Chapter 2: Rigging / Skinning Considerations

Created by Sarah Choi (prompt writer using ChatGPT)

Rigging / Skinning Considerations for Character Concept Artists

Why concept artists must think like riggers

Concept art sets not only the look of a character but also the plausible motion envelope the character can inhabit. Every silhouette choice, seam, and prop anchor either cooperates with deformation or fights it. When concept artists surface rigging and skinning concerns early—joint ranges, twist distribution, deformation risk, attachment logic—they prevent rework and preserve the intended acting, gameplay readability, and performance budgets. This article treats concepting and production concepting equally, showing how to design for motion, story, and interaction while partnering closely with Design, Animation, Tech Art, Narrative, UI, and Audio.

Core vocabulary you’ll use in cross‑team conversations

Rig = the skeleton + controllers that drive deformation. Skinning = vertex weighting to bones or deformers. Joint chain = ordered bones that define arcs (e.g., spine, tail). Range of motion (ROM) = safe angles a joint can reach in play. Twist distribution = how a long limb shares axial rotation across multiple bones to reduce candy‑wrapper artifacts. Deformation risk zones (DRZ) = locations prone to collapse, shearing, or texture stretch (e.g., shoulders, elbows, groin). Corrective = shape or pose‑space morph used to fix a bad bend. Proxy = simplified mesh for tests before final topology.

Metrics first: scale, reach, and collision envelopes

Begin every character with explicit metrics: standing height, shoulder width, arm span, and key reach distances (door handles, weapon grips, UI diegetics). Provide mini‑orthos showing neutral pose (A/T) and maximum gameplay poses (reach overhead, kneel, sprint, aim). Add collision envelopes—capsules around limbs, skirt/coat volumes, backpack clearance—to demonstrate how the character will pass through doors, ladders, vehicles, and crowd spaces. Tech Art can turn these into early ragdoll or physics proxies; Animation can test locomotion cycles; Design can verify interactable heights. Your paintovers should annotate where cloth or armor can safely compress or must remain rigid to avoid clipping.

Human ROM heuristics for believable motion

While engines and rigs vary, use grounded heuristics when composing silhouettes so Animation isn’t forced into impossible poses. Shoulders tolerate ~90° abduction without scapular motion; overhead reaches require the torso to side‑bend and rotate. Elbows flex ~140° but only extend to ~0°–5°; keep armor breaks away from the cubital crease. Wrists flex/extend ~70°/70° with ~20°–30° radial/ulnar deviation; avoid hard bracers that cross the wrist fold. Hips flex ~120° and extend ~20°; deep crouches need extra seat/inguinal clearance. Knees flex ~140°; heavy greaves should steer seams above and below the patella to avoid shearing. Ankles dorsiflex ~20° and plantarflex ~45°; thick boots need rocker geometry. Treat these as directionally correct constraints and show compensations (torso lean, foot turnout) in your expression poses.

Mapping anatomy to topology: designing for deformation

Good skinning starts with concepted seam lines that anticipate edge‑flow. Mark twist and bend zones visually: spiral wrappings on forearms suggest distributed twist; layered plates at shoulders imply sliding coverage over deltoid bulge; segmented collars telegraph clavicle elevation. For soft‑surface characters, paint tension paths along Langer‑like lines where skin stretches (pectoralis‑biceps line, iliac crest to femur). For clothed figures, place seam breaks along natural folds—back of knee, inside elbow, under scapular plane—so Texture and Modeling can hide corrective shapes. In production concepting, include grayscale “rig thinking” overlays showing where you expect helper bones (clavicle, scapula, twist joints) and where blendshapes will fire.

Deformation risk zones and how to design around them

Shoulder complex. Devours budgets if ignored. Design shoulder armor in floating layers or with soft gaskets that tuck during overhead reach. Avoid single‑piece pauldrons that bridge torso to arm; use straps or sliding tracks that suggest relative motion. Elbow/knee. Don’t paint decals that must remain rectangular across deep flexion; propose panelization that rotates around the joint rather than across it. Groin/seat. Long coats, armored skirts, and holsters collide in crouches. Show back‑panel slits, scallops, or hidden gussets. Neck/jaw. Tall collars should bevel away under the mandible; propose hinge notches for head tilt. Wrists/ankles. Taper rigid elements before the crease; introduce bellows or laces to imply expansion.

Twist distribution and candy‑wrapper prevention

Any limb that rotates axially (upper arm, forearm, thigh, calf) benefits from multiple twist joints. As a concept artist, visualize that distribution: spiral trims, helical cables, or layered wraps that naturally rotate across the length rather than at a single point. This visual story supports Tech Art’s decision to insert twist bones and tells Animation how rotation should appear to flow.

Cloth, hair, tails, and capes: rig‑friendly silhouettes

Secondary elements can sabotage rigs if silhouettes ignore clearance. When proposing capes or long hair, provide two states: calm and action. In the action state, show how the element shortens or splits (cape with swallowtail notches, hair bound with rings) to minimize foot or weapon entanglement. For tails and tendrils, design joint spacing hints: thicker base, tapering segments, and periodic rings that imply where FK/IK controllers live. For skirts and coats, stage layered hems that stagger lengths to avoid synchronized collision popping and to keep readability in isometric or long‑shot cameras.

