Chapter 2: Illumination, Parallax & Occlusion Reads

Created by Sarah Choi (prompt writer using ChatGPT)

Illumination, Parallax & Occlusion Reads — Aiming Systems & Targeting

Aiming systems live or die by how light, geometry, and motion agree with the player’s expectations. Illumination defines what the eye can see, parallax defines how the reticle behaves when the eye moves, and occlusion defines what blocks or contaminates the sight picture. For concept artists, these are shape and material problems that inform silhouettes, hoods, coatings, and reticle grammar. For production artists, they are shader, camera, and state‑machine problems that determine exposure stability, reticle drift, vignette, and collision with props and level dressing. This article unifies both perspectives across irons, optics, lasers, and smart sights so your aim reads stay honest in clear sun, fog, smoke, snow, neon night, and everything between.

1) Three Pillars: Exposure, Stability, and Continuity

Exposure: the sight picture must remain legible across bright floors, dark tunnels, muzzle flash, and volumetrics. Stability: the reticle must appear anchored to real geometry, not screen space, with predictable behavior when the eye or camera shifts. Continuity: as the player moves through states—ready, ADS, fire, recovery—the transitions should be smooth and interpretable, never surprising. These pillars lock trust: when they hold, players learn the weapon; when they fail, players fight the UI.

2) Illumination Fundamentals — Shaping Light Before FX

Good illumination starts with physical shapes. Sunshades, serrations, and micro‑baffles reduce veiling glare before shaders work. Hoods should cut high‑angle flare without boxing the view; their silhouettes should terrace rather than create single large planes that occlude. Interior finishes matter: bead‑blasted, low‑gloss blacks absorb stray light; fine concentric ribs on rings break reflections; anti‑reflective coatings add a subtle hue that telegraphs lens tech without cartoon glow. Place chamfers on sight edges to avoid aliasing sparkles under HDR bloom.

For night or dark interiors, use restrained emissives. Tritium dots and fiber rods should read as points, not lanterns. Reflex and holographic emitters need brightness rails that stop short of washing out the target. Concept sheets should show day/night strips with target plates at different values; production should link emitter intensity to auto‑exposure but ramp changes over ~250 ms to avoid flicker.

3) Parallax — What Moves When the Eye Moves

No sight is truly parallax‑free. The question is whether off‑axis eye positions cause believable, bounded drift. For reflex/holo optics, design a forgiving eyebox by slightly enlarging the window and reducing bezel occlusion; in production, clamp reticle drift within a small angular cone so a dot near the edge of the window never predicts wild POI errors. For irons, there is no reticle drift, but eye misalignment widens apparent post thickness and breaks equal daylight cues—your rear notch proportions should preserve daylight at mild head tilt.

Magnified optics add eye relief and exit pupil constraints. Concepts should signal this with ocular bell length and rubber guards; production should compute a soft vignette (“scope shadow”) driven by eye offset. Keep vignettes smooth and low‑contrast; over‑strong scope shadow becomes punitive and unreadable in motion. For smart sights, separate on‑glass overlays (follow optic) from world‑anchored HUD (follow camera) to avoid double motion during head bob or recoil.

4) Occlusion — What Blocks the Sight Picture

Occlusion splits into near‑field (your own kit), mid‑field (weapon and attachments), and far‑field (world clutter). Near‑field: slings, straps, and chest rigs should frame, not cover, the optic window. Route cables in recessed channels on both sides; carve shallow saddles for tape switches that keep windows 70–80% clear at ready, 90–100% at ADS. Mid‑field: keep top planes terraced; avoid stacking tall irons, risers, and gadgets into a wall. Far‑field: design reticles that maintain contrast on busy scenes—thickness and a faint outline beat neon color.

In production, author occlusion tests: sprint → aim at sun; crouch under ledges; shoot through chain link; stand near glass and smoke. QA should flag windows that vanish behind bloom or iridescent shader stacks. Add “high‑contrast reticle” and “reduced clutter” toggles that never change zero but improve read.

5) Irons — Light Discipline without Crutches

Irons rely on edges and proportion. Front posts should subtend ~6–12 MOA in common FOVs; rear notch width should leave daylight. Add anti‑glare serrations to top planes and micro‑beads to side faces. Provide a subtle undercut on the front face to reduce sky glare. Night dots should be sub‑dominant to the front post in daylight. For folding irons under optics, keep them low and slim—avoid ghost occlusion when folded by tucking them into recessed pockets.

Production: load irons as LOD‑aware meshes to prevent shimmer. Clamp post line thickness in pixels to avoid aliasing. Align bore/post with sub‑pixel precision in first‑person; in third‑person, exaggerate front sight height a touch so intent reads from distance.

6) Reflex & Holographic — Windows that Breathe

Windows must admit light without letting flare take over. Concept light traps in the hood: scalloped inner walls, absorbed ribs, and a narrow anti‑reflection film hue (blue‑green or purple) to telegraph AR coatings. Keep bezels thin; bevel interior edges. Reticles: dot (2–4 MOA), ring‑dot (20–65 MOA ring), or chevron. Offer a low‑brightness “sun mode” that increases core intensity, not halo size. Provide side battery trays with gasket reads to imply serviceability.

Production: simulate mild internal reflection only at steep angles; avoid mirror‑box looks that confuse depth. Implement brightness rails tied to exposure metering; clamp adjustment speed. Parallax drift should be bounded; dot should never fully detach from the physical window. Add a gentle, camera‑space stabilizer during ADS to reduce micro jitter without feeling screen‑space.

