Chapter 2: Eyes, Nose, Mouth, Ears — Variation & Stylization

Created by Sarah Choi (prompt writer using ChatGPT)

Eyes, Nose, Mouth, Ears — Variation & Stylization

For character concept artists across concepting and production. Focus: craniofacial structure, feature design, and emotional reads.

1) Purpose & Mindset

Feature design is where biology meets storytelling. The skull sets constraints; soft tissue and style dials express identity, mood, and worldbuilding. Approach each feature as a parametric system you can tune: size, proportion, axis, silhouette, plane hardness, and material response. Your job is to choose values that read at three distances: thumbnail, gameplay, and close‑up.

2) Eyes — Spheres, Lids, and Stories

Eyes are a sphere in a bony box (orbit) wrapped by upper/lower lids. Good design respects the sphere and the lid thickness.

Structure & Placement

  • Eyeball radius ≈ constant across adults; the appearance changes via lid shape, fat pads, brow, and epicanthic folds.
  • Upper lid overlap > lower lid; caruncle sits forward in ¾. Lids are caps with thickness, not lines.
  • The lid margin has a wet line (higher specular) and lashes (direction = lid curvature + growth pattern).

Variation Dials

  • Aperture shape: round, almond, hooded, up‑/down‑tilted canthi (palpebral fissure tilt).
  • Upper‑lid crease: absent/low/high; medial vs lateral fade; double folds; epicanthic presence.
  • Iris/sclera exposure: wide‑eyed (youth, fear, stylized charm) vs half‑lidded (cool, sleepy, sinister).
  • Brow/infraorbital pad volume: youthful fullness vs gaunt planar edges.
  • Distance between eyes: narrow (intense) ↔ wide (innocent); keep within credible bony landmarks.

Stylization Levers

  • Silhouette first: the arc of the upper lid and negative space of the lower lid read at distance.
  • Graphic simplification: compress the number of planes—e.g., a single highlight chip + two value steps can sell a stylized eye.
  • Iris treatment: realistic micro‑striations vs gradient disc; stylized eyes benefit from a clear value hierarchy (pupil darkest, limbal ring second, iris gradation mid, sclera lightest—avoid pure white).
  • Speculars: anchor emotion; one bold highlight communicates wetness and focus better than many small ones.

Emotion Mechanics

  • Joy: lower lid pushes up; crow’s‑feet bevel; upper lid lowers slightly.
  • Anger: brows converge/down; upper lid presses; glabella furrow.
  • Sadness: inner brow raises; upper lid arcs; lower lid lengthens.
  • Fear/Surprise: upper lid retracts, sclera shows superiorly; brows lift.

Production Notes

  • Preserve orbital loops around the eye for clean deformation.
  • Mark crease placement and whether it disappears in certain expressions.
  • Indicate shader splits: cornea refractive, sclera subsurface, wet line higher specular.

3) Nose — Wedges, Keels, and Character

The nose is a prismatic wedge with separate alar wings and a cartilage tip riding over a bony bridge. It is a silhouette anchor in profile and a plane‑break director in ¾.

Structure & Placement

  • Planes: dorsum (top ridge), side walls, and under‑plane (columella + alar base). Nostrils open backward, not straight down.
  • The rhinion marks where bone meets cartilage; the septum projects slightly under the tip.

Variation Dials

  • Bridge height/width: high & narrow ↔ low & wide; smooth vs convex/concave.
  • Tip shape: ball, point, bifid (subtle groove), droop, upturned.
  • Alar flare: narrow ↔ wide; symmetric ↔ asymmetric.
  • Dorsal profile: straight, Roman, saddle, ski‑jump.
  • Base width vs mouth width: balancing act for harmony.

Stylization Levers

  • Reduce to a wedge + under‑plane for stylized designs; let the under‑plane carry most lighting information.
  • Use the alar‑to‑cheek transition as a designed bevel—too soft reads mushy; too sharp reads hard/gaunt.
  • In graphic styles, a single contour break from brow to tip can sell the bridge; avoid over‑noodling the nostril.

