Adding random walk SSS to alsurface please

[Bigguns]

Ha ok, yeah I had to crank up the output too, but I was not using phase function at 0 though

[jasonhuang1115]

Many thanks for posting those examples, guys! Super helpful. I just recently noticed the complementary hue effect that Lele mentioned on AlSurface. Apparently it appears on the scatterVolume as well.
I wonder how would you validate the "accuracy" of subsurface effect of either shader? Is there a ground-truth rendering to tell us that observed blu-ish or grey-ish effect in certain areas is incorrect?