Chapter 2: Proportion Passes & A / B / C Sets

Created by Sarah Choi (prompt writer using ChatGPT)

Proportion Passes & A/B/C Sets

From Brief to Package: The Character Concept Pipeline (Ideation → Iteration → Finals → Handoff)

Proportion passes and A/B/C sets are the most reliable way to pressure‑test a character’s role, readability, and rig viability without committing to surface detail. Rather than chasing the perfect drawing, you deliberately manufacture contrast—typically in 30% deltas—to show stakeholders how different body plans affect class reads, animation posture, and equipment fit. This article frames proportion work as a shared language between concept and production so that decisions made at thumbnail scale remain true at rig, cloth, and gameplay scale.

Start with Proportion Targets You Can Defend

Every proportion pass begins by translating the brief into measurable targets. Role and camera distance define what must be legible first: a tank needs a low center of gravity and a wide base that remains readable at 10% on‑screen height; a striker needs long arcs and taper that sell speed at mid‑shot; a healer needs an equipment‑led read that keeps hands and tools clear of the torso. You should also establish a default height band in engine units and a head‑count model for artistic shorthand. If the project’s human baseline is 7.5 heads tall, decide whether the character’s A model sits at baseline, with B pushing mass up or down by roughly 30% in one or two axes, and C testing the limit of legibility while still living on the same skeleton family. These targets become your north star for the pass.

What a 30% Delta Actually Means

The “30% delta” is a practical rule of thumb, not a rigid law. It means that the visual impression of a key proportion shifts by about one‑third so that differences are obvious at a glance but still plausible inside a shared rig and costume set. If shoulder span is 100 arbitrary units in your A model, the B or C variants might move to 130 or 70. If torso‑to‑leg ratio is 1:1 in A, consider 1.3:0.7 and 0.7:1.3 as B and C. The delta should be applied to only a few priority levers at a time—height, limb length, shoulder‑to‑hip relationship, head size, neck length, foot length, and hand span—so that you can isolate cause and effect. When everything moves at once, you learn nothing. When one or two dimensions move by 30% against a constant ground plane and eye level, you get clean comparisons that stakeholders understand.

Ideation: Blocking the First Proportion Sweep

In the ideation phase, work in simple, ortho‑friendly poses and flat values. Start with a neutral A body that expresses the brief without flourish. Then create B and C in a mirrored file with a locked scale bar so ground contact and head height remain comparable. Apply your 30% deltas to the agreed levers. If you widen shoulders, keep hip width constant to study power posture; if you lengthen legs, keep torso height constant to examine stride promise. For non‑human or hybrid anatomies, choose analogous levers: tail length, wing span, digitigrade vs. plantigrade reach, or carapace depth. Even in early ideation, mark knee, elbow, and ankle centers; these landmarks help production estimate deformation and IK ranges later.

Once the first sweep exists, miniaturize the models to 5–10% of final on‑screen height and check class read. If your C silhouette is the most charismatic but collapses at distance, you have learned that your delta overshot legibility and can back off to a 20% shift along that axis. Conversely, if A, B, and C look suspiciously similar at gameplay scale, your deltas are too conservative and you should push further or change which lever you are moving.

Iteration: Building A/B/C Families, Not Orphans

Iteration is where proportion work becomes systematic. Instead of isolated A/B/C triplets, build A/B/C families. An A family might keep overall height constant while exploring shoulder‑to‑hip extremes; a B family might hold shoulder span constant while lengthening legs; a C family might hold the pelvis and spine while upsizing head and hands to amplify expression and interaction readability. Across families you are searching for a “hero proportion grammar” that can be replicated across skins, armor tiers, and faction dialects without re‑rigging. Exploration artists should annotate each family with intent notes that describe how the delta supports role verbs like brace, lunge, aim, cast, and guard. Production artists should flag any family whose deltas force skeleton changes or cause collision nightmares with capes, belts, or backpacks.

While you iterate, maintain a constant environment plate behind your figures—a neutral gray and a noisy plate—to simulate real gameplay backgrounds. This keeps proportion decisions honest. Many designs that look elegant on white fall apart when the values have to fight a busy arena or forest canopy. If a 30% head‑size delta is the only way to keep a healer readable in foliage, that is production gold you want to discover now, not during beta.

Camera‑Aware Proportion Testing

Because cameras rewrite silhouette, proportion passes must be camera aware. For over‑the‑shoulder third‑person, back massing and shoulder skyline dominate, so shoulder span and backpack depth deserve a dedicated delta sweep. For isometric or tactics views, leg‑to‑torso ratio and cape area drive read; head size can drop but hand span cannot if attacks telegraph through hands. For first‑person projects with visible bodies, forearm length and chest depth control self‑occlusion and rhythm in the lower screen. Build micro A/B/C triplets for each camera band so decisions are grounded in the view that actually ships.

