There are lots of ways to modulate a clouds node. For this illustration, I decided to modulate the cloud bias value. When bias is low, middle values shift down. When bias is high, middle values shift up. Bias only affects middle values - the values 0 and 1 stay the same. This is why I like bias - keeping my boundary values 0 and 1 constant while shifting the in-between values is very convenient to keep the math simple.

So - here is the calculation and visualization of my cloud bias, which is my RIM.

k = 3
eu = Clamp(k * Min(U, 1-U))
ev = Clamp(2.5 * k * Min(V, 1-V))
edge = 1 - Min(eu, ev)
cb = .1 + .5 * Bias(edge, .02)
View(cb)

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)