Choosing multiple selections

[Xpleet]

I'd like to have my selective noise on two or three different altitudes, inbetween just smoothness.

How about making maybe 2 selections choosable for a Filter? Is that possible?

[cajomi]

You can solve that actually, if you use the height selection with 100% fuziness.
So, min altitude to max, max altutitude to max, slider fuziness for min altitute to max.

So, that selection now is a greyscale heightfield of the terrain.
Apply this selection to the selective noise, and set the selective noise strength to zero.

Push at least the "F" button beside the selection and the fitlercurve opens. The filtercurve enables you to set according to the heights where you want the smooth noise. Set there the fitler to max, else to min, with sharp edges or a bit smoother.