Chapter 4: Understructures for Silhouette

Created by Sarah Choi (prompt writer using ChatGPT)

Understructures (Petticoats & Hoops) for Silhouette in One‑Piece Systems

Orientation for Concept and Production Artists

Understructures are the hidden architecture that determine how a one‑piece dress, robe, or gown occupies space, moves, and reads on camera. For concept artists, they set the silhouette family (column, bell, A‑line, trumpet, panier) and the performance verbs (float, throb, sweep, clatter). For production artists, they define load paths, closure logic, collision risk, and materials cost. Treat the support as a separate asset layer with its own metrics, constraints, and storytelling—your over‑garment is only as believable as the shape beneath it.

Vocabulary and Use Cases

Petticoat: A fabric underskirt that adds volume via layers, ruffles, or horsehair braid; softens outlines and supports hemlines without visible struts. Ideal for A‑line and romantic bell silhouettes. Crinoline: Historically horsehair‑reinforced petticoat; modern usage often means a stiffened petticoat made of net, tulle, or organza. Reads crisp and springy. Hoop Skirt / Cage Crinoline: A skeletal frame (steel, plastic, or carbon hoops) hung from a waistband; produces maximum volume with minimal weight and reduces fabric drag. Reads architectural and ceremonial. Bustle Pad / Bum Roll: A padded crescent or roll at back waist/hip that throws fabric rearward; used for bustle or fishtail silhouettes and to balance trains. Pannier / Side Hips: Side‑extending frameworks or pads creating lateral width; good for courtly, theatrical, or factional silhouettes that require stage‑like presence. Corded Petticoat: Rows of cord stitched into channels add stiffness and concentric wave control; sits between soft petticoat and hoop in behavior.

Silhouette Mechanics: Where the Volume Lives

Volume originates either in compressible mass (layered fabric) or spanning members (hoops/boning). Compressible systems damp motion and flutter; spanning systems pivot and oscillate with discrete frequencies. Place volume where the camera benefits: an even bell favors 3rd‑person readability; back‑weighted mass showcases capes and trains; side‑weighted mass establishes court hierarchy. In one‑piece systems, ensure the waist seam or princess lines can bridge cleanly over the support without torquing the bodice.

Load Paths, Comfort, and Safety

Weight should transfer to the iliac crest via a stable waistband or yoke; suspenders or bodice integration prevent slippage. Use wide, brushed waistbands to increase friction and distribute load. Vent heat with mesh panels where the understructure meets the body. For stunts and long sessions, quick‑release closures (hook bars or side‑release buckles) are safer than laced center‑back only. Flag any rigid ring diameters wider than doorway metrics; provide a folded transport configuration.

Materials and Stiffness Profiles

Hoop Materials: Spring steel (durable, crisp arc), poly/HDPE (light, forgiving, less memory), carbon fiber (ultra‑light, expensive, must be padded at joins). Fabric Layers: Net/tulle for loft at low mass; organza for translucent crispness; muslin for cost‑efficient bulk; voile for soft collapse. Edge control via horsehair braid yields a firm hem line that catches light. Map stiffness vertically: firmer lower tiers act like a shelf; softer upper tiers cushion and hide struts. For hoops, set ring spacing closer near the hem to prevent scalloping.

Integration with One‑Piece Bodies

When bodice and skirt are continuous, decide whether the support belongs to the dress (attached underskirt) or is a separate equipment layer. Attachments simplify dressing but complicate laundering and rigging; separates enable reuse across variants. If the waist has no seam (princess construction), anchor petticoats to an internal waist stay so the outer shell can float. For empire lines, shorten supports so their apex aligns under bust; for sheaths with surprise flare (mermaid/trumpet), use a bustle pad plus targeted godets instead of a full cage.

Motion and Camera Reads

Petticoats produce micro‑ripples; hoops produce hinge‑like swing and phase‑lag between rings. In over‑the‑shoulder cameras, a back‑weighted bustle helps silhouette separation without occluding feet. For isometric views, avoid excessive lateral panniers unless the game space is generous. On stairs and ladders, specify front flare reduction (narrower front rings, soft upper tiers) to minimize clipping. Provide three motion poses—idle sway, stride apex, spin—so cloth settings and collision capsules can be tuned per zone.

Venting, Slits, and Access

Match vent locations in the outer garment to gaps or soft zones in the understructure. For thigh slits, cut away or soften the corresponding petticoat wedge. For hoop skirts, break the two lowest rings at the front quarter with hidden connectors to allow kneel/sit poses. Include portals—small plackets in petticoats—for pocket access or utility belts in diegetic designs. Anchor slit tops with bar‑tacks; line vent edges to prevent snagging on hoop tapes.