Emotion Mechanics

  • Disgust: upper lip lifts; alar wings flare; tip pulls up, exposing under‑plane.
  • Anger: alar flare with sneer; nasalis activation sharpens side planes.
  • Sadness: subtle droop; less alar tension.

Production Notes

  • Model alar wings as separate volumes; avoid single‑vertex pinches at the alar crease.
  • Clarify normal/roughness maps: oily tip vs matte dorsum for realism; stylized pipelines may keep a uniform roughness.

4) Mouth — Cylinders, Corners, and Speech

The mouth sits on a dental cylinder with lips as two three‑plane forms. Corners (cheilion) are hinges that travel along the cylinder in expression.

Structure & Placement

  • Upper lip faces down & forward; lower lip faces up & forward; the tubercle creates a central down‑facing plane.
  • Philtrum is a shallow trough with peaks under the columella.
  • Mouth corner has a small pocket (commissure) that folds in smiles/frowns.

Variation Dials

  • Width: narrow ↔ wide relative to pupils.
  • Cupid’s bow: sharp ↔ soft; high ↔ low.
  • Vermilion volume: thin ↔ full; asymmetric fullness.
  • Dental projection: overbite/underbite; affects lip curve and silhouette.
  • Chin relationship: short distance (cute/youthful) ↔ long (stern/elongated elegance).

Stylization Levers

  • Corner architecture is king: a clean S‑curve into the corner reads better than lip texture.
  • Graphic mileage: two tones + a specular for the wet lower‑lip shelf sell form; avoid outlining the entire mouth in high contrast.
  • Treat the upper lip darker than lower lip in most keys (down‑facing plane vs up‑facing plane).

Emotion & Phoneme Mechanics

  • Joy: corners lift/back; lower‑lip shelf brightens; nasolabial bevel deepens.
  • Anger: corners pull laterally; upper lip thins; chin pad tightens.
  • Sadness: corners pull down; central lower lip protrudes.
  • Fear/Surprise: mouth opens vertically; upper lip retracts.
  • Speech: mark extreme phonemes (A/E/F‑V/M/L) for production; corners follow the cylinder tilt.

Production Notes

  • Maintain lip loops and a clear wet line material ID.
  • Define asymmetry allowances (smirk side, habitual tilt) that rigs can support.
  • Specify wrinkle map regions (nasolabial, mentolabial, chin pebbling) vs geometry.

5) Ears — Readable Shells with Purpose

Ears are complex internally but read via silhouette plus a few shadow pockets.

Structure & Placement

  • Landmarks: helix, antihelix (Y‑fork), concha, tragus, antitragus, lobule.
  • Tilt follows jaw angle; placement aligns with brow/top and base‑of‑nose/bottom in neutral.

Variation Dials

  • Size & projection: close to skull ↔ protruding.
  • Helix thickness/roll: thin wire ↔ broad flange.
  • Lobe: attached ↔ free; small ↔ pendulous.
  • Pointed/elfin stylization: extrude helix tip while maintaining believable cartilage logic.

Stylization Levers

  • Simplify to three shadows: concha bowl, scapha under helix roll, and the antihelix fork.
  • Keep a clean outer contour; interior linework can be minimal in stylized packages.

Production Notes

  • Model with low‑noise loops; avoid razor‑thin helix edges at low LOD.
  • Clarify ear rotation limits and collision with hair/helmets for gameplay.

6) Harmonizing Features — Proportion, Rhythm, and Theme

Features shouldn’t feel random sliders; tie them to a design theme (e.g., “knife‑like elegance,” “soft, vegetal growth,” “industrial sturdiness”). Create rhymes:

  • Sharp nose tip ↔ pointed upper‑lid peak ↔ V‑shaped cupid’s bow.
  • Wide alar base ↔ wide mouth ↔ long lower‑lid arc (friendly massing).
  • Gaunt planes ↔ thin vermilion ↔ angular ear helix.

Develop families (hero, sidekick, antagonist) by shifting 2–3 dials each while sharing a base craniofacial scheme.

