@matan19 even if they are using World Composition (I am not sure about the map size), in the material there are ways to achieve this with a splat map with low resolution which will serve as mask. So, in the picture we got 4 different areas (dark green and light green as different vegetation types, snow and desert like) so each texture channel RGBA can have an image representing how to drive the material painting. The same splat map would be used to teach which foliage to apply (if any) and other scattered elements automatically. Extra details can be achieved with vertex painting on meshes at the transition portions.