It’s the flashlight nose/mouth thingy put into overdrive by the subsurface scattering. I had the same problem when I started messing with it and came up with pretty much the same sollutions as are mentioned here none of them really worked but shadow bias did…
Turn off SSS completely as you don’t need it with humans as we’re not translucent all the way through, the only SSS you need for 99.999% of your renders is already burned into every realistic texture out there.
You’re right humans aren’t translucent all the way through that’s why its a SubSurface scatterer as part of the light is reflected but the skins subsurface. If you want proof that this is a real effect; take a powerfull flashlight, wrap your hand around it and see what happens (it helps if there isn’t a lot of other light so doing in the dark might be a good idea ) Once you’ve seen the difference you won’t want to render human skin without SSS it’s way more realistic.
I’m doing the test renders now: will post my results. Thanks for the tip.
No problem, it took me ages to figure this one out thought I’d save people some time :D
btw the effect does not always occur but sometimes the light hits the subsurface in such a way that nose and mouth light up adding an additional light can sometimes make it go away but if you don’t want to do that the only way to get rid of it is by adjusting the shadow bias.
Okay, starting with my own materials, I have made these tests.
My default shadow bias on my lights is 0.1 So I tried my materials at that, and then at a shadow bias of 1.0
bottom is at 0.1, top at 1.0
Ok so if that is right I’ve identfied a problem I’ve been having with the nasty striping when using SSS also your lighting setup seems to prevent to glowy nose something I’ve also seen in one of my portret setups.
I’ve never had to go above 4.
Your lights seem very bright to me and raising the bias seems to have helped but it might cause problems elsewhere with shadows.
I often find it is a act of balancing several things.