2nd/10_Wiki/Topic_Programming/Programming & Language/시각-전정 충돌(Visual-vestibular conflict).md

id, title, category, status, canonical_id, aliases, duplicate_of, source_trust_level, confidence_score, verification_status, tags, raw_sources, last_reinforced, github_commit, tech_stack

id	title	category	status	canonical_id	aliases	duplicate_of	source_trust_level	confidence_score	verification_status	tags	raw_sources	last_reinforced	github_commit	tech_stack
wiki-2026-0508-시각-전정-충돌-visual-vestibular-confl	시각-전정 충돌(Visual-vestibular conflict)	10_Wiki/Topics	verified	self	VVC visual-vestibular mismatch sensory conflict	none	A	0.95	applied	vr perception sickness vestibular		2026-05-10	pending	language framework any vr

시각-전정 충돌(Visual-vestibular conflict)

매 한 줄

"매 visual motion 과 vestibular system 의 input mismatch 가 sickness 를 유발한다". Reason & Brand 의 1975 sensory conflict theory — VR 에서 user 가 see motion but feel stationary (or vice versa) 시, 매 brain 이 conflict 를 poison signal 로 misinterpret. 매 modern VR 의 #1 design constraint.

매 핵심

매 메커니즘

• 시각 cue: optic flow 가 forward motion 을 indicate.
• 전정 cue: 머리 actual movement 가 zero (sitting still).
• Mismatch detection: vestibular nuclei 가 conflict 를 detect.
• Evolutionary response: poison hypothesis (Treisman 1977) — nausea, vomit reflex.

매 영향 요소

• FOV: wider FOV → 매 stronger optic flow → 매 worse VVC.
• Acceleration: linear acceleration > constant velocity.
• Yaw rotation: smooth turning 이 worst (snap turn 으로 mitigate).
• Latency: motion-to-photon > 20ms 시 sickness 가속.

매 응용 (mitigation)

1. Teleportation locomotion (no continuous motion).
2. Vignette / tunneling on movement.
3. Snap turn (e.g., 30° increments).
4. High refresh rate (90Hz+, 2026 standard 120Hz).
5. Cockpit / static reference frame.

💻 패턴

Vignette on locomotion (Three.js)

import * as THREE from "three";

const vignette = new THREE.ShaderMaterial({
  uniforms: { intensity: { value: 0 } },
  fragmentShader: `
    uniform float intensity;
    varying vec2 vUv;
    void main() {
      float d = distance(vUv, vec2(0.5));
      gl_FragColor = vec4(0., 0., 0., smoothstep(0.3, 0.7, d) * intensity);
    }`
});

function onLocomotion(speed: number) {
  vignette.uniforms.intensity.value = THREE.MathUtils.clamp(speed / 5, 0, 0.7);
}

Snap turn implementation

const SNAP_DEGREES = 30;
let lastSnap = 0;
function onThumbstickX(x: number) {
  const now = performance.now();
  if (Math.abs(x) > 0.7 && now - lastSnap > 250) {
    camera.rotation.y -= Math.sign(x) * THREE.MathUtils.degToRad(SNAP_DEGREES);
    lastSnap = now;
  }
}

Teleport locomotion

function teleport(target: THREE.Vector3) {
  fadeToBlack(100);
  setTimeout(() => {
    rig.position.copy(target);
    fadeFromBlack(100);
  }, 100);
}

Frame-rate enforcement

// 90Hz minimum on Quest 3, 120Hz on Vision Pro
const targetFPS = navigator.userAgent.includes("Vision") ? 120 : 90;
renderer.setAnimationLoop((t, frame) => {
  // skip work if budget exceeded
});

매 결정 기준

상황	Approach
Seated experience	continuous + vignette OK
Standing / room scale	teleport + snap turn 권장
Racing / cockpit sim	static cockpit ref → 매 reduces VVC
Audience first-time	always teleport default
Pro user	option for smooth

기본값: teleport + snap turn 30° + vignette on continuous motion.

🔗 Graph

• 부모: VR Sickness
• 변형: Vergence-Accommodation Conflicts
• Adjacent: 가상현실 멀미 (VR Sickness) · 안구 운동 기능 (Oculomotor Functions)
• 응용: 가상현실(VR) 자전거 시뮬레이터

🤖 LLM 활용

언제: locomotion 설계 review · sickness 원인 분석 · UX option 추천. 언제 X: actual user testing 의 substitute (subjective experience 측정 필수).

❌ 안티패턴

• Smooth locomotion default: 매 first-time user 의 30%+ 가 sick.
• No comfort options: accessibility 실패.
• Frame drop tolerance: 60Hz fallback → severe sickness.
• Forced rotation: cinematic 의도 → 즉시 sick.

🧪 검증 / 중복

• Verified (Reason & Brand 1975 · Stanney VR Handbook · Meta VR Comfort guidelines).
• 신뢰도 A.

🕓 Changelog

날짜	변경
2026-05-08	Phase 1
2026-05-10	Manual cleanup — VVC mechanism + mitigation 코드