[kretash]

found an implementation here. http://fingswotidun.com/code/index.php/Eye

Don't know if it's the same one but it all it seems to do is scaling and clamping.

[Lerc]

I did that. It's a fairly direct conversion from the paper.

I'm guessing SmoothStep got converted for size or performance seasons, but it doesn't really do the same thing.

One of the tricky bits of procedural generation like this is that bugs get entrenched easily, because 'fixing' things can dramatically change the generated result. Perhaps that is what happened in this instance.