This is a QGIS plugin which can be used to generate curved flow lines for use in creating an OD flow map, such as the one seen below:
Source: Jenny et al (2016)
The plugin uses iterative force-based approach in which each flow is represented by a bezier curve. Each curve's control point has various forces acting on it which cause it to be repelled from other nodes and curves, attracted to the straight-line midpoint, and to improve angular resolution at nodes. The algorithm is based on that described in the paper Force-directed layout of origin-destination flow maps by Jenny, et al.
This is a very computationally expensive operation, so it is only recommended for small- and medium-sized data sets. Data sets up to approximately 20 flow lines should process in several minutes on most machines. A data set with 130 lines was tested on the development machine, and processing took several hours.
QGIS >=2.0
The plugin has been tested on QGIS 2.18 on Linux and Windows.
Copy files into a folder in your QGIS plugins directory and enable the plugin in the QGIS plugin manager.
Pull requests and bug reports are welcome.
- Patrick Malcolm - Initial work - patmalcolm91
- Details of Good Flow Maps - a good blog post about setting up flow map symbology in QGIS