Init

Author: pixelpawnshop

.github/workflows/deploy-frontend.yml

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+name: Deploy Frontend to GitHub Pages
+
+on:
+  push:
+    branches:
+      - main
+  workflow_dispatch:
+
+jobs:
+  build-and-deploy:
+    runs-on: ubuntu-latest
+    
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v3
+        with:
+          node-version: '18'
+          cache: 'npm'
+          cache-dependency-path: frontend/package-lock.json
+
+      - name: Install dependencies
+        working-directory: ./frontend
+        run: npm ci
+
+      - name: Build application
+        working-directory: ./frontend
+        env:
+          REACT_APP_API_URL: ${{ secrets.REACT_APP_API_URL }}
+        run: npm run build
+
+      - name: Deploy to GitHub Pages
+        uses: peaceiris/actions-gh-pages@v3
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          publish_dir: ./frontend/build
+          cname: ${{ secrets.CUSTOM_DOMAIN }}  # Optional: only if using custom domain

.gitignore

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+# Python
+__pycache__/
+*.py[cod]
+*$py.class
+*.so
+.Python
+build/
+develop-eggs/
+dist/
+downloads/
+eggs/
+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+wheels/
+*.egg-info/
+.installed.cfg
+*.egg
+MANIFEST
+
+# Virtual environments
+venv/
+ENV/
+env/
+.venv
+
+# Environment variables
+.env
+.env.local
+.env.production
+*.env
+
+# Google Earth Engine credentials
+backend/credentials/
+*.json
+!package*.json
+!tsconfig.json
+!frontend/src/data/*.json
+
+# IDEs
+.vscode/
+.idea/
+*.swp
+*.swo
+*~
+
+# Node
+node_modules/
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+.pnpm-debug.log*
+
+# React build
+frontend/build/
+frontend/.env.local
+frontend/.env.production.local
+frontend/.env.development.local
+
+# Misc
+.DS_Store
+*.log
+.cache/
+
+# Docker
+*.dockerignore
+
+# Cloud Run
+.gcloudignore