Props, holsters, backpacks, and wearables

Every attach point is a rigging problem in disguise. Show precise anchors (grommets, buckles, rails) and the motion they permit. A thigh holster should angle so the pistol clears the knee during sprint; a two‑point rifle sling needs shoulder comfort and chest avoidance in crouch. Backpacks require spine clearance—design a curved lumbar pad—and shoulder strap separation to preserve clavicle motion. Show how hard shells float over soft underlayers to allow breathing and twist.

Partnering with Animation: performance and acting

Supply an acting sheet alongside beauty frames. Include extreme body language (panic turn, triumphant reach, wounded limp) to prove the design deforms with feeling. Where you foresee corrective shapes—cheek puff in grin, elbow bulge in flex—call them out so Animation can plan pose libraries. If the character’s power set changes silhouette (inflating gauntlet, stone skin), paint transitional states and the timings you imagine; this informs trigger conditions for corrective blends.

Partnering with Tech Art: budgets, controllers, and LOD

Discuss early the bone count budget, physics slots (cloth, hair, props), and deformation method (linear vs dual‑quaternion). Design controller visibility: a mech pilot with ten tentacles implies spline‑IK chains and UI rig toggles; simplify the number of independently animated bits where gameplay doesn’t need them. Consider LOD: at distant cameras, busy straps and micro‑panels become shimmering noise. Offer a clean LOD silhouette frame that Tech Art can target for bone reduction and baked folds.

Partnering with Design & Narrative: motion supports mechanics and story

Mechanics define motion priorities. If Design emphasizes vaulting and mantling, free the chest and hips; if stealth crouch is primary, bias seam allowances at knees and seat. Narrative arcs can justify wear patterns and asymmetries that also improve deformation (e.g., favored sword arm has slimmer bracer and articulated elbow). Use costume motifs to telegraph mechanical states: a ratcheting collar for berserk mode (head stability), glowing tendon lines along forearms for power‑up (readable twist), or an expandable rib vest for deep breaths (stamina UI).

Partnering with UI & Audio: readable states and hooks

UI needs unambiguous silhouettes for status icons and diegetic displays. Integrate readable, rig‑safe panels where UI can anchor holograms or LEDs without crossing major bends. For Audio, propose mechanical notches and fabric choices that naturally “speak” in motion—ring clusters that chime during rolls, carbon plates that clack at footfall—so Foley has clear cues that don’t depend on impossible deformations.

Interaction‑forward posing: design around hands and grips

Hands are the most animated part after the face. When designing grips (hold, push, pull), ensure handle diameters and trigger reaches match plausible MCP/PIP flexion. Show alternative grip states for a single prop (relaxed carry, ready, recoil compensation) and annotate knuckle clearance from adjacent armor. For two‑handed interactions, paint the elbow path and torso twist so Animation can keep wrists neutral and avoid forearm shear.

Express tests: five poses that de‑risk a design

Before handing off, produce a one‑sheet with five reality checks: 1) over‑head reach; 2) deep crouch/aim; 3) long sprint stride; 4) sit/ride with back contact; 5) fall/roll recovery. In each, mark where cloth compresses, plates separate, and props shift. If something breaks, adjust the concept: add articulation gaps, move anchors, or simplify mass.

Creature, mech, and hybrid bodies

For non‑humans, define gait and primary action first (flight burst, pounce, coil‑strike). Then distribute twist along the spine or tail with visible segment cues. For digitigrade legs, stagger armor plates so the hock can fold without clipping the calf. For winged characters, show fold states: full span, half tuck, full tuck, and backpack mode, each with notch geometry to guide feather or panel overlap. Mechs benefit from rig‑thinking decals that indicate hinge axes and telescoping limits; add cable slack routes to avoid impossible stretch.

Textures and materials that help skinning

Materials can hide or reveal stretch. Matte fabrics forgive UV scaling; mirror‑finish metals magnify shearing. Place high‑frequency prints away from major bends; put noisy textures where you expect minimum deformation. Use anisotropic patterns (rib knits, corduroy) to visually confirm bend direction and to help Tech Art tune tension maps.

Handoff package: what to include

Deliver a neutral‑pose ortho with joint center guesses; a ROM board of the five express tests; callouts for DRZs with proposed correctives; seam maps and armor overlap logic; anchor diagrams for all attachments; and an LOD‑ready silhouette sheet. Include a brief on intended controller philosophy (e.g., “forearm twist distributed across two helper joints; cape has two simulation tiers; tail uses spline IK with four controls exposed to animators”).

Common pitfalls to avoid

Designing single shells that span two moving parts; placing logos across deep flexion zones; ignoring backpack‑to‑cape conflicts; forcing 1:1 real‑world hinges in stylized bodies; loading too many small danglers that demand physics; treating footwear like rigid blocks (no rocker); and promising animation beats (e.g., dramatic kneel) the costume cannot physically allow.

Quality bar: motion is part of style

In pre‑production, set a motion manifesto with Animation and Tech Art. Decide how much squash/stretch or secondary jiggle belongs in your world. Your concepts should then prove that style under deformation—not just at rest. A design that looks excellent only in the key art but fails the five express tests isn’t shippable.

Final thought

Concept artists who design with rigs in mind protect story moments, gameplay clarity, and production time. By baking ROM heuristics, twist distribution, and deformation‑safe seam logic directly into your art, you empower Animation to act, Tech Art to simplify, Design to balance, and UI/Audio to communicate—so the character the player meets on screen feels inevitable, alive, and reliable in motion.