Integrating Equipment and Costume Without Faking the Data

Proportion passes should not be camouflaged by costume tricks, but they cannot ignore equipment. A healer’s staff length, a tank’s shield size, and a striker’s blade span all change the balance of the silhouette. The trick is to represent equipment as clean graphic primitives—rectangles for shields, cylinders for staves, wedges for blades—so that the relationship between body and tool remains explicit. If your 30% shoulder‑span delta fails because a square shield becomes a billboard that erases the hip line, the lesson is not to hide the shield; it is to adjust either shield aspect or elbow clearance so the role read returns. Production appreciates proportion files where equipment is abstracted yet accurately positioned; it lets them project collision volumes and socket spacing early.

Talking to the Rig: Skeleton Families and Safe Limits

A/B/C sets live or die on rig compatibility. Early in iteration, map each triplet to a skeleton family and document whether it fits without scaling the rig disproportionately. Many studios will tolerate up to roughly 10–15% uniform scale from a base rig before deformation and animation reuse suffer; beyond that, you need a new skeleton or you pay in QA debt. Your 30% deltas in surface proportion should respect these interior limits. Lengthening legs by 30% relative to torso may be compatible if the thigh and shin adjust evenly and IK ranges still resolve stairs and crouches; exploding arm length by 30% on a shooter may break reload cycles and hand alignment on weapons. Good proportion pages declare which deltas are “skin deep” and which imply retargeting or bespoke animation.

Finals: Converging on a Hero and Locking Ratios

Finalization begins when one A/B/C family consistently wins read tests and survives rig scrutiny. Convert that family into a proportion‑final sheet with front, side, and back silhouettes at equal scale on a common ground plane. Lock major ratios numerically: total height in engine units, shoulder span to hip span, pelvis height to leg length, head height to body height, and hand span to head width. Include a micro lineup of neighbors—friendly and enemy classes—to show contrast at a glance. If the project supports skinning or armor tiers, include one example overlay that proves your hero proportion still reads with 20–30% added mass in armor or cloth. This is the moment to capture “do not break” rules, such as minimum neck length for head aim offsets, maximum shoulder protrusion before clipping a cape rig, or minimum foot length for stable step cycles.

At this stage, add a controlled value pass that groups large masses and clarifies balance, but resist surface texture. The goal is a shape hierarchy that production can carry into orthos and 3D block‑ins without guessing. If marketing needs color early, include a small swatch strip beside the proportion sheet rather than painting the figure; this keeps attention on form.

Handoff: Packaging Proportions for Downstream Use

A strong handoff bundles proportion logic with the assets that make it actionable. Provide the proportion‑final sheet, the winning A/B/C exploration page, and a compact tech note that translates ratios into rig settings and socket expectations. Mark attachment points for weapons and VFX anchors with coordinates relative to the pelvis or spine so that socket placement survives scale changes. Include simplified collision silhouettes for capes, skirts, tails, or wings, each labeled with intended simulation ranges. If LOD policy will reduce limb thickness or remove small accessories, specify a “proportion diet” that describes how much mass can be trimmed before reads degrade. Production should be able to build orthos, run a 3D block‑in, and test a walk cycle without sending you a single clarification email.

Avoiding Common Proportion Pitfalls

Three traps undermine proportion passes. The first is micro‑tweaking: moving everything by 5–10% so that variants feel safe but read the same at distance. The cure is discipline—commit to bolder 30% moves on a small set of levers and evaluate at gameplay scale. The second is compensatory noise: adding detail to make a weak proportion feel interesting. The cure is to downscale and squint; if the silhouette does not change, the noise is lying. The third is rig denial: inventing a charismatic body that the skeleton cannot support. The cure is to bind early in proxy 3D or to overpaint a rig proxy into your lineup so joint ranges stay real.

A Shared Definition of Done

For concept exploration, “done” means you have at least two A/B/C families with clear 30% deltas on defined levers, validated at multiple camera distances, and annotated with intent. For production, “done” means the hero proportion is locked with numeric ratios, socket plans, and collision outlines, and that it maps cleanly to an approved skeleton family. For the project, “done” means proportion logic is robust across skins, armor tiers, and marketing framing, and survives LOD policy without compromising class read. When everyone uses the same proportion package, iteration accelerates and rework collapses because the conversation shifts from taste to evidence.

Working Equally for Concept and Production

Concept‑side artists should embrace proportion passes as creative constraints that unlock surprising solutions; pushing head‑to‑body and limb rhythms by 30% often reveals new archetypes without redesigning mechanics. Production‑side artists should treat the passes as predictive tools; the earlier you test sockets, deformation, and cloth volumes against the proposed ratios, the cheaper every decision becomes. A shared A/B/C vocabulary lets both groups speak in numbers instead of adjectives, and it turns approvals into a transparent, testable process that scales across the entire character roster.

Proportion passes and A/B/C sets are not about indecision; they are about disciplined discovery. When 30% deltas are applied with intent, they surface the strongest grammar for a character’s role, and they keep that grammar intact from the first sketch to the shipped frame.