Chapter 3: Orthos / Turnarounds, Exploded Views & Callout Sheets

Created by Sarah Choi (prompt writer using ChatGPT)

Orthos, Turnarounds, Exploded Views & Callout Sheets — From Brief to Package (Prop Concept Pipeline)

Orthographic drawings, turnarounds, exploded views, and callout sheets are the handshake between concept and production. They’re where taste becomes math, where “cool” becomes measurable—and where animation, modeling, rigging, VFX, lighting, and QA find the same source of truth. This article lays out a practical, end‑to‑end approach that ties these documents to the pipeline: Ideation → Iteration → Finals → Handoff. It is written equally for concept artists preparing deliverables and production artists consuming them.

1) Why These Artifacts Exist

Silhouettes and mood boards sell direction; orthos and callouts keep it intact under pressure. Without them, teams guess: grips drift, sockets move, and “hero seams” vanish when topology gets tight. With them, ratios lock, pivots align, and every department can anticipate constraints. These documents are not just drawings—they are contracts describing shape, function, and behavior at the resolution needed to ship.

2) The Minimum Viable Set (Per Prop)

A robust handoff usually includes: (1) Orthographic views (front, side, top; rear if meaningful), (2) a 3/4 turnaround for curvature intent, (3) an exploded view with assembly order, (4) callout sheets covering dimensions, sockets, pivots, materials, and state changes, (5) a value map or grayscale to protect readability, and (6) an interaction bible (states, timings, FX windows). For multi‑state or puzzle props, add distinct ortho sets per state and a state delta sheet.

3) Units, Scale, and Datums

Pick a unit system (mm strongly recommended) and stick to it. Establish a primary datum (0,0,0) and note its position (typically center of grip or the gameplay attach point). Include a small scale bar on every sheet and the real‑world overall length/width/height. If your studio uses a standard pose datum for sockets (e.g., weapons oriented +X forward, +Z up), write it on the sheet header. Consistency here saves rigging and animation days.

4) Line, Value, and Layer Discipline

Use a three‑tier line system: outer silhouette (heaviest), primary mass breaks (medium), internal detail/engraving (light). Reserve section cuts for hidden geometry and draw them with a dashed convention. Keep all construction on separate layers: 00_GUIDES, 10_SILHOUETTE, 20_PRIMARY, 30_DETAIL, 40_CALLOUTS, 50_DIMENSIONS, 60_NOTES. Deliver layered source files; flattened exports are for reviews only.

5) Orthographic Best Practices

Orthos describe measurable truth. Keep them parallel‑projected, not perspective. Normalize the bounding box across views and align critical edges. Lock key ratios (overall aspect, body:signal area, void:mass) from earlier proportion passes, and print them on the sheet. Where curvature matters, add auxiliary views (e.g., grip cross‑section, nozzle profile). If a form blends between profiles (lofted surfaces), add stations—intermediate section curves at 10–20% intervals.

6) Turnarounds That Preserve Intent

A simple 4–8 frame turnaround (orthos + three‑quarter angles) communicates crown edges and taper intent better than words. Keep lighting flat; you’re describing form, not selling render. Show at least one view at the canonical gameplay angle. If a silhouette shifts significantly when posed (deploy/fold states), include a mini‑turnaround for each state. Use the same pivot annotations you’ll give rigging so the turnaround doubles as an animation hint.

7) Exploded Views: Show How, Not Just What

Exploded views demonstrate assembly logic. Order parts along realistic paths of dis/assembly (rails, hinges, screws) rather than radial fireworks. Use balloons with item numbers and provide a light bill of materials (BOM) keyed to materials and functional categories (frame, fasteners, optics, power, seals). Indicate fastener types (Torx T10, M4x0.7) only when relevant to storytelling or repeatability. Call out gaskets, shims, and clearances; these are where plausibility lives.

8) Callout Sheets: What Each Discipline Needs

  • Modeling: Max thicknesses, fillet radii ranges, segment counts where silhouette would suffer, target poly ranges per LOD, allowable bevel swaps.
  • Rigging/Animation: Pivot positions and axes, rotation limits, sliders’ travel distances, detents/click stops, timing beats (open 0.35s, lock 0.1s), collision volumes, stretch‑free zones.
  • VFX: Emissive mask IDs, intensity ranges, pulse curves, spawn sockets with naming, particle safe zones, occlusion expectations.
  • Lighting: Material roughness ranges, anisotropy direction arrows, intended spec highlights, decals that must catch key light.
  • Audio/Haptics: Impact materials by zone, expected resonance (hollow vs. damped), contact pairs for foley (metal/ceramic/leather), moments of emphasis.
  • Design/UI: Readability features (signal color regions), state feedback (LED count, seam continuity logic), accessibility notes (color‑blind alternatives).

