Chapter 4: Intake / Exhaust Placement & Silhouette Effect

Created by Sarah Choi (prompt writer using ChatGPT)

Intake / Exhaust Placement & Silhouette Effect — Designing Airflow That Reads

If fins and radiators are the texture of thermal design, intake and exhaust placement is the architecture. Where a mecha breathes—where it pulls in cool air and where it pushes out hot air—affects everything: believability, silhouette, faction identity, gameplay readability, and production feasibility. A mech with intentional intake/exhaust placement feels like a working system. A mech with random vents feels like a costume.

This article is written equally for mecha concept artists on the concepting side and the production side. For concepting, the goal is to design airflow as a clear visual story that strengthens silhouette and avoids “vent spam.” For production, the goal is to place vents where they can be built, rigged, and VFX’d: with plausible volume behind them, consistent directionality, and scalability across LODs, skins, and damage states.

Thermal language rests on three pillars: heat generation, airflow, and heat rejection. Intake and exhaust placement sits in the middle pillar. It is the path that connects heat sources to heat rejection.

Why intake/exhaust placement is a silhouette tool

Intakes and exhausts are not subtle. They change a silhouette because they need openings, recesses, louvers, and protected cavities. They also create strong visual “mouths,” “gills,” “nostrils,” and “chimneys,” which audiences read emotionally.

A forward-facing intake can make a mech feel predatory or aerodynamic. A dorsal exhaust stack can make it feel industrial and powerful. Side gills can make it feel aquatic or biomechanical. Vent clusters near joints can make it feel like a high-performance robot.

If you treat airflow as a silhouette motif, you get free readability: viewers can tell where the power lives and how the unit is meant to operate.

Start with a heat map: where does the hot air come from?

Placement begins with heat sources. Before you decide where vents go, decide what must be cooled.

Major heat sources typically include power cores/engines, electric motors and gear reduction at major joints, pumps and fluid systems, weapon systems, and high-density electronics. Once you know where heat is generated, you can decide where it should leave.

For concepting-side artists, a quick “heat map overlay” is enough: hot zones in torso/back, moderate zones at hips/shoulders, smaller hot zones at wrists/ankles or weapon mounts.

For production-side artists, this map prevents vents from being scattered arbitrarily and helps teams coordinate emissive, heat haze, soot, and damage.

Intake logic: clean air, protected paths, and filtration cues

Intakes want cooler air and cleaner flow. They also want protection from debris, water, and impact.

Visually, intakes read as recessed openings with grills, meshes, or honeycomb. They often look “cleaner” than exhausts: less soot, less staining, more filtration cues.

Placement-wise, intakes often sit on forward or lateral surfaces where the mech can access ambient air. But they should avoid areas that are likely to ingest the mech’s own exhaust. If you place an intake too close to an exhaust outlet, the design implies recirculation, which reads inefficient unless it’s a deliberate worldbuilding choice.

A good depiction trick is to give intakes “lip protection”: a recessed cavity, a rim, or a louver that blocks direct line-of-sight to internals. This makes the opening feel designed rather than like a hole punched in armor.

Exhaust logic: hot air wants a direction and consequences

Exhausts want to move hot air away from sensitive parts and away from humans. They also create surface consequences: heat staining, soot trails, and heat haze.

Visually, exhausts can be larger ducts, slit vents, louvered outlets, or nozzle-like ports. They often look harsher than intakes: sharper edges, heat shields, soot, and discoloration.

Placement-wise, exhausts often go rearward, upward, or away from limbs and crew areas. Downward exhausts can be used intentionally for ground effects (dust, debris clearing, braking jets), but they should look protected and purposeful.

A key silhouette rule is that exhausts should not point directly into the mech’s own structure. If an exhaust is near a wing, shoulder plate, or backpack, it should have a heat shield, deflector, or spacing that suggests protection.

The airflow story: design a few primary paths, not hundreds of vents

The most believable mechs have a small number of primary airflow paths.

A common pattern is “intake low/forward, exhaust high/rear.” Another is “intake side gills, exhaust dorsal stack.” Another is “intake chest, exhaust back.” You can invent your own, but commit.

You don’t need to show internal ducts. You do need to imply that air can travel. Recessed channels, vent corridors, and consistent vent orientation suggest flow without diagrams.

For concepting-side artists, choosing one airflow pattern early helps prevent vent spam. For production-side artists, it creates a consistent placement language that can be reused across variants.

Silhouette patterns: how placement changes the character read

Intake/exhaust placement creates recognizable silhouette archetypes.

A dorsal stack (exhaust on the back/top) makes the mech feel like a furnace or engine. It reads heavy, industrial, and powerful. It also naturally frames heat haze and plume VFX.

A thoracic chest intake makes the mech feel like it “breathes” like a creature. It reads heroic or predatory depending on shape.

Shoulder gills make the mech feel athletic and high-performance. They suggest strong upper-body motors and control systems.

Calf vents and ankle exhausts emphasize locomotion and sprint capability. They also create strong dust and heat haze hooks near the ground.

