UX3D-haertl
commented
5 days ago High roughness for transmission looks up a small mipmap of a rendered texture without transmission. Since there is emissive light in the scene it is blended into the mipmap. The same problem occurs if the background is non black -> If you zoom in far enough that the emissive elements/background is not visible, the illumination disappears.
If IBL and point lights are disabled:
If IBL is disabled, the roughness texture looks too bright:
It should also change while moving the camera around it, but it does not. (The assets without transmission texture seem to work)