Train Management

Trains require a distinct tail logic. Pair a bustle pad with a soft petticoat so the train launches cleanly and doesn’t collapse into the legs. For cathedral‑scale trains, extend the last hoop backward into an oval or add a trailing demi‑hoop that supports fabric as it exits the body. Provide a wrist loop or discreet hitch points for gameplay states (running, stealth). Communicate how the train docks to backpacks, capes, or weapon sheaths to avoid system conflicts.

Patterning and Construction for Production Artists

For petticoats: draft concentric tiers with increasing circumference; join with staged ruffle ratios (e.g., 1.5×, 2×, 3×) to avoid abrupt step‑offs. Insert corded channels to stabilize waveforms. Use net + lining sandwiches where comfort and opacity matter; keep scratchy net away from skin. For hoops: tape channels to a strong vertical web (twill tape or bias‑bound seams). Provide ring length tables per size and label ring positions (H1, H2, …). Design closures at side‑front to avoid the spine and to ease dressing. All stress points receive bar‑tacks; all ring ends are filed/sleeved.

Modularity and Variant Logic

Build a kit: one base petticoat, a snap‑on lower tier, a detachable bustle pad, and an optional cage. This lets the same hero dress scale from travel mode (soft, narrow) to ceremony (wide, majestic) in narrative beats. Color‑coding tapes and embroidery can telegraph rank or power state without altering the outer shell. For NPC economies, reduce ring count and replace with corded petticoats to save geometry and sim cost.

Cultural and Historical Respect

Understructures have deep roots across cultures—European hoops and bustles, East Asian quilted skirts and layered under‑robes, various ceremonial pads and side‑hips. When drawing inspiration, study original function (modesty, climate, dance, ritual space‑making) and preserve that logic. If you stylize, document which aspects are homage versus invention, and engage sensitivity review early. Avoid collapsing diverse traditions into a generic “court look.”

Rigging and Cloth Sim Collaboration

Hoops are best represented as rigid or semi‑rigid colliders with limited spring, while petticoats are soft‑body or high‑damping cloth. Provide collision proxies for rings (torus/arc chains) and for the body (pelvis, thighs, shins). Author constraint maps that are stiffer at ring channels and more permissive between them. If budget is tight, bake ring influence into an outer‑skirt rig with pendulum constraints rather than full sim. LODs: remove inner tiers and reduce ring count; keep hem silhouette with a heavier horsehair braid.

Sound, FX, and Story Signals

Understructures have a sound signature: net rustle, organza whisper, hoop clack. Use that sonic cue in FX notes—add glitter drift from stiff hems for magic states, dust puffs for desert travel, or rain bead‑off at rings. Contrasting petticoat flashes can code faction colors during spins. For stealth, specify matte tape bindings and soft nets to quiet movement.

Ergonomics: Sitting, Riding, Combat

Design sit logic: hoops need hinged breaks or soft upper tiers; petticoats compress, but add panels of stretch net at the seat for comfort. For riding, front rings should rise and the back should extend like a half‑dome. In combat silhouettes, front volume should clear high knees and side lunges; combine a moderate bustle pad with tapered front supports.

Maintenance, Laundering, and Storage

Petticoats launder; hoops wipe down. Specify removable covers for pads; store hoops horizontally to prevent ovalization. Include replacement ring kits and repair tapes in the diegetic world logic if maintenance is a theme. Document fold‑down methods and case dimensions for travel sequences.

Troubleshooting the Shape

If the hem scallops between rings, increase ring count or add a stiffened facing. If the dress “tents” and reveals rings, add a thin top petticoat as a diffuser. If sway feels chaotic, add mass at the hem (beads, braid) or increase damping at ring channels. If the bodice rides up, check that the support’s waist is lower than the garment’s waist or add an internal waist stay to decouple loads.

Deliverables Checklist (Paragraph Style)

Provide a support spec that states ring diameters and spacing, materials per tier, closure locations, waistband width and reinforcement, stiffness map (from soft to firm), modular add‑ons, collision proxy notes, LOD plan, sitting/riding strategy, and maintenance logic. Describe how understructure and outer garment couple at the waist and how vents and slits align with soft zones. Include three motion paragraphs keyed to idle, stride, and spin.

Closing Principle

Understructures are the unseen stage upon which your one‑piece system performs. When you engineer the base with intention—balanced load, tuned stiffness, smart access—the outer dress needs less fabric, moves more expressively, and tells a clearer story. Architect the silhouette from the inside out, and your gowns will command space without fighting physics.