expo-arkit-body-measurements

📱 Expo module for ARKit body measurements using LiDAR sensor on iOS devices.

Features

• 🎯 Capture 3 body measurements using ARKit body tracking
  • Shoulder-to-shoulder distance (horizontal)
  • Waist circumference (estimated)
  • Waist-to-shoulder length (vertical)
• 📷 Uses iPhone/iPad rear camera + LiDAR sensor
• ⚡ Real-time body detection and measurement
• 🔒 Measurements saved locally with AsyncStorage

Requirements

• iPhone or iPad Pro with LiDAR sensor (iPhone 12 Pro or newer, iPad Pro 2020 or newer)
• iOS 14.0+
• Expo SDK 48+
• Expo development build (not compatible with Expo Go)

Installation

npm install expo-arkit-body-measurements

Configuration

1. Run prebuild

npx expo prebuild --platform ios

2. ⚠️ Manual registration required

Due to Expo autolinking limitations, you need to manually register the module.

Edit ios/Pods/Target Support Files/Pods-{YourAppName}/ExpoModulesProvider.swift:

Add the import:

import expo_arkit_body_measurements

Add to both module arrays (DEBUG and RELEASE sections):

ExpoArkitBodyMeasurements.self,

3. Install pods and build

npx pod-install ios
npx expo run:ios --device

Usage

import {
  startMeasurement,
  stopMeasurement,
  addMeasurementCompleteListener,
  ARKitPreviewView,
} from "expo-arkit-body-measurements";

// Start measurement
startMeasurement();

// Listen for results
const subscription = addMeasurementCompleteListener((event) => {
  console.log("Measurements:", event);
  // {
  //   shoulderToShoulder: 42.5, // cm
  //   waist: 85.2, // cm
  //   shirtLength: 65.8 // cm
  // }
});

// Use ARKit preview component
<ARKitPreviewView
  style={{ flex: 1 }}
  isActive={true}
  onBodyDetected={(event) => console.log("Body detected!")}
  onMeasurementReady={(event) => console.log("Measurement ready:", event)}
/>

// Cleanup
subscription.remove();
stopMeasurement();

Example Component

Check the example implementation in the package for a complete modal-based measurement flow with UI.

API

Functions

• startMeasurement() - Start ARKit body tracking session
• stopMeasurement() - Stop tracking session
• getMeasurements() - Get current measurements (if available)

Events

• onMeasurementComplete - Fired when measurements are captured
• onMeasurementProgress - Fired during measurement process

Components

• ARKitPreviewView - Native AR camera preview component
  • Props: isActive, style, onBodyDetected, onMeasurementReady

Troubleshooting

Module not found error:

• Make sure you've manually registered the module in ExpoModulesProvider.swift
• Run npx expo prebuild --clean and retry

Camera not working:

• Ensure you have camera permissions configured in app.json:

{
  "ios": {
    "infoPlist": {
      "NSCameraUsageDescription": "This app uses the camera to measure your body."
    }
  }
}

LiDAR not available:

• The feature is automatically hidden on non-LiDAR devices
• Test only on physical devices with LiDAR support

License

MIT

Contributing

Contributions are welcome! Please open an issue or PR.