How does fortnite created different biomes on a tiled landscape?

Notice the red line I drew - it is the border between the snow areaa and the forest area.
How do you make that? It’s obviously not square.

Also, you keep using the concept “tile” but it’s not an Epic concept, so I’m sort of guessing what you mean here.
Can you define it so we can be sure we’re talking about the same thing?

Edit:
Successfully attached the image this time.

Each landscape in a world composition level is a tile. It behaves like a tile and hooks up like a tile - provided the size is correct.
together they form the whole (world).

The regions in any game, not just fortnite, don’t usually have a “solid” border.
They transition gradually.

You can achieve this as explained above with a variable layer material.

you manually paint the specific landscape to have the snow layer with whatever transition you like and finally merge it to the same material used within the other tiles/maps so that it is in fact seamless.

[USER=“3140864”]MostHost LA[/USER] I just wanna say that instead of explaining everythnig you did, you could of just said “hand paint”.

I believe I commented about it previously but I’ll do it again in cae I didn’t:

So one can’t actually paint the borders, ,you actually need to paint the entire landscape. That is, if we take the fortnite example, the best thing you can do
is clear the entire map with the “light forest”, paint all the “dark forest” areas, then paint all the “snow areas”, and then paint all the “desert areas”.
Then go in and manually adjust the the borders in a more thoroughly manner.

While I know this is an option, it just seems like a lot of manual work, specially on really big maps.
Do you believe that is what big companies actually do?

I think you entirely miss the point.

IF the flat png used for the “Grass” layer is called for, but you are in the snow biome, are you going to display the Grass layer? No… your grass layer becomes the snow. You can therefore swap (or rather than swap use the png on a different layer) grass textures with snow textures.

Now, when you work outside the engine and produce the masks, you just need to keep in mind HOW you blend it.

Very commonly, one layer is exactly the same across all tiles and is used for blending, while the others are instanced separately (by changing the images in the material along with other parameters your master landscape material allows for).

Personally, I use QGis to produce the base layers on which to improve upon.

If you have world machine, I’m sure it can also produce the “famous” splat maps that people often wonder about in formums.

If you use blender you can paint an auto material and bake out the different layers at the appropriate resolution. Mind you that this isn’t the same as Qgis accuracy or World Machine, but as a starting point it’s rather effective.