2nd/10_Wiki/Topics/Programming & Language/가상현실 멀미 (VR Sickness).md

---
id: wiki-2026-0508-가상현실-멀미-vr-sickness
title: 가상현실 멀미 (VR Sickness)
category: 10_Wiki/Topics
status: verified
canonical_id: self
aliases: [VR Sickness, Cybersickness, Motion Sickness in VR]
duplicate_of: none
source_trust_level: A
confidence_score: 0.9
verification_status: applied
tags: [vr, ux, perception, motion-sickness, hmd]
raw_sources: []
last_reinforced: 2026-05-10
github_commit: pending
tech_stack:
  language: C#
  framework: Unity/Unreal
---

# 가상현실 멀미 (VR Sickness)

## 매 한 줄
> **"매 vestibular (전정) 와 visual (시각) input 의 mismatch 로 발생하는 nausea / disorientation"**. 매 motion sickness 의 inverse — 매 눈은 움직임을 보지만 몸은 정지. 매 90+ FPS, low-latency tracking, comfort locomotion 으로 완화. 매 Quest 3 / Vision Pro 시대에도 여전히 핵심 UX 문제.

## 매 핵심

### 매 원인 (sensory conflict theory)
- **Vection**: 매 visual self-motion 의 인지 (정지한 vestibular 와 conflict).
- **Latency**: motion-to-photon >20ms — 매 멀미 유발.
- **Frame rate dip**: 90Hz → 60Hz drop 의 즉시 swimming sensation.
- **Field of view + speed**: 매 wide FOV + fast translation = 매 worst.
- **Postural instability**: 매 head tracking error / drift.

### 매 완화 기법
- **High refresh rate**: 90/120Hz 표준 (Quest 3 = 120Hz, Vision Pro = 90/96Hz).
- **Low motion-to-photon latency**: <20ms target.
- **Vignette / Tunneling**: 매 turn / locomotion 시 peripheral 차단.
- **Teleport locomotion**: 매 smooth movement 의 회피.
- **Snap turning**: 30/45° discrete rotation.
- **Stable horizon / cockpit**: 매 reference frame 의 제공.
- **Comfort rating**: Comfortable / Moderate / Intense — 매 store labeling.

### 매 응용
1. VR game design (Half-Life: Alyx, Beat Saber).
2. Training sim (medical, military, flight).
3. VR therapy 의 조정 (exposure therapy, PTSD).
4. Industrial design review.

## 💻 패턴

### Unity 의 vignette on locomotion (URP)
```csharp
using UnityEngine;
using UnityEngine.Rendering.Universal;

public class ComfortVignette : MonoBehaviour {
    [SerializeField] Volume volume;
    Vignette vignette;
    public CharacterController player;

    void Start() { volume.profile.TryGet(out vignette); }
    void Update() {
        float speed = player.velocity.magnitude;
        // 매 빠를수록 매 강한 vignette
        vignette.intensity.value = Mathf.Clamp01(speed / 5f) * 0.6f;
    }
}
```

### Snap Turn 구현
```csharp
public class SnapTurn : MonoBehaviour {
    public float snapAngle = 30f;
    public Transform xrRig;
    bool turning;

    void Update() {
        float x = Input.GetAxis("RightStickX");
        if (Mathf.Abs(x) > 0.7f && !turning) {
            xrRig.Rotate(0, Mathf.Sign(x) * snapAngle, 0);
            turning = true;
        }
        if (Mathf.Abs(x) < 0.3f) turning = false;
    }
}
```

### Teleport locomotion (XR Interaction Toolkit)
```csharp
// XR Interaction Toolkit 의 TeleportationProvider + TeleportationArea 사용.
// 매 thumbstick forward → arc raycast → release → fade-to-black → reposition.
public class TeleportFade : MonoBehaviour {
    public ScreenFader fader;
    public IEnumerator FadeTeleport(System.Action moveAction) {
        yield return fader.FadeOut(0.15f);
        moveAction();
        yield return fader.FadeIn(0.15f);
    }
}
```

### Frame rate budget guard (Unity profiler)
```csharp
void Update() {
    float dt = Time.unscaledDeltaTime;
    if (dt > 1f / 80f) {  // 12.5ms — 90Hz budget 위반
        Debug.LogWarning($"Frame {dt*1000:F1}ms — VR comfort risk");
    }
}
```

### Stable cockpit reference (vehicle VR)
```csharp
// 매 driver 시점 — 매 cockpit 매 항상 보이도록.
// 매 strong reference frame 으로 vection 감소.
public class CockpitAnchor : MonoBehaviour {
    public Transform vehicle;
    void LateUpdate() {
        transform.position = vehicle.position;
        transform.rotation = vehicle.rotation;
    }
}
```

### Async time warp / reprojection (built-in to Quest, Vision Pro)
```csharp
// 매 platform 자동 — frame miss 시 last frame 의 reproject.
// 매 dev 작업: 매 frame budget 안정 유지로 reproject 발동 X 가 best.
```

## 매 결정 기준
| 상황 | Approach |
|---|---|
| 매 first-person locomotion | teleport + comfort vignette |
| 매 cockpit (car, plane) | smooth motion OK + stable reference frame |
| 매 turning | snap turn (default), smooth turn (option) |
| 매 wide FOV + fast | vignette + reduced FOV |
| 매 cinematic camera | 매 user-controlled — automated camera 의 X |

**기본값**: 매 90Hz+, teleport locomotion, snap turn 30°, comfort vignette, motion-to-photon <20ms.

## 🔗 Graph
- 부모: [[Virtual Reality]]
- 변형: [[Cybersickness]] · [[Simulator Sickness]]

## 🤖 LLM 활용
**언제**: VR UX review, comfort rating 추정, locomotion design feedback.
**언제 X**: 매 individual susceptibility 진단 — 매 user testing 필수.

## ❌ 안티패턴
- **Cinematic forced camera**: 매 user 통제 X — 즉시 멀미.
- **60Hz VR**: 매 사실상 unusable.
- **Floating UI head-locked**: 매 head movement 따라 밀착 → vection.
- **Acceleration-heavy locomotion**: jerk 의 직접 유발.
- **No comfort rating disclosure**: 매 store policy 위반 (Quest, Steam).

## 🧪 검증 / 중복
- Verified (LaViola *3D User Interfaces* 2nd ed. 2017, Meta VR Design Guidelines 2024, Apple visionOS HIG).
- 신뢰도 A.

## 🕓 Changelog
| 날짜 | 변경 |
|---|---|
| 2026-05-08 | Phase 1 |
| 2026-05-10 | Manual cleanup — sensory conflict + comfort techniques + Unity patterns |