Landscape material - Lerp based on roughness

Hi.

So, I’ve been trying really hard to come up with a way to create a realistic looking landscape material. Anything I tried, would also end up with some sort of tiling.

Anyway, I think I came up with an idea, which seems to work but I’d like to know how to implement it on a much larger scale. Basically, I’m trying to solve tiling for furthest distance, so I realized I needed to just use a color, rather than a texture, and then Lerp between it, and a darker version of it based on some sort of variation, or distortion.

So, here’s the deal: I created a test landscape using world machine and imported it into unreal engine.

I then created a roughness map using world machine. Something like this:

I then went ahead and created a simple material, something along the lines of this:

And finally, here’s what my landscape looks like:

So, this is pretty cool, BUT:

How could I accomplish something like this in a tiled build? And I mean, a really large map. Will generate a huge variation map like one here even if the map is huge? Or, is there a way to do that within unreal engine somehow? Is there a node or something, that would allow me to sample the landscape, and return whether the slope, or convexity, or something like that?

Anyway, any input on this matter will be highly appreciated!