a wrinkle in time, part II: static forms

This post is Part II of a series on wrinkle types. Part I focused on wrinkles caused by repeated facial expressions – dynamic wrinkles. Part II will focus on another class of wrinkles: static wrinkles. While static wrinkles might not seem as exciting as dynamic expression wrinkles, they are just as important to consider when applying to your character. As stressed in Part I, every line tells a story.

static “wrinkles”

Static wrinkles are set in place on the skin; they are visible with or without facial movement. Static wrinkles  can be caused by repeated expressions, gravitational forces, and loss of skin elasticity.

NOTE: In Part I, we already covered how dynamic expression lines can turn into static lines as well. We will therefore only cover the non-expression-based lines in this document.

There are various types of static skin creases. Because the technical definition of “wrinkle” is still debated, it is important to know that the following list is a mix of wrinkles and skin characteristics. Technicalities aside, each of the following categories is useful to study if you want to understand basics of skin texture and shape changes:

  • microrelief
  • atrophic crinkling rhytids
  • permanent elastoic creases
  • sleep creases
  • gravitational folds

microrelief

Microrelief is the fine, irregular geometric patterns that cover the skin surface. Microrelief characteristics come together to create skin texture. 

Microrelief quality is affected by aging and multiple environmental factors.

“The innate polygonal pattern becomes more anisotropic with increasing age.”

(Wiki) Anisotropy (/ˌæn.ə-, ˌæn.aɪˈsɒtr.əp.i/) is the property of being directionally dependent, which implies different properties in different directions, as opposed to isotropy.
Basically – microrelief starts off as randomized geometric patterns in younger skin; however, as the skin ages, the surface lines are deformed on more of a directional basis. This concept makes sense, as over time, more environmental factors stress and influence the properties of the skin.

Why should artists care?

Microrelief is one of the foundations of skin texture. Being familiar with the basic structure and geometric patterns of the skin surface as well as how it changes over time will allow you to create realistic texture in your art. This type of information is especially critical to artists and researchers working on digital humans.

atrophic crinkling rhytids 

Atrophic crinkling rhytids are the fine lines that surround your skin. If mircorelief is considered the first layer, atrophic crinkling rhytids (ACRs) are the next level. ACRs are typically parallel lines that form above the microrelief. ACRs get deeper and saggier over time, and are more apparent when the skin is thin.

closeupatrophic

Why should artists care?

As mentioned in the “microrelief” section, the fundamental details of the skin are crucial in creating realistic skin textures, especially with the new digital human trend. Atrophic crinkling rhytids are the next layer after microrelief. Their parallel patterns provide a less chaotic structure than microrelief.

Screen-Shot-2020-05-12-at-5.40.50-PM Screen-Shot-2020-05-12-at-5.35.09-PM

permanent elastoic creases

Permanent elastoic creases (PECs) are wrinkles that form when the skin is in a certain position but stretch when the skin is taut. They can be creases around your lips or on your wrists, elbows, neck, etc.

PECs get worse and more defined as you age. You can reduce elastoic wrinkles by reducing repetitive movements. For example, if you have lines around your lips from regularly drinking with a straw or lines across your neck from looking down at your phone or computer, decreasing how often you drink with straws or look down will decrease the speed at which your elastoic wrinkles deepen.

permanentelastoic

Why should artists care?

At points of joint intersection or areas of skin that require regular bending (or puckering, like the lips), elastoic wrinkles can be used to illustrate behavioral history. You can adjust the depth of these wrinkles based on the angle of movement, the frequency of movement, and the age of the character. For character artists, these wrinkles are what you would want to put in the topology.

sleep creases

Sleep creases form over time from habitually sleeping on one side. They typically form on the lateral side of the forehead but occur in other parts of the face as well – basically, anywhere that can be squished while lying sideways. If you see a deep wrinkle that cannot be explained by muscle movement, consider sleep creases.

Anthony Hopkins has a deep vertical crease on the left half of his forehead. This line cannot be explained by any type of muscle movement, but it can be explained by longterm pressure from repetitive sleeping positions. If you ever wanted to know about Anthony Hopkins’s preferred sleeping side: He likes to sleep on his left, which is arguably the best side to sleep on– especially for your gut. Nice job, Hopkins!

Thanos on the other hand, who has equally distributed sleep creases on both sides of his forehead, clearly has no favorite side.

I see a lot of character models that include sleep creases. Based on the way in which these creases are being applied (usually bilaterally with even depth), it is likely most artists are using sleep creases as cosmetic accessories rather than truly understanding their function.

Anthony Hopkins's sleep creases

Why should artists care?

If you really want to get into detailed story building, you can get down to the minutia of everyday life, like sleeping habits and environmental conditions.

gravitational folds

Gravitational folds are skin folds that droop from gravity. Older and thinner skin is more susceptible to this type of sagging. Drooping eyelids and jowls are types of gravitational folds. 

nasolabial fold

Why should artists care?

Understanding how skin characteristics affect facial features can help you paint a more realistic portrait. You can deform targeted areas of the skin based on conditions such as age and skin thickness.

Takeaways

With all of the different layers of the skin and varying depths/types of lines, you can read facial movement and tell even more detailed stories about environment, genetics, age, and lifestyle.

P.S. Enjoy this picture of Thanos and how he could theoretically treat his wrinkles. Thank you, Rodion Vlasov for letting me use your Thanos fan art.

thanos.7