Chapter 3: Orthos, Cutaways & Callout Sheets

Created by Sarah Choi (prompt writer using ChatGPT)

Orthos, Cutaways & Callout Sheets

From Brief to Package: The Vehicle Concept Pipeline

Orthographic views, cutaways, and callout sheets are the documents that turn a promising vehicle concept into a buildable package. They translate the story of silhouette and gesture into coordinates, clearances, and interfaces so downstream artists, engineers, and vendors can act without guesswork. This article walks through how to plan, draw, and hand off orthos and cutaways, and how to construct callout sheets that survive production reality. The guidance is written equally for concept‑side artists who need to communicate intent quickly and production‑side artists who must surface, rig, fabricate, and maintain.

1) Where these artifacts sit in the pipeline

During Ideation, orthos and cutaways appear as loose scaffolds that pressure‑test proportion and feasibility. The objective is to remove ambiguity from the big moves: wheelbase and track, fuselage length and fineness, landing gear or suspension envelopes, hatch swings, turret arcs, radiator or thruster cross‑sections, and crew reach. During Iteration, orthos become the truth source for evolving hardpoints while cutaways validate internal routing, mass placement, and service access. By Finals, the set locks: clean front, side, rear, plan, and at least one section; optionally an exploded view for layered assemblies. At Handoff, callout sheets bundle dimensions, tolerances, materials intention, and interface notes so every downstream discipline inherits the same map.

2) Orthos: purpose, projection, and presentation

Orthographic drawings remove perspective to make measurement possible. Choose a projection standard early and label it clearly; most games and film concept teams default to third‑angle projection, but some vendors work in first‑angle. What matters is consistency and a prominent symbol or note so nobody inverts views. Set a real scale and stick with it across the set. A scale bar printed on the sheet saves teams when files get rescaled. Maintain the same ground line, ride height, and centerline across views so dimension chains align. If the vehicle articulates, provide a neutral pose orthos sheet plus a separate pose sheet for extremes of motion so the neutral truth remains clean.

Line discipline carries meaning in orthos. Reserve the heaviest weights for outer silhouette and cut boundaries, medium for primary part breaks, and light for secondary detailing. Use dashed lines sparingly for hidden edges; if too many appear, consider a cutaway instead. Keep all text and numerals vector‑clean and legible at print sizes; annotate using sentence‑case labels that read like tooltips rather than cryptic abbreviations. Indicate datum references—ground plane, vehicle centerline, and at least one mounting plane—so dimensions can be chained instead of floating.

3) What to dimension and what to describe with words

Dimension what governs behavior and interfaces, describe with words what governs aesthetics. Wheelbase, track, overall length and height, ground clearance, approach/departure/breakover angles, axle centerlines, suspension or gear bay envelopes, weapon recoil envelopes, sensor gimbal spheres, hatch apertures, hinge offsets, and canopy swing arcs are numerical truth and belong in dimensions. Surfacing intent—soft versus tight radii, panel crown direction, and character line hierarchy—belongs in brief notes and shaded thumbnails placed near the orthos. This separation keeps the blueprint legible while preserving design intent.

4) Views to include and when to add more

At minimum, include side, front, rear, and plan. For asymmetrical vehicles or complex rooflines, add a second plan or a bottom view. Mechs and walkers usually need both leg‑neutral and stride‑neutral orthos to resolve leg geometry; helicopters and tiltrotors need plan and front views at a minimum because rotor diameter and disk clearance dominate composition. Spacecraft benefit from a simple isometric wireframe alongside the orthos to prevent misread of stacked volumes. If a single view is carrying too much hidden geometry, schedule a section or cutaway rather than piling on dashed lines.

5) Cutaways: choosing the right section and telling a clean story

A cutaway should answer a precise question. If the problem is crew packaging, slice through seat H‑points and control paths. If the problem is thermal management, section through intake, heat exchangers, and exhaust. If the problem is structural, cut through spars, frames, and load paths. Choose the plane that removes the most occlusion with the fewest distracting reveals and avoid diagonal slices unless they dramatically simplify reading. Use a single hatch style for structural members, a second for tanks and batteries, and a flat tint for air or void. Keep parts behind the section plane faint, and silhouette the cut edge with a strong weight so the viewer never confuses cut material with background objects.

Cutaways thrive on hierarchy. Start with major masses: crew, power, payload. Place routing next: cooling ducts, wiring harness corridors, fuel or power busses, and recoil or gimbal volumes. Add service logic: fastener access, filter or magazine swaps, and panel removal paths. Only then sprinkle secondary details. If the scene becomes visually busy, duplicate the cutaway and gray out everything except the subsystem you are explaining—one plate per story keeps cognition low.

6) Exploded views and assembly logic

Exploded views are cousins of cutaways that show order of operations rather than interior content. Use them when the handoff requires assembly steps or to prove that a panelization strategy exists. Keep the explode axes orthogonal to the main datum so parts fly apart cleanly. Place small arrows and sequence numerals to imply order, and add minimal callouts for hardware families when relevant. Reserve these plates for Finals and Handoff when part definitions have stabilized; early in Iteration a simpler cutaway is usually more honest.