7) Diversity, Age, and Body‑Type — Respectful Ranges

Design inclusive casts by treating variation as credible parameter sets:

  • Ethnic variation: bridge height/width, alar flare, epicanthic folds, lid crease forms, vermilion fullness, jaw/cheek prominence. Document ranges; avoid caricature shortcuts.
  • Age: infants—large cranium, small nose, full lips, large aperture; elderly—reduced fat pads, sharper planes, ear and nose growth with cartilage changes.
  • Body‑type: higher body fat softens infraorbital and nasolabial transitions; lower body fat sharpens zygoma, exposes tooth roots subtly under the upper lip.

Provide a taxonomy sheet with min/med/max exemplars for each feature so modeling/rigging can build reusable targets.

8) Lighting & Materials — Making Features Read

  • Use 3/4 key to cascade planes across the nose, lips, and chin; add soft fill to keep sclera from clipping to white.
  • Rim light to separate ear/cheek plane.
  • Material guidance: skin SSS; wet line (lips), tear meniscus (eyes), inner nostril—higher specular/roughness contrast.
  • Stylized pipelines: reduce pore noise; emphasize plane transitions and crisp shadow design.

9) Expression Packs — Feature‑Focused Keys

Deliver a compact set that proves deformation logic:

  • Neutral
  • Joy (Duchenne) — cheek lift, lid squeeze, dental show design
  • Anger — glabella crease, alar flare, compressed lips
  • Sadness — inner brow raise, corner downturn, lower‑lid length
  • Fear/Surprise — upper‑lid retraction, open mouth, stretched philtrum
  • Disgust — asymmetric alar lift, sneer Include phoneme extremes and note any asymmetry signatures (habitual smirk, one eyelid slightly lower).

10) Production Alignment & Handoff

  • Orthos: front/¾/profile with feature callouts; indicate crease extents and plane breaks.
  • Topology: orbit loops; nasolabial flow; lip loops; ear helix to concha loops.
  • LOD plan: preserve nose/zygoma/jaw silhouettes; push lip detail to normals at low LODs.
  • Material IDs: sclera/cornea/iris, wet line, vermilion, skin, inner nostril, ear cartilage.
  • Blendshape strategy: which emotions are geometry vs wrinkle map; define parameter ranges (max alar flare degrees, max corner lift).

11) Common Mistakes & Fixes

  • Sticker eyes: add lid thickness and corneal bulge highlight.
  • Nose painted on: model alar wings and under‑plane; show nostril opening direction.
  • Mouth outline: design corner architecture; use value, not black lines, to define lips.
  • Ear spaghetti: simplify to silhouette + three shadow pockets; reduce interior line noise.
  • Expression collapse: corners not moving along the cylinder; fix by re‑establishing mouth arc and jaw rotation.

12) Drills — Building a Feature Library

Daily (20–30 min):

  • 6 eye variations (aperture + crease) from reference, focusing on lid thickness and highlight placement.
  • 4 nose wedges (bridge/tip/alar combos) in 3 values.
  • 4 mouth corners (neutral/smile/sneer/sad) with cylinder arcs.
  • 3 ear silhouettes with interior shadow pockets.

Weekly:

  • One feature grid: 5×5 matrix exploring a theme (e.g., “knife‑like elegance”) across all four features.
  • One expression sheet proving deformation on a chosen head.

Monthly:

  • A diversity pack of 6 heads with annotated feature parameters and a mini handoff (orthos, material notes).

13) Checklists

Design: silhouette strong • planes legible • parameters documented • features rhyme with theme.

Emotion: corners travel on cylinder • lids rotate/squeeze • alar wings articulate • chin pad engages.

Production: loops clean • crease extents marked • LOD & shader notes included • blendshape ranges defined.

14) Closing

Mastery of feature variation and stylization turns faces into systems you can compose. Honor craniofacial structure, design deliberate plane changes, and document your parameters so the whole pipeline can preserve your intent—from sketch to in‑engine frame.