The author gave some details about the method, which I tried to reproduce. In this post, I present the different steps from the calculation in my favorite spatial R ToolBox to the rendering in QGIS using a specific blending mode.
The code is given at the end of the article.
Data used in this post is from OpenStreetMap contributors :
Get it on OSM Metro Extract or GeoFabrik
Data used in this post is from OpenStreetMap contributors :
Get it on OSM Metro Extract or GeoFabrik