7) Callout sheets: from caption soup to actionable guidance

A callout sheet anchors the intent of the concept and points to the interfaces that matter. It is not a dumping ground for every thought. Start with a one‑paragraph “design sentence” that states role, performance priorities, and signature reads. Follow with labeled plates—orthos, cutaway, or exploded—where each arrow points to something an adjacent team must know. For concept artists, call out surfacing hierarchy, livery zones, lighting signature, and hero breaks that should survive optimization. For production artists, call out hinge types and swing angles, minimum fillet radii, seam strategies, gasket or boot placements, and keep‑out volumes around exhausts, intakes, sensors, weapons, or landing gear.

Use consistent numbering and a mini legend. If a label appears in multiple plates, keep the same number so continuity survives across files. When naming parts, prefer function‑forward terms—“upper control arm,” “aft radiator deck,” “port ISR gimbal,” “starboard service hatch”—over stylistic nicknames. If the vehicle family has variants, note which callouts are universal and which are trim‑specific so the sheet becomes a reusable template.

8) Integrating orthos and cutaways across Ideation → Iteration → Finals → Handoff

In Ideation, draw light orthos over your proportion passes with the simplest rectangles, circles, and arcs that can hold hardpoints. Drop human figures and equipment proxies for truth. If anything looks implausible, make a fast cutaway to see where volume is missing. In Iteration, tighten to a single scale and begin dimensioning the unambiguous facts. Create one authoritative section—usually through the cabin—to settle seating, sightlines, and controls. Start a callout sheet but keep it to big rocks only so pivots stay cheap.

By Finals, freeze the governing dimensions and present immaculate linework. Replace proxy geometry with believable part breaks and simple fastener logic, but resist the urge to over‑detail; clarity beats complexity. Ensure there is one definitive cutaway that tells the system story you are most likely to be questioned on—thermal, structural, or service. At Handoff, consolidate into a package: a master orthos plate, the hero cutaway, any essential exploded views, and a callout sheet with a brief bill of materials for key subassemblies. Include a short “known unknowns” paragraph so downstream teams aren’t surprised by intentional gaps.

9) Readability, scale, and print discipline

Designs live on screens and in print. Set your type once, test at 100% print size, and refuse to shrink below a legible point size for your studio. Keep a generous margin around the perimeter; reviewers need space for notes. Place a scale bar, projection symbol, and unit declaration on every plate. Pick a unit system—metric or imperial—and stick to it per project. If your stakeholders mix systems, include both but keep one primary. Preface fractions with zeroes to avoid misreads and align decimal places in stacked dimensions to aid scanning.

10) Common failure modes and the fixes that preserve intent

Ambiguous datums cause dimension chaos; solve it by declaring ground, centerline, and at least one reference plane on every plate. Hidden‑edge overload makes drawings hard to read; fix by choosing a cutaway instead of more dashes. Over‑detailing early plates creates false certainty; keep Ideation and early Iteration orthos intentionally sparse so pivots are cheap. Beautiful but unbuildable seams waste time; pair any complex seam with an exploded detail that shows fastening and gasket logic. Callouts that read like prose essays go unread; convert them to crisp sentences tied to numbers and arrows.

11) Collaboration rituals between concept and production

Healthy pipelines share ownership. Establish a review rhythm where concept owns silhouette and signature reads while production owns build logic and service health. Run short “arm‑wrestle” sessions in Iteration where a single seam or hinge is debated with quick overlays. When production identifies a fabrication constraint—minimum bend radius, tool access, or draft requirements—invite it onto the plate as a ghosted template rather than as off‑sheet tribal knowledge. Conversely, when concept needs a hero line to survive, encapsulate it as a protected spline with a label that says so.

12) Mini case study: tiltrotor troop carrier

The brief calls for a compact tiltrotor that fits in urban landing zones and carries eight troops. Early orthos lock rotor diameter, wing span, and fuselage height to meet clearance and downwash limits. A plan cutaway through the wing root shows gearboxes, fold joints, and fuel routing, revealing that the first canopy idea collides with a lift fan duct. Iteration shifts the canopy forward by a small amount and adds a periscope sight to recover visibility. Finals present immaculate orthos with rotor disk envelopes and neutral pose gear geometry. The hero cutaway slices through the cabin to show troop bench spacing, weapon stowage, and egress steps. The callout sheet anchors hinge styles, fold sequence, and service panels that can be removed with a basic tool kit in under five minutes. Handoff bundles these plates with a risk note on gearbox cooling that the systems team will validate in simulation.

13) File hygiene and version safety

Name files so their purpose is obvious and so chronological order tells the story: project_vehicle_viewtype_version_date. Embed a small metadata block on each plate recording the dimension source, the projection standard, and which team approved the last change. Keep a separate “graveyard” page for retired solutions so the main plates stay clean while decisions remain auditable. Archive authoritative PNGs or PDFs alongside layered source files so non‑artists can read them without software friction.

14) Closing thoughts

Orthos, cutaways, and callout sheets are not bureaucratic hurdles; they are storytelling at the level where other people must act. When you connect them thoughtfully to the Ideation → Iteration → Finals → Handoff rhythm, you create a shared truth that lets concept explore boldly and production build confidently. The result is a vehicle that reads at a glance, assembles without drama, and can be serviced by people who were never in the room when the sketch was made. That is the quiet power of drawing clearly.