9) Dimensioning That Communicates

Dimension for decisions, not for clutter. Use overall dims (L/W/H), then functional dims (grip length/circumference, socket diameters, clearance gaps). Mark tolerances where it matters (e.g., “slot width 12.0 ±0.5 mm”). Use fit classes informally: sliding fit, press fit, loose clearance. Avoid over‑specifying ornamental details; give ranges instead (“engraving depth 0.4–0.8 mm”). Dimension to datums, not to edges that may change.

10) Sockets, Datums, and Naming Conventions

Name sockets and pivots predictably: SCKT_MUZZLE_A, PIV_LATCH_A, LOC_CoM. Provide a socket map with coordinates from world datum and intended facing vectors. Include dummy locators in your blockout file so downstream teams can align attachments without guesswork. If your prop will host variants, mark reserved real estate where no geometry can intrude (e.g., scope rail volumes).

11) States and Transformations

For multi‑state or puzzle props, treat each state as its own truth. Provide orthos for stowed, ready, active, and any failure/service state. Add a state delta sheet that overlays differences in another color and lists changed dims, exposed sockets, and enabled/disabled motion channels. This reduces animation ambiguity and gives QA a test source.

12) Value and Material Maps (Readability Insurance)

Attach a grayscale value map to protect the read across LODs and lighting. Then add a simple material ID map (body, frame, signal, glass, fabric, rubber) keyed to your studio’s shader library. Specify parameter ranges rather than absolutes (roughness 0.35–0.55; emissive base 1.5–3.0). This empowers lighting and VFX to scale spectacle without changing identity.

13) Accessibility and Localization

If your callouts include text, ensure numerals and icons survive localization. Use icon‑based legends where possible, and call out non‑color redundancies (shape, blink patterns) for status feedback. Provide a color‑blind safe alternative palette for signal lights when feasible. Good accessibility notes reduce UI rework and improve QA pass rates.

14) Review Gates and Checklists

  • Ideation Gate: Do orthos reflect the chosen proportion ratios? Are sockets defined conceptually?
  • Iteration Gate: Are pivots, clearances, and motion limits specified? Is the exploded assembly plausible?
  • Finals Gate: Are dimensions, tolerances, and material IDs complete? Does the value map align with readability goals?
  • Handoff Gate: Are files layered and named correctly? Are blockouts with locators included? Is the interaction bible attached?

Use the same checklist every time so quality is predictable across artists and props.

15) File Hygiene and Hand‑Off Package

Adopt a simple naming scheme: PRP_<Family>_<Name>_<State>_<View>_v###. Include: layered PSD/AI/Krita, exported PNG/PDFs, a low‑poly blockout FBX/OBJ with locators, and a README outlining never‑break rules (ratios, socket positions, LOD survival cues). Compress as a versioned archive. If your studio uses DCC scene units, confirm that the blockout scale matches your sheet units.

16) Common Pitfalls (and Fixes)

  • Perspective creep in orthos → Toggle a grid, trace over with true orthographic alignment.
  • Over‑callout clutter → Prioritize decision‑making dimensions; move trivia to a secondary sheet.
  • Missing depths/thicknesses → Add section cuts for thin shells and laminated parts.
  • Floating pivots → Always dimension pivots from datums; include axis arrows.
  • Unreadable exploded views → Sequence along real guides and add tiny ghost rails to show paths.
  • Value drift between concept and model → Ship a value map and reference a grayscale render target in reviews.

17) Collaboration: Concept ↔ Production Loop

Concept artists: invite production to a 15–30 minute callout review before you finalize. Production artists: return a quick sanity blockout with notes (clearance fails, pivot conflicts, socket overcrowding). Capture agreements on the sheet, not just in chat. Tight loops here prevent rework later.

18) Applying This to Families and Variants

When a prop has trims or legendary skins, clone the base orthos and change only what the variant actually changes. Keep datum, sockets, and key ratios constant unless deliberately revising. Provide a delta callout inset showing differences: new materials, added ornaments, altered travel limits. This makes variants cheap and consistent.

19) A Practical Workflow You Can Repeat

  1. Lock proportions and ratios from earlier passes. 2) Establish units and datum. 3) Draft clean orthos (front/side/top/rear if needed) with section cuts for thickness. 4) Add a short turnaround to declare curvature intent. 5) Build an exploded view with assembly order and BOM. 6) Author callout sheets per discipline (modeling, rigging, VFX, lighting, audio/UI). 7) Dimension what drives decisions; add tolerances where needed. 8) Attach value/material maps and socket/pivot coordinates. 9) Package layered sources + blockout + README. 10) Run the handoff checklist and archive.

20) Closing Thought

Orthos, turnarounds, exploded views, and callout sheets are boring in the best way—they remove mystery. When you make them disciplined and repeatable, creative energy can move where it belongs: on design decisions that change the game, not on recovering from miscommunication. Treat them as your prop’s constitution; everything downstream will run smoother, faster, and more faithfully to your intent.