Edit: My attachment got eaten…
This is a spline mask generator that’s somewhat working that might be nice for inserting playable areas with less rough terrain, roads, or other things that should be manually specified rather than procedurally generated. In this example it’s being used to blend between a constant terrain and a rougher, fractal noise terrain. It’s not perfect particularly in areas that are very convex, because it’s using nearest distance rather than some sort of projection from spline space to make things smoother.