Chapter 1: Stress Maps

Created by Sarah Choi (prompt writer using ChatGPT)

Stress Maps for Mecha: Edges, Steps, Handles (Wear, Weathering & Damage States)

A stress map is a prediction. It’s your best guess—based on physics, maintenance habits, and mission profile—about where a mecha will get touched, scraped, heated, corroded, and repaired. When wear and damage are placed by logic instead of randomness, the mecha feels heavy, used, and believable even in a clean render. For concept artists, stress maps are a shortcut to convincing storytelling: you can add the right scuffs in the right places and instantly sell scale and function. For production artists, stress maps are a pipeline plan: they tell you where to spend texture resolution, where to author bespoke masks, and how to build reusable material layers that look consistent across assets.

The key mindset is that wear is not decoration. Wear is a record of forces: contact, pressure, vibration, heat, water, chemicals, and time. Stress mapping turns those forces into predictable patterns—edges polish, steps abrade, handles gloss, hot zones discolor, and sheltered cavities collect grime.

Stress maps are different from “edge wear”

The common beginner move is to put chips along every edge and call it weathering. Real machines don’t wear evenly. They wear where humans or robots interact with them, where parts rub, where debris hits, where heat cycles, and where water sits. A stress map is selective. It’s a set of “hotspots” and “flow lines,” not a uniform filter.

For concepting, this means you don’t need to add more wear everywhere—you need to place wear in fewer, smarter areas. For production, it means you should avoid curvature-only generators as your main story. Curvature is a helpful tool, but it must be steered by authored masks that represent use.

Four drivers: contact, flow, heat, and chemistry

Most mecha wear can be explained by four drivers. Contact is anything that touches: boots on steps, hands on handles, tools on fasteners, armor rubbing armor at joints. Flow is anything that moves past: rain streaks, dust-laden wind, hydraulic mist, exhaust plume, coolant leaks. Heat is anything that cycles temperature: exhaust collars, weapon muzzles, radiators, thruster bells, friction brakes. Chemistry is anything that reacts: salt corrosion, acid rain, chemical exposure, galvanic corrosion between dissimilar metals.

Concept artists can pick two or three drivers to emphasize based on environment and role. A desert scout emphasizes dust flow and abrasion. A naval unit emphasizes salt chemistry and wet streaking. A siege unit emphasizes heat cycling and spall damage. Production artists can translate those drivers into layer stacks: abrasion layer, dirt layer, soot/heat layer, corrosion layer.

Building the stress map: start with interaction points

The quickest way to stress-map a mecha is to mark interaction points first. Where do crews climb? Where do they grip? Where do they open panels? Where do they place tools? Where do they attach cables, tow lines, or lift slings? These points create the most distinctive wear because they are repetitive and human-scale.

Edges near steps and handholds polish and scuff because boots and gloves abrade them. Handles become glossier from oils and repeated contact. Access panel corners get chipped from prying and tool slips. Safety rails and ladder rungs show paint rub at contact zones.

For production, these interaction points are where you want bespoke detail: higher texel density, unique wear masks, and decals for warnings. In a game, these are also the areas players look at up close—cockpit entry, weapon swaps, repair animations—so the return on investment is high.

Edges and corners: impact logic, not “outline chips”

Edges wear in specific ways. Leading edges that face motion or debris (shins, forearms, shoulder fronts) get peppered with micro impacts, chipped paint, and directional scuffing. Trailing edges stay cleaner. Corners at access points get localized damage: small chips, primer reveal, and grime tucked into the seam.

For concept artists, think in “vector wear.” Where does the mecha move through the world? Where does it push past cover? Where does it kneel or brace? Put the most impact wear on those vectors. For production, build directional wear masks: use world-space gradients and authored splats aligned to travel direction, not just curvature.

Steps, walkways, and anti-slip zones

Steps and walkable surfaces are wear machines. They collect dust, show scratches, and lose paint quickly, but they also often have protective treatments: textured anti-slip coatings, grit tape, or knurled metal. Those treatments change the wear signature—anti-slip gets clogged with dirt, edges polish where boots compress the texture, and the coating can peel in patches rather than chip like paint.

Concept artists can use walkways to sell scale immediately. A single stair tread with scuffed paint and dirt-packed texture tells the viewer, “Humans use this.” Production artists should treat walkways as their own material set: rougher baseline, granular normal, dirt retention in cavities, and clear edge transitions where the coating stops.

Handles, grips, and touch zones: the “gloss halo”

Touch zones often become smoother and slightly glossier over time because oils and abrasion polish the micro-surface. This is one of the most believable and underused cues in PBR. A matte-painted panel can stay matte, while the handle on it becomes subtly satin from use.

For concepting, you can indicate this with a small highlight accent and a darkened grime edge where fingers don’t reach. For production, implement touch zones primarily in roughness: a slight reduction in roughness (smoother surface), plus localized smudge masks. Keep it subtle—if the handle becomes mirror-gloss, it looks like chrome rather than worn paint or rubber.

