I’ve been playing with Rhino on and off since around 97’ish (or whenever I was in middle school). Glad to be a in position where I can actually get it myself, and the improvements since I’ve played with it last are amazing - especially the emission materials!
Anyway, I’m not sure if this is a bug or intended behavior, but I noticed that a custom material with self-illumination doesn’t seem to have that illumination pass through transparent materials, such as glass, or reflect off surfaces when there’s no other light source.
I’ve tested this against both the Rhino Renderer as well as the ProRender engine.
In this example, the middle box has a glass material, the boxes on the left have the custom material with self-illumination set, and the right set of boxes have an actual emission material. The ground plane material is a polished metal.
Here are example renders with both active, and then each individual set active.
With Raytraced and Rhino Render in Rhino 7 the self-illumination is implemented to work only for the camera ray. That is why you don’t see the object through the glass when only it is in the scene and no other light is available.
For that indeed the Physically Based material and Emission material are the only good options. Moreover, the Rhino custom material does not have any provision for controlling the emission strength, whereas the two new materials Physically Based and Emission do provide means to control the strength.
