Custom Map Downloader

A QGIS plugin for downloading high-resolution, georeferenced map imagery from any loaded layer.

Description

Custom Map Downloader allows users to generate georeferenced GeoTIFF images from any loaded map layer in QGIS. By providing a center point (latitude/longitude), desired Ground Sampling Distance (GSD), and output dimensions, the plugin automatically computes the correct map extent, renders the specified layer at the requested resolution, and exports a fully geotagged TIFF file.

Perfect for extracting satellite imagery, creating training datasets, generating offline maps, or producing custom map exports for simulation and analysis workflows.

Screenshot

Custom Map Downloader plugin interface

Features

• ✅ Export Any Layer - Works with satellite imagery, XYZ tiles, raster layers, and vector tile layers
• ✅ Precise Positioning - Specify center point using latitude/longitude coordinates (EPSG:4326)
• ✅ Custom Resolution - Configure Ground Sampling Distance (GSD) in meters per pixel
• ✅ Flexible Dimensions - Set custom output dimensions (width × height in pixels)
• ✅ Optional Georeferencing - Toggle between georeferenced GeoTIFF or plain TIFF export
• ✅ Automatic Layer Loading - Optionally load exported image directly into QGIS
• ✅ Progress Feedback - Visual progress dialog during export
• ✅ Proper Metadata - Full GDAL georeferencing with EPSG:3857 projection
• ✅ Optimized Output - LZW compression and tiling for efficient storage

Installation

From QGIS Plugin Repository (Recommended)

1. Open QGIS
2. Go to Plugins → Manage and Install Plugins
3. Search for "Custom Map Downloader"
4. Click Install Plugin

Manual Installation

1. Download the latest release from GitHub Releases
2. Extract the ZIP file
3. Copy the custommapdownloader folder to your QGIS plugins directory:
   • Windows: C:\Users\[username]\AppData\Roaming\QGIS\QGIS3\profiles\default\python\plugins
   • macOS: ~/Library/Application Support/QGIS/QGIS3/profiles/default/python/plugins
   • Linux: ~/.local/share/QGIS/QGIS3/profiles/default/python/plugins
4. Restart QGIS
5. Enable the plugin in Plugins → Manage and Install Plugins → Installed

Usage

Quick Start

1. Load a Map Layer

   • Add any map layer to QGIS (e.g., Google Satellite, OpenStreetMap, Bing Maps)
   • Ensure the layer is visible in the Layers panel

2. Open the Plugin

   • Click the Custom Map Downloader icon in the toolbar, or
   • Go to Plugins → MapDownloader → Download GeoTIFF from Map

3. Configure Parameters

   • Coordinates: Enter latitude and longitude in decimal degrees
     • Example: Latitude: 28.6139, Longitude: 77.2090 (New Delhi)
   • Resolution: Set Ground Sampling Distance (GSD) in meters/pixel
     • Default: 5.0 m/pixel
   • Dimensions: Specify output width and height in pixels
     • Default: 5000 × 5000 pixels

4. Select Layer

   • Choose the layer to export from the dropdown menu
   • The list automatically refreshes to show all loaded layers

5. Choose Output Path

   • Click Browse... to select where to save the file
   • Recommended format: .tif or .tiff

6. Configure Export Options

   • ☑️ Add georeferencing metadata: Creates proper GeoTIFF with spatial reference (recommended)
   • ☑️ Load exported image as layer in QGIS: Automatically adds result to your project

7. Export

   • Click OK to start the export
   • A progress dialog will show during rendering
   • Success message will confirm completion

Default Settings

Parameter	Default Value
GSD	5.0 meters/pixel
Width	5000 pixels
Height	5000 pixels
Georeferencing	Enabled
Load as Layer	Enabled

Output Formats

With Georeferencing (GeoTIFF)

• Format: GeoTIFF with full GDAL metadata
• Projection: EPSG:3857 (Web Mercator)
• Geotransform: Includes pixel size and geographic extent
• Compression: LZW compression with tiling
• Bands: 4 (RGBA)
• Compatibility: Works with all GIS software (QGIS, ArcGIS, GDAL, etc.)

Without Georeferencing (TIFF)

• Format: Standard TIFF image
• No spatial metadata
• Smaller file size
• Faster export
• Use case: When you only need the image without coordinates

Use Cases

• 🎯 Machine Learning: Generate training datasets for computer vision models
• 🗺️ Offline Maps: Extract map tiles for field work without internet
• 📊 Reports & Presentations: Create custom map exports at specific resolutions
• 🚁 Simulation: Generate georeferenced imagery for UAV/drone simulations
• 🔬 Research: Export precise areas for spatial analysis
• 📱 Mobile Apps: Create map tiles for mobile applications

Technical Details

Coordinate Systems

• Input: EPSG:4326 (WGS84 - Latitude/Longitude)
• Processing: EPSG:3857 (Web Mercator)
• Output: EPSG:3857 with proper geotransform

Rendering

• Uses QgsMapRendererParallelJob for efficient parallel rendering
• Supports all QGIS-compatible layer types
• Renders at exact specified resolution

Georeferencing

• GDAL-based georeferencing with proper geotransform matrix
• Includes spatial reference system (SRS) metadata
• Pixel size calculated from GSD parameter
• Geographic extent computed from center point and dimensions

Requirements

• QGIS: Version 3.0 or higher
• Python: 3.6+ (included with QGIS)
• Dependencies:
  • numpy (included with QGIS)
  • GDAL/OGR (included with QGIS)
  • PyQt5 (included with QGIS)

Troubleshooting

Layer not appearing in dropdown

• Solution: The plugin refreshes layers each time it opens. If a layer is missing, close and reopen the dialog.

Export fails with "Invalid coordinates"

• Solution: Ensure latitude is between -90 and 90, longitude between -180 and 180. Use decimal degrees format.

Exported image has no georeferencing

• Solution: Make sure "Add georeferencing metadata" checkbox is enabled before export.

Image appears in wrong location

• Solution: Verify your input coordinates are correct and in decimal degrees (not DMS format).

Large exports are slow

• Solution: This is normal for high-resolution exports. The progress dialog shows the process is working. Consider reducing dimensions or GSD for faster exports.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

1. Fork the repository
2. Create your feature branch (git checkout -b feature/AmazingFeature)
3. Commit your changes (git commit -m 'Add some AmazingFeature')
4. Push to the branch (git push origin feature/AmazingFeature)
5. Open a Pull Request

License

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

See LICENSE for more details.

Author

Abhinav Jayswal

• Email: abhinavjayaswal10@gmail.com
• GitHub: @ashroo

Acknowledgments

• Built using the QGIS Plugin Builder
• Uses QGIS API and GDAL for geospatial operations
• Thanks to the QGIS community for excellent documentation

Support

• 🐛 Bug Reports: GitHub Issues
• 💡 Feature Requests: GitHub Issues
• 📧 Email: abhinavjayaswal10@gmail.com

Changelog

Version 0.1.1 (2025-11-25)

• Added LICENSE file (GPL v2)
• Fixed plugin packaging for QGIS repository
• Cleaned up metadata and documentation

Version 0.1 (Initial Release)

• Export georeferenced GeoTIFF from any QGIS layer
• Configurable GSD and dimensions
• Optional georeferencing toggle
• Automatic layer loading
• Progress dialog with visual feedback
• Support for EPSG:3857 projection
• LZW compression and tiling

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⭐ If you find this plugin useful, please consider giving it a star on GitHub!