable 3D Forward Facial Ageing Model (3D F-FAM): Ageing Model
4.1 3D Forward Ageing Model Development
4.1.1 Age Groups and Sub-groups
4.1.2 Facial Features Measurements
4.1.3 3D Face Template Construction and Selection
4.2 Performance Evaluation Mode
4.3 Experimental Results
4.3.1 3D Face Rendering using 3D F-FAM
4.3.2 GPM Discussion
4.4 Impact of Ageing on 3D Facial Verification Application
4.5 Conclusion
Chapter 5
3D Face Shape Model and the Analysis of Drug Impact on Facial Asymmetry
5.1 Impact of Factors on Facial Ageing
5.1.1 Extrinsic Factor
5.1.2 Intrinsic Factors
5.2 3D Dynamic Shape Model (FT2M)
5.2.1 Face Time Machine Matrix Model
5.2.2 Experimental Results
5.2.3 Performance Evaluation
5.3 Global Impact of Methamphetamine on Facial Appearance
5.3.1 Methamphetamine Effects on Face Asymmetry
5.3.2 Illicit Drug Addicts Database
5.3.3 Facial Asymmetry Measurement
5.3.3.1 Textural Asymmetry Assessment
5.3.3.2 Morphological Asymmetry Assessment
5.3.4 Statistical Analysis on 3D Drug Addicts Database
5.4 Drug-addict Face Simulation
5.5 Conclusion
Chapter 6
Conclusion and Perspectives
