Hi Matt,
The maths I understand; the rest...... well, let's say, I'm confused but I'll have another look, rereading all the time what you have written and see if I can understand further.
As I am using TU's Snow Pack, I'll have to look further into it to see what you mean (I am thinking you're referring to the node chain; Colour Adjust > Power Fractal > Thick Snow_1_1 that is connected to the mask input of the output Thick Snow_1_1_1? Sorry if I am using incorrect terminology; it's all part of the learning curve).
One of the problems with Intersect Underlying is that there is no entry concerning it in the wiki that I can find (The Surface Layer Effects tab is still a WIP) so I have very little to go on wrt understanding how it works or, tbh, what it does (I believe it "reads" information from the layer below and "reacts" accordingly)...
I am forever reading users complaining about the incompleteness of the wiki and I do realise that given the nature of how Terragen works, it can be quite difficult to explain certain concepts/workings of the program.
There is also the constant request for tutorials and, sadly, good artists don't necessarily make good tutorial writers.
Ironically, having been a teacher for 25 odd years, I am pretty good at writing tutorials and I would happily do so, for free; now all I have to do is learn Terragen first..........
EDIT:- I was just about to post this when you posted, Martin.
QuoteYes Matt, I noticed Erwin somehow used an "intersect underlying" layer as a mask as well.
OK, I am now even more confused, so I do hope you'll explain what I did wrong.
I freely admit to being quite ignorant of the inner workings of your snow shader so I copied how it was connected in your TUSnow2.tgd.
At least I thought I had......(?)