Heat stress: discoloration, soot, and material transitions

Heat does more than add soot. Repeated heating and cooling can discolor paint, change roughness, crack coatings, and bake grime into a hard sheen. Exhaust and weapon zones often show gradients: darker near the source, then a broader halo where heat cycles. If the mecha uses ceramic coatings or heat shields, those areas can look chalkier and more stable, while adjacent metal shows heat tint and oxidation.

Concept artists can map heat stress by tracing flow paths: where does exhaust wash? where does muzzle blast vent? where do radiator plumes go? Then place soot and discoloration along those paths, not symmetrically. Production artists can build heat layers that modify both color and roughness and can be driven by gameplay states (freshly fired vs cooled down). A good heat layer is mid-frequency and survives distance better than tiny scorch specks.

Corrosion: water retention and material pairing

Corrosion is mostly about water retention and chemistry. Water sits in seams, under gaskets, behind brackets, and at the bottoms of cavities. Salt accelerates it. Dissimilar metals can create galvanic corrosion at fasteners and joints. Paint failure often starts at chips and seam edges, then blooms outward.

For concept artists, you don’t need full rust everywhere to sell corrosion. A few smart placements—seam bottoms, fastener halos, drain paths, and chipped leading edges—do more than a uniform orange overlay. For production, corrosion is a layered effect: start with paint chip masks, add localized oxidation around chips and fasteners, then add streaking below those points. Control saturation and value so corrosion doesn’t overpower the base design.

Scuffs and scratches: scale, direction, and density

Scuffs come from broad contact: brushing against walls, dragging cables, sliding armor plates. Scratches come from sharper contact: tool slips, shrapnel, debris. The most important rule is scale. Small scratches should be tiny relative to the mecha; if they’re too big, the mech reads as a miniature model. The second rule is direction. Scuffs and scratches often have consistent orientation based on movement and contact.

Concept artists can suggest this with a few directional streaks near high-contact areas, avoiding “random noise.” Production artists can use anisotropic-like scratch normals sparingly, with direction aligned to surface function (e.g., longitudinal scuffs on shin guards, circular wear around rotating couplings). Use roughness to carry the read; normal-only scratches often disappear at distance.

Damage states: from clean → used → broken (and back again)

Stress maps become even more powerful when you think in damage states. A pristine factory mech has crisp finishes and minimal grime. A deployed mech shows touch polish, dust accumulation, edge chips, and heat halos. A heavily damaged mech shows larger material failure: peeled coatings, exposed substrate, cracked ceramics, leaking fluids, and field repairs.

For concept artists, you can design these states as variations: A/B/C sets where each step increases wear logically rather than randomly. For production, damage states can be implemented with mask-driven layers: base wear always present, plus additional layers activated by gameplay condition or customization. Keep the signature landmarks consistent so the mech remains recognizable even when damaged.

Material-aware stress maps: metals, composites, ceramics, glass

Metals tend to dent, gouge, and show bright exposed substrate when coatings chip. Edges polish and can show bare metal at contact points. Corrosion may appear at seam bottoms and around fasteners, especially in wet/salty environments.

Composites don’t dent the same way; they can crack, delaminate, or fray at edges. Paint over composites chips to reveal a different underlayer, and impacts may show lighter fibers or resin. Fasteners often sit in metal inserts, so wear clusters around those hardpoints.

Ceramics resist scratching but can chip and spall. Thermal ceramics may show micro-cracking and soot staining without metal-like gouges. Tile systems show seam wear and replacement patterns rather than random scratches.

Glass shows micro-scratches, smudges, and edge chipping, but it also carries environmental storytelling through streaks and dust. The frame and gasket around glass often show the strongest wear because that’s where maintenance happens.

Production translation: masks, layers, and where to spend effort

A practical production approach is to author a stress map as a set of masks: interaction (handles/steps), impact (leading edges), heat (exhaust/weapons), moisture (seams/cavities), and repair (patch panels). These masks can be reused across LODs and even across similar assets.

Concept artists can help by delivering a simple “stress callout sheet” alongside the design: a paintover that marks the hotspots and explains why. Production artists can then build smart materials that respond to those masks: paint chips that reveal primer and metal, soot that increases roughness and darkens albedo, corrosion that blooms from chips, and touch polish that smooths roughness.

Closing: stress maps make wear believable and controllable

The difference between “cool weathering” and believable wear is intention. Stress mapping gives you that intention by tying scuffs, chips, heat, and corrosion to forces and habits. For concept artists, it’s a design tool that sells scale and function with minimal marks. For production artists, it’s an authoring plan that keeps wear consistent, performant, and adjustable across damage states. When you build stress maps into the design from the start, the mecha’s surface becomes a readable history of how it lives in the world.