Thanks for the reply.
I have already tried that. I used Gimp to blur the edges, but it causes me to lose my shape the same as if I blurred in WM. I just had an idea how to accomplish this correctly as I was typing, so Iwill give that another go in a minute. I got a better results previously using the smudge tool, and when I was getting somewhere close to what I wanted, I read that to create different regions/biomes/terrain types, I had to have a landscape generator for each area and draw my land out making sure the regions meet correctly. Which is why I started to hand draw the shape.
Maybe a suggestion for future builds of WM is to have sample terrains or a tutorial using a mask and file input. Bonus points for a few terrains with multiple landscape types like coastline leading to mountain range covered in snow and on the other side of that is a slope down to a swamp/jungle leading to a desert. The sample scenes in WM cover the basics, but there’s none for advanced creations like what I had planned.
I take it to do what you are suggesting about the coast to land transition, I use a gradient as a mask?