Missing Person Finder Android App (AI + Firebase)

Project Objective

Build a secure and scalable missing person finder android app where police can post and manage missing person records, and citizens can report sightings with photos. The app performs on-device/edge AI face matching (or server-side) and notifies the police with geotagged evidence for rapid recovery.

How It Works

1. Police Flow: Police create a record with photos, name, age, last-seen location, and case status. Data is stored in Firebase Realtime DB.
2. Citizen Flow: Citizens receive nearby alerts and can browse the missing list.
3. Capture & Match: Citizen captures a photo; the app extracts face embeddings and compares with the police dataset (cosine similarity).
4. Verification: If score > threshold, the sighting + live location is sent to police for review. Final decision remains human-verified.
5. Assist & Educate: In-app AI chatbot answers safety queries; safety videos provide guidance on how to help safely.
6. Offline-first: Sightings queue offline and sync automatically when online.

Project Modules

Firebase Realtime Database Structure (Example)

{
  "missingPersons": {
    "caseId123": {
      "name": "John Doe",
      "age": 14,
      "gender": "M",
      "lastSeen": {"lat": 18.5204, "lng": 73.8567, "time": 1725345600},
      "photos": ["gs://.../caseId123/1.jpg", "gs://.../caseId123/2.jpg"],
      "embeddings": ["0.12,0.08,..."],   // normalized vector
      "status": "open",
      "createdBy": "policeUidA",
      "createdAt": 1725300000
    }
  },
  "sightings": {
    "sightingId987": {
      "photo": "gs://.../sightings/987.jpg",
      "embedding": "0.11,0.07,...",
      "location": {"lat": 18.52, "lng": 73.85},
      "similarity": 0.46,
      "topMatchCaseId": "caseId123",
      "byUser": "citizenUidX",
      "createdAt": 1725351111,
      "verifiedBy": "policeUidA",
      "verified": false
    }
  },
  "users": {
    "policeUidA": {"role":"police","name":"Officer A","station":"Pune"},
    "citizenUidX": {"role":"citizen","name":"(optional)","phone":"(optional)"}
  }
}
              

Sample Firebase Security Rules (High-Level)

// Realtime Database Rules (illustrative)
{
  "rules": {
    ".read": false,
    ".write": false,

    "users": {
      "$uid": {
        ".read": "$uid === auth.uid",
        ".write": "$uid === auth.uid"
      }
    },

    "missingPersons": {
      ".read": true,               // public read (or restrict to logged-in)
      "$caseId": {
        ".write": "root.child('users/'+auth.uid+'/role').val() === 'police'"
      }
    },

    "sightings": {
      "$sid": {
        ".write": "auth != null",   // any logged-in user can report
        ".read": "root.child('users/'+auth.uid+'/role').val() === 'police'"
      }
    }
  }
}
              

Key Features & Benefits

• End-to-end flow: police to citizen loop with verifiable evidence.
• AI-driven face match using embeddings + cosine similarity; threshold tuning.
• Privacy-first with Firebase Rules, role-based access, and minimal PII.
• Offline-first capture and automatic sync when online.
• In-app education via AI chatbot & safety videos to guide citizen actions.
• Scalable on Firebase; easy to extend with analytics and cloud functions.

What You Get