Automatic minimaps in QGIS

This project responded to the need for the automatic generation of minimaps showing the service coverage of outdooractive's raster topo layer from different providers. It is a process that was carried out manually with any changes to the status quo, with no standardised style or underlying data.

I created a new QGIS project drawing basemap data from suitable custom-processed Natural Earth and OpenStreetMap tables in a shared PostGIS database. The new layer styles made sure to follow the visual identity of our primary hiking map, prioritising information shown, adding graphic features unavailable to webmapping, tuning down the basemap intensity and highlighting the coverage polygons. The polygons come from a new coverage layer with one feature per provider or map type, that serves as the reference layer for a map atlas cycling though the features and generating predesigned print layouts for every feature.

To account for the reduction in scale, because the coverage polygons are very detailed and lead to artifacts when rendered densely, a PostGIS materialized view was created, simplifying, merging and inflating polygons where needed to aid visualisation. This processing happens on the database server automatically whenever anyone changes the base polygon layer. The print layouts and map symbology were designed for three different image sizes to be used in the outdooractive web knowledge pages.

The overall time to refresh all minimaps dropped from days to a matter of minutes (essentially manipulating the polygons and exporting the print atlas layouts) and the results are currently being introduced into the platform.