README.md

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+# SAR Flood Detection Application
+
+A web application for detecting surface water and flooding events using free Sentinel-1 SAR (Synthetic Aperture Radar) data from Google Earth Engine.
+
+## 🎯 Overview
+
+This application enables users to:
+- Draw an Area of Interest (AOI) anywhere on Earth
+- Automatically fetch the latest Sentinel-1 SAR imagery
+- Detect surface water using adaptive Otsu thresholding
+- Visualize results interactively with dual basemap options
+- Download detected water polygons as GeoJSON
+
+## 🏗️ Architecture
+
+```
+┌─────────────────────────┐
+│ Frontend (GitHub Pages) │
+│  - React + Leaflet      │
+│  - AOI drawing          │
+│  - Basemap toggle       │
+└─────────────┬───────────┘
+              │ GeoJSON AOI + params
+              ▼
+┌─────────────────────────┐
+│ Backend (Cloud Run)     │
+│  - FastAPI              │
+│  - Google Earth Engine  │
+│  - Sentinel-1 SAR       │
+│  - Water detection      │
+└─────────────┬───────────┘
+              │ GeoJSON water polygons
+              ▼
+┌─────────────────────────┐
+│ Visualization           │
+│  - Water overlay        │
+│  - Metadata display     │
+│  - GeoJSON download     │
+└─────────────────────────┘
+```
+
+## 🚀 Features
+
+- **Adaptive Water Detection**: Otsu thresholding automatically adjusts to local conditions
+- **Manual Overrides**: Advanced users can fine-tune detection parameters
+- **Dual Basemaps**: Toggle between OpenStreetMap and Esri World Imagery
+- **Test AOIs**: Pre-loaded test locations including historical flood events
+- **Real-time Processing**: Results typically return in 30-60 seconds
+- **No Caching**: Stateless design - download results as needed
+- **Free Data**: Uses Copernicus Sentinel-1 SAR imagery via Google Earth Engine
+
+## 🛠️ Technology Stack
+
+### Backend
+- **FastAPI**: Modern Python web framework
+- **Google Earth Engine**: SAR imagery access and processing
+- **Pydantic**: Request/response validation
+- **Google Cloud Run**: Serverless deployment
+
+### Frontend
+- **React 18**: UI framework
+- **Leaflet**: Interactive mapping
+- **Leaflet Draw**: AOI drawing tools
+- **Turf.js**: Geospatial calculations
+- **Axios**: API communication
+
+## 📋 Prerequisites
+
+### Backend
+- Python 3.10+
+- Google Cloud Platform account
+- Google Earth Engine service account
+- gcloud CLI (for deployment)
+
+### Frontend
+- Node.js 16+
+- npm or yarn
+
+## 🔧 Setup Instructions
+
+### 1. Google Earth Engine Service Account
+
+Follow the detailed guide in [docs/GEE_SETUP.md](docs/GEE_SETUP.md) to:
+1. Create a GCP project
+2. Enable Earth Engine API
+3. Create a service account
+4. Download credentials JSON
+5. Set up for local development and Cloud Run
+
+### 2. Backend Setup
+
+```bash
+cd backend
+
+# Create virtual environment
+python -m venv venv
+source venv/bin/activate  # On Windows: venv\Scripts\activate
+
+# Install dependencies
+pip install -r requirements.txt
+
+# Create .env file
+cp .env.example .env
+
+# Edit .env and set:
+# GEE_SERVICE_ACCOUNT_PATH=./credentials/gee-service-account.json
+
+# Place your GEE service account JSON in backend/credentials/
+
+# Run locally
+python run_local.py
+```
+
+Backend will be available at http://localhost:8000
+
+### 3. Frontend Setup
+
+```bash
+cd frontend
+
+# Install dependencies
+npm install
+
+# Run development server
+npm start
+```
+
+Frontend will be available at http://localhost:3000
+
+## 🧪 Testing with Sample AOIs
+
+The application includes 4 pre-loaded test AOIs:
+
+1. **Ahrweiler, Germany (2021 Floods)** - European flash flooding event
+2. **Sindh, Pakistan (2022 Floods)** - Massive monsoon flooding
+3. **Venice Lagoon, Italy** - Permanent water baseline
+4. **Sahara Desert, Algeria** - Dry control area (minimal water)
+
+Select these from the sidebar to quickly test the application.
+
+## 🚀 Deployment
+
+### Backend to Google Cloud Run
+
+```bash
+# From project root
+./deploy.sh
+
+# Or manually:
+cd backend
+gcloud run deploy sar-flood-api \
+  --source . \
+  --region us-central1 \
+  --platform managed \
+  --timeout 300s \
+  --memory 1Gi \
+  --allow-unauthenticated \
+  --set-secrets GEE_SERVICE_ACCOUNT=gee-service-account:latest
+```
+
+### Frontend to GitHub Pages
+
+```bash
+cd frontend
+
+# Update .env.production with your Cloud Run URL
+# REACT_APP_API_URL=https://your-cloud-run-url
+
+# Deploy
+npm run deploy
+```
+
+Or use the GitHub Actions workflow (see `.github/workflows/deploy-frontend.yml`)
+
+## 📊 Water Detection Algorithm
+
+1. **Data Ingestion**: Fetch most recent Sentinel-1 GRD imagery (last 30 days)
+2. **Preprocessing**: 
+   - Radiometric calibration
+   - Terrain correction (SRTM)
+   - dB conversion
+   - Lee speckle filtering
+3. **Feature Derivation**:
+   - VV and VH polarizations
+   - VV-VH difference
+   - Texture (local std dev)
+   - Slope
+4. **Adaptive Detection**:
+   - Otsu thresholding (or manual override)
+   - Polarization rules
+   - Terrain masking
+   - Texture filtering
+5. **Refinement**:
+   - Morphological operations
+   - Small object removal
+   - Geometry simplification
+6. **Vectorization**: Convert to GeoJSON polygons
+
+## 🎨 Advanced Parameters
+
+For fine-tuning detection (accessible via collapsible panel):
+
+- **VV Threshold (dB)**: Primary water backscatter threshold
+- **VH Threshold (dB)**: Secondary polarization threshold
+- **VV-VH Difference**: Polarization ratio limit
+- **Max Slope (degrees)**: Exclude steep terrain
+- **Min Area (pixels)**: Remove small noise objects
+- **Texture Window**: Spatial texture analysis window size
+
+## ⚠️ Limitations
+
+- **AOI Size**: Maximum 50×50 km (2500 km²) for real-time processing
+- **Temporal**: Uses most recent acquisition (last 30 days)
+- **Orbit**: ASCENDING pass only for consistency
+- **Resolution**: 10m Sentinel-1 ground resolution
+- **False Positives**: May occur in urban areas, wet soil, low-wind conditions
+- **Processing Time**: 30-120 seconds depending on AOI size
+
+## 🔮 Future Enhancements
+
+- [ ] Temporal change detection (before/after flooding)
+- [ ] Multi-temporal stacking for stability
+- [ ] Sentinel-2 optical cross-validation
+- [ ] Permanent water vs flood water classification
+- [ ] Export to Shapefile/KML formats
+- [ ] Time-series animation
+- [ ] Email alerts for new detections
+- [ ] Mobile-responsive design improvements
+
+## 📄 License
+
+MIT License - Free for educational and commercial use
+
+## 🙏 Acknowledgments
+
+- **Copernicus Sentinel-1** mission for free SAR data
+- **Google Earth Engine** for cloud-based processing
+- **OpenStreetMap** and **Esri** for basemap tiles
+
+## 📧 Contact
+
+For questions, issues, or collaborations, please open an issue on GitHub.
+
+---
+
+**Note**: This is a portfolio/demonstration project. For operational flood monitoring, consider additional validation and temporal analysis.