Main Content ¶

The author and fellow interns digitally recreated a Bob Ross painting using QGIS by digitizing features into vector layers with assigned ‘Type’ attributes and various symbology effects including glow draw effects and gradient fills.

Challenge ¶

The GeoPackage required for QGIS Hub submission had a strict file size requirement of under 5MB (or 1MB compressed). The original file measured 9.7MB, primarily due to:

• High vertex counts from stream digitizing tool usage
• Unnecessary attribute fields retained from earlier project phases
• Potential residual or temporary data within the project

Solution Steps ¶

1. Remove Inessential Attribute Fields

Each layer’s attribute table was opened, editing mode enabled, and unnecessary fields deleted via the “Delete Field” button.

2. Export Layers with Symbology

Each layer was exported to a new GeoPackage by:

• Right-clicking the layer
• Selecting “Export” > “Save Features As…”
• Setting format to “GeoPackage”
• Specifying file path and layer name

3. Import QML Style Files

Since symbology wasn’t automatically included:

• Accessed “Layer Properties” > “Symbology” tab
• Selected “Load Style…” from the Style dropdown
• Chose “From file” in the Database Styles Manager
• Specified the previously created QML style file paths

4. Save Styles to GeoPackage

• Selected “Save Style…” from the Style dropdown
• Chose “In datasource database”
• Named the style identically to its layer
• Enabled “Use as default style for this layer”

5. Simplify Geometries

Using the Processing Toolbox “Simplify” tool:

• Selected input layer
• Set Tolerance to 0.001 to maximize vertex removal while preserving geometry
• Saved to the new GeoPackage
• Used identical layer names to allow style file recognition
• Applied the simplified data to the project

6. Compact Database

The final optimization step involved executing “Compact Database (VACUUM)” by right-clicking the GeoPackage file to remove any residual data from editing operations.

Results ¶

The optimization process successfully reduced the GeoPackage from 9.7MB to 1.6MB, exceeding the 5MB requirement and enabling upload eligibility.

Additional Resources:

• GeoPackage download: https://hub.qgis.org/geopackages/22/
• QGIS Open Day presentation: https://www.youtube.com/watch?v=SqcpSznqODI