Hi,
I have a mesh geometry that represents a bunch of mountains, with lots of peaks and valleys. Is there a good way to grab all the valley points? In SOPs, I suppose I could use some combination of the measure SOP's curvature measurement and vertical normals. But I'm in POPs, not SOPs. I've tried comparing the current point to its neighbors, but if you have a valley that's not completely level, that test fails, as the down-valley points are lower than the current point. And, my valleys don't nicely coincide with the mesh orientation either!

– Antoine

I've tried this before in SOPs

I'm assuming your mesh cache first lives in SOPs…

1) N to temp attrib(tempN)

2) Attrib transfer the tempN to itself with a surrounding pt count of like 10(depeneds on mesh density)

3) Dot product of N.tempN

basically compare the N to surrounding Normals, and if the dot product falls within a certain range then there you go. (well it's kind of like the curvature sop…)

This may or may not work in a pop context…