Hip vents often read as power routing hubs—good for heavy units.

Distributed micro-vents can read futuristic and efficient, but they risk becoming noise unless they are patterned and restrained.

Choosing one or two of these patterns and repeating them across the design gives the mech a coherent thermal identity.

Radiation and “line-of-sight heat”: why baffles and louvers matter

Thermal radiation is line-of-sight. That means placement isn’t just about airflow; it’s about what surfaces are exposed to a hot source.

If you have a very hot exhaust outlet or reactor seam, nearby surfaces should look protected: heat shields, louvers, baffles, or standoff plates. These protections also strengthen silhouette and help separate forms.

In depiction, radiation management reads as layered surfaces: a vent outlet recessed behind louvers, a nozzle with a shroud, a hot seam facing outward rather than inward.

For production, these layers become clear part separation and provide places for emissive, soot, and heat discoloration without contaminating the whole asset.

“Breathing” as animation: vents that change state

A mech feels alive when its thermal output changes with load.

You can design vents that “breathe” through state changes: louvers that open wider under load, vent panels that crack open in overheat mode, and exhaust clusters that pulse during boost.

In concepting, you can show this with small callouts: idle vs active vs overheat silhouettes. You don’t need full effects—just indicate which vents activate.

In production, these state-based vents become rigging and VFX requirements. Even if the vents don’t physically move in game, the concept can still inform emissive and particle states.

Environment interactions: dust, water, snow, and how placement adapts

Airflow doesn’t exist in a vacuum. Placement should respond to environment.

A desert mech benefits from intakes that are elevated, protected, and filtered. A snow mech benefits from intakes that avoid ingesting powder and from exhaust placement that prevents icing on critical surfaces. A coastal mech benefits from corrosion-aware placement and protected grills.

Depiction-wise, you can hint at this with intake filters, dust caps, water-shedding louvers, and guarded vent corridors.

For production, these cues help justify different skins or variants that adapt the same base model to different biomes.

Concepting-side workflow: plan airflow as a design motif

In early ideation, decide three things: your primary intake zones, your primary exhaust zones, and your thermal personality (runs hot and dramatic vs cool and controlled).

Then block in vents as big shape motifs first: cavities, stacks, gills, or dorsal ridges. Only after the silhouette reads should you add grill patterns and louver details.

A high-value deliverable is a simple airflow diagram overlay: a few arrows showing intake and exhaust direction. It communicates intent to production without extra rendering.

Also choose a limited set of vent pattern motifs and repeat them. Consistency is what makes airflow feel engineered.

Production-side workflow: buildability, clear volumes, and collision safety

For production, vents need believable volume. If you put a big intake on a thin plate, it reads hollow in a bad way. Reserve space behind vents by adding thickness, recess, or adjacent housings.

Consider collision and motion. Vents on moving parts must not collide with adjacent armor during extreme poses. Vents that open (even conceptually) should not be blocked.

Plan LOD. Fine grill detail will disappear, so the intake/exhaust silhouette must still read through cavity shapes and large openings.

Coordinate with VFX. Primary exhausts should have clear direction and a stable attachment point for heat haze and particles. Secondary vents should be subtle and not all spawn effects.

Align vent seams with part separation. A vent pattern that crosses multiple parts will cause UV and decal issues and will break visually when animated.

Common placement mistakes and fixes

A common mistake is placing vents everywhere. Fix it by selecting a primary airflow architecture and limiting vents to those zones.

Another mistake is putting intakes next to exhausts. Fix it by separating intake and exhaust faces or by adding baffles and deflectors that imply recirculation control.

Another mistake is vents with no cavity or thickness. Fix it by recessing the vent area, adding a duct lip, or increasing the local housing volume.

Another mistake is exhaust pointing into the mech. Fix it with a directional outlet, a deflector plate, or relocating the exhaust.

Another mistake is ignoring radiation. Fix it by adding shields, louvers, or spacing near hot outlets.

A paragraph-form intake/exhaust pass before you finalize

Before you finalize intake and exhaust placement, ask: do you have a heat map that explains why these vents exist? Is there a clear airflow story with a few primary paths rather than many random openings? Are intakes protected, filtered, and placed on cooler faces, while exhausts are directional, heat-stained, and placed to avoid cooking the mech itself? Do your vents create a coherent silhouette motif that matches role and faction culture? And will these vent shapes survive production realities like LOD, rig clearance, UV seams, and VFX budgets?

If the answer is yes, your thermal language will read as a designed breathing system.

Closing: where a mech breathes is who a mech is

Intake and exhaust placement is one of the most identity-defining choices you make in mecha design. It turns “cool vent shapes” into a believable thermal architecture, strengthens silhouette, and creates actionable hook points for production. For concepting-side artists, it’s a powerful motif that ties function to style. For production-side artists, it’s a buildable map of cavities, seams, and effect zones that can be implemented consistently.

When you design airflow intentionally, your mecha stops looking like it has vents—and starts looking like it breathes.