Subsurface only works when light is inside mesh? Or: Subsurface only functions for 2D meshes?

anonymous_user_fbaa1f9f
Mon, 04 Apr 2016 21:18:05 +0000
Rendering

I am trying to create a floor lamp with a shade. The shade is a hollowed tube with thickness–i.e. it’s a double-sided surface. When I place point lights inside of the tube, subsurface might as well not be turned on at all. It looks totally horrendous, and it fails to illuminate the room around the lamp.

Through a little testing, it appears that subsurface only allows light through a surface if the light source is INSIDE that surface. Consider the attached screenshots.

I feel like I must be missing something here, because I don’t understand how subsurface can be used for anything if it only works in this bizarro-world sort of scenario. Am I supposed to make the lampshade a solid cylinder? Am I supposed to make it a single-sided zero-thickness tube? Both of these solutions are obviously unacceptable (they would look weird as hell).

Thanks for any help!

EDIT: Oh, I should add: This happens no matter what opacity is set to on the material (it seems to have no effect at all, in fact). Also, this behavior is in stark contrast to what is described here: Using Subsurface Scattering in Unreal Engine Materials | Unreal Engine 5.2 Documentation

In that link it shows light passing all the way through to the other side of the chair, which is lit up. In my example screenshots, the backside of the mesh illuminated by the exterior light is pitch black.

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