---
id: wiki-2026-0508-alternative-realities
title: Alternative Realities
category: 10_Wiki/Topics
status: verified
canonical_id: self
aliases: [XR, Mixed Reality, MR/AR/VR Spectrum]
duplicate_of: none
source_trust_level: A
confidence_score: 0.9
verification_status: applied
tags: [xr, vr, ar, mr, immersive]
raw_sources: []
last_reinforced: 2026-05-10
github_commit: applied
tech_stack:
  language: TypeScript
  framework: WebXR/Three.js/Unity
---

# Alternative Realities

## 매 한 줄
> **"매 reality 는 spectrum 위 한 점이다."**. Milgram 1994 RV continuum 부터 modern XR (Apple Vision Pro M5, Quest 4, Snap Spectacles 6) 까지, alternative realities 는 physical reality 를 augment / replace / blend 하는 매 mediated environment 의 총칭. 2026 의 mainstream 은 passthrough MR + hand tracking + neural input.

## 매 핵심

### 매 Reality-Virtuality Continuum
- **VR (Virtual Reality)**: 매 100% synthetic — Quest 4, Vision Pro fully-immersive mode.
- **AR (Augmented Reality)**: 매 real + overlay — phone AR, Snap Spectacles, HoloLens.
- **MR (Mixed Reality)**: 매 real + virtual interact — Vision Pro passthrough, Quest 4 color passthrough.
- **XR (Extended Reality)**: 매 umbrella term — VR/AR/MR all-inclusive.

### 매 Tech Stack 2026
- **Display**: micro-OLED 4K/eye, varifocal, foveated rendering.
- **Tracking**: inside-out 6DoF, eye tracking, hand tracking 26-joint, body pose.
- **Input**: pinch + gaze (Vision Pro), neural EMG (Meta wristband 2026), voice (Whisper-on-device).
- **Compute**: Apple M5/Snapdragon XR3 — 매 on-device transformer inference.

### 매 응용
1. **Productivity**: Vision Pro virtual displays, Immersed VR coding.
2. **Training**: surgical sim, military, industrial maintenance.
3. **Therapy**: VR exposure (PTSD, phobia), pain distraction.
4. **Social**: Horizon Worlds, VRChat, Rec Room.
5. **Industrial Twin**: AR overlay on factory equipment.

## 💻 패턴

### WebXR session bootstrap
```typescript
// Modern WebXR (2026) — immersive-ar with hand tracking
const xr = navigator.xr;
if (await xr.isSessionSupported('immersive-ar')) {
  const session = await xr.requestSession('immersive-ar', {
    requiredFeatures: ['hand-tracking', 'hit-test'],
    optionalFeatures: ['anchors', 'plane-detection', 'mesh-detection'],
  });
  session.addEventListener('end', cleanup);
  await renderer.xr.setSession(session);
}
```

### Hand-tracking pinch gesture
```typescript
function onXRFrame(time: number, frame: XRFrame) {
  const refSpace = renderer.xr.getReferenceSpace();
  for (const inputSource of frame.session.inputSources) {
    if (!inputSource.hand) continue;
    const thumb = frame.getJointPose(inputSource.hand.get('thumb-tip'), refSpace);
    const index = frame.getJointPose(inputSource.hand.get('index-finger-tip'), refSpace);
    const dist = vec3.distance(thumb.transform.position, index.transform.position);
    if (dist < 0.02) emit('pinch', inputSource.handedness);
  }
}
```

### Passthrough + virtual content (Three.js)
```typescript
renderer.xr.enabled = true;
renderer.setClearAlpha(0); // 매 transparent — passthrough shows through
scene.background = null;
// 매 virtual cube anchored to detected plane
const anchor = await frame.createAnchor(planePose.transform, refSpace);
scene.add(makeCubeAtAnchor(anchor));
```

### Foveated rendering hint
```typescript
const layer = xr.glLayer;
layer.fixedFoveation = 0.7; // 매 0=off, 1=max — 매 30% GPU savings
```

### Eye-tracked gaze input
```typescript
session.requestReferenceSpace('viewer').then(viewerSpace => {
  // 매 Vision Pro / Quest Pro — gaze ray from eye
  const gazePose = frame.getPose(viewerSpace, refSpace);
  raycaster.set(gazePose.transform.position, gazeDirection);
});
```

## 매 결정 기준
| 상황 | Approach |
|---|---|
| Web 배포 | WebXR + Three.js |
| Native iOS | RealityKit + ARKit |
| Native Android | ARCore + Sceneform/Filament |
| Cross-platform native | Unity XR / Unreal |
| Enterprise 산업 | Vision Pro / HoloLens 2 |

**기본값**: 매 WebXR 시도 → 부족시 native.

## 🔗 Graph
- 부모: [[VR 엑서게임 (VR Exergaming)]] · [[HMD(Head-Mounted Display) 기반 엑서게임 환경]]
- 변형: [[Digital Twins]] · [[Digital Twins|Digital-Twin-Technology]]
- 응용: [[Beat Saber 엑서게임 연구(Beat Saber Exergaming Study)]] · [[Remote-Rehabilitation]]
- Adjacent: [[Visual-Effects-VFX]]

## 🤖 LLM 활용
**언제**: XR scene authoring, gesture pattern matching, accessibility caption generation.
**언제 X**: 매 real-time inner loop (latency budget 11ms) 에서 cloud LLM 호출.

## ❌ 안티패턴
- **VR 멀미 무시**: 매 locomotion = teleport/snap-turn 권장. Smooth locomotion 은 매 opt-in.
- **60fps 미만**: 매 90fps 미만 = motion sickness. 매 budget 11ms.
- **Untracked controllers**: 매 always handle controller-lost 이벤트.
- **Single-eye render**: 매 stereo render 필수 — single-eye 는 depth 깨짐.

## 🧪 검증 / 중복
- Verified: Milgram & Kishino 1994; W3C WebXR Device API 2024; Apple visionOS 3 docs.
- 신뢰도 A.

## 🕓 Changelog
| 날짜 | 변경 |
|---|---|
| 2026-05-08 | Phase 1 |
| 2026-05-10 | Manual cleanup — XR continuum + 2026 stack + WebXR patterns |
