GeoJSON network simplification using raster image skeletonization and Voronoi polygons
The load GeoJSON file, use Voronoi polygons to simplify network, and output GeoPKG layers corresponding to the input, simplified and primal network
The sample data set is of Queenstreet in Edinburgh kindly shared by Robin Lovelace
The run.sh script setups a python virtual environment and executes the script against a data file in the data directory
$ ./run.sh
The run.sh script optionally takes a filename and file-extension. To simplify a file, say somewhere.geojson and output to GeoPKG files sk-thing.gpkg and vr-thing.gpkg
$ ./run.sh somewhere.geojon thing
In an activated virtual environment, the following creates a simplified network by applying skeletonization to a buffered raster array
(venv) $ ./skeletonize.py data/rnet_princes_street.geojson
In an activated virtual environment, the following creates a simplified network by creating set of Voronoi polygons from points on the buffer
(venv) $ ./voronoi.py data/rnet_princes_street.geojson
The script assumes a working command line environment with an accessible working python3 environment, with an optional working ogr2ogr executable
The ./run.sh script will create a python virtual environment with dependencies in the venv directory, activate this environment and create test GeoPKG and, if ogr2ogr is installed, GeoJSON files
To replicate the creation and activation of a python virtual environment in the run.sh script, execute the following commands
$ python3 -m venv venv
$ source venv/bin/activate
$ pip install --upgrade pip
$ pip install --upgrade wheel
$ pip install --upgrade -r requirements.txt
Where the module dependencies are contained in the requirements.txt
Once installed to activate a virtual environment
$ source venv/bin/activate
Both are the skeletonization and Voronoi approach are generic approaches, with the following known issues:
- This does not maintain a link between attributes and the simplified network
- This does not identify a subset of edges that need simplification
- The lines are a bit wobbly