7) Magnified Optics — Relief, Tunneling, and Mirage

Eye relief is a promise the stock must keep. Concepts should include cheek risers and comb profiles that land the eye correctly. Add knurled magnification and diopter rings with throw levers that won’t snag slings. Reticles should scale with subtension correct across zoom; use SDF atlases for crisp lines. Avoid heavy “tunnel” vignettes; keep peripheral dimming modest and smooth.

Heat and mirage: depict mirage above suppressors and barrels with a subtle, localized heat‑haze that distorts the world but not the reticle; in scopes, this reads as reality bending, while the etched reticle stays rigid—an important trust cue. Don’t overdo; a small index‑of‑refraction pass near the muzzle sells heat without hiding targets.

8) Lasers & Illuminators — Scatter, Bloom, and Ethics

Lasers are aim intent under real air. In fog, rain, or dust, beams bloom; design lens shutters and power rails so “training” or “safe” modes use lower output and narrower divergence. Mount lasers near bore or with a consistent lateral offset; include a converged zero distance. Concept visible scatter only at proximity and in volumetric‑heavy scenes; production should cap beam brightness and length to prevent lightsaber reads.

Illuminators for NV require careful wavelengths and spill control. Use cooler emissives for IR logic and obvious lens caps or shutters for safe states. Provide a HUD hint for parallax at extreme close range, or a mild world decal showing converged point at the zero distance.

9) Smart Sights — AR on Glass without Lies

Smart sights mix on‑glass cues (range pips, drop ladders) with world HUD (threat boxes, waypoints). Keep on‑glass overlays subtle and parallax‑coupled to the optic; world annotations should be motion‑filtered and LOS‑aware. Concept failure modes: rain on lens, mud smear, battery low. Provide a graceful degrade to an etched center mark. Ethics: limit wall‑hack strength; if targets are highlighted, telegraph to opponents with visible sensor emissions, lens iris animations, or chassis lights.

Production: use tone‑mapped emissives that respect exposure; add adaptive outlines for high‑contrast mode; clamp angular velocity of HUD proxies to reduce nausea. Keep latency between sensor sample and UI update consistent; inconsistent lag breaks trust.

10) Weather & Environment — Sun, Smoke, Snow, Neon

Sun: Hood and shade first, then shader clamps. Add a small reticle outline on high‑albedo floors. Lens flares should be directional and never center‑screen over reticles.

Smoke/Fog: Reduce reticle halo, increase core intensity slightly. For lasers, widen scatter only a little; beams should attenuate quickly. Irons gain value via darker posts.

Snow/Ice: Auto‑invert a faint reticle outline on bright backgrounds. Add hydrophobic droplet normals that subtly distort the world but never shift the reticle.

Neon Night: Tone‑map emissives to avoid overbloom; use anti‑reflective finishes inside hoods. Keep HUD subdued so diegetic sights lead.

11) Camera & Animation — Selling Stability

Camera motion sets the stage for parallax reads. ADS should settle the optic window into a consistent on‑screen region (20–35% width). Recoil animation should rock the sight with a sharp impulse and a taught return; reticle reactions should follow within 10–30 ms so the eye reads cause → effect. For scopes, couple a small perspective zoom during ADS to simulate eye relief without harsh tunnel effects. For reflex, add a micro‑shake damped by the sling brace; too much noise kills acquisition.

12) Accessibility — High‑Contrast without Style Drift

Offer toggles for high‑contrast reticle outlines, reduced bloom, reduced camera shake, and thicker ground decals for smart‑sight footprints. Ensure color isn’t the only carrier of meaning; pair shape and timing patterns (dot + ring, chevron + tick). Keep all accessibility modes within the same value rails so cosmetics don’t become invisibility cloaks.

13) Production Handoff — What to Package

Concept: orthos of optic housings with hood depth, baffle profiles, and AR‑coating hue; day/night sight picture strips; parallax diagrams (eye positions vs reticle drift cones); occlusion thumbnails with sling/cable routing; failure modes.

Assets: separate lens meshes with correct normals, interior emissive planes, reticle SDF atlas, mask IDs for fingerprints/smudges; sockets for lasers/lights; folding irons with hinge logic.

Shaders: brightness rails tied to auto‑exposure, outline toggles, parallax clamps, scope vignette curves, heat‑haze refractive volumes.

Animation: state machine timings (raise → ADS → fire → recover), recoil impulse curves, reticle stabilization constants, sling tension cues.

QA: legibility under bright floors/dark caves, parallax drift bounds, occlusion edge cases (chain link, foliage), weather passes, color‑vision checks.

14) Case Studies — Bringing It Together

Urban Reflex: Thin‑bezel holo with scalloped hood, blue‑green AR cast. 3 MOA dot with 40 MOA ring; bounded parallax; brightness auto‑ramps; micro outline toggle. Sling routing keeps window 90% clear. In smoke, dot core brightens, halo clamps.

LPVO Patrol: 1–6× scope with modest, smooth vignette at eye offset. Reticle authored as SDF; etched ladder with illuminated center. Mirage near suppressor is localized; reticle stays rigid. Diopter and mag rings have glove‑friendly throw levers.

Smart Net Sight: On‑glass shows net canopy diameter; world decal previews footprint respecting slope. Battery low flips to etched center. Opponents see a faint lens iris when the rangefinder pings, preserving fairness.

Design the way light meets glass, how the dot behaves when the head moves, and how nothing gets between eye and target at the wrong moment. When illumination control, parallax bounds, and occlusion discipline agree, aim becomes instinct—and your weapons feel inevitable.