Min/Max altitude from image map ?

[Falcon]

This has me stumped, when it should be so easy.

I have a black/white image map showing the outline of an island. I'm generating the island itself with fractal terrain, but the outline needs to be what I have in the image file.

My first thought was to use the image map as a min/max setter, so that everything ON the island is clamped to water height + 1, while everything that should be underwater is clamped to water height - 1. But I can't figure out how to create that min/max filter.

I'm not dead-set on doing it that way. If there is a better way to accomplish my goal, I'm taking it.

[Oshyan]

Can you not just use the black/white map as a Blend Shader input to your fractal terrain node(s)? If you're starting with a flat, undisplaced planet, then you should be able to use a Lake object or another planet with a slightly larger radius than default, and a water shader, to get your island.

- Oshyan

[Falcon]

Yes, that works, but only if I forgo underwater terrain.

[Hetzen]

Use the same mask to invert blend another PF with the underwater features. You may even want to give the seabed fractal a negative displacement. If you blur your island masks you'll get better coastal features.

[Falcon]

I think "negative displacement" would solve my main problem.

Still, I would like to not use a different PF, but the same - just clamped to sea level. That can't be so difficult, can it? Clamping the displacement value?