Use OpenStreetMap Areas in PCG

There are (at least) two kinds of foliage that you may add. Foliage that you want almost everywhere, such as grass or rocks, can be added using the Landscape Grass Types defined in the landscape material MI_Landscape.

Other foliage such as trees can be spawned only in some areas (using real-world data from OSM or any kind of vector file supported by GDAL). This is done thanks to a new PCG node called OGRFilter that filters out PCG points based on real-world geometries of forests or other areas.

You may also try to download landuse images using LandscapeTexturer for your georeference landscape, and then use these images to paint a specific layer where you want foliage.