The Brazil help talks about getting the correct IOR for something like whiskey in a glass by having a single surface for the whiskey/glass interface with a calculated IOR. How do I set things up for something metal embedded inside the glass? I can't put an "IOR" on the metal.
If it helps, or just to ask for more general help, I'm trying to make a very realistic looking and hopefully working LED, with a light source that's photon-capable. So the problem I've got in the original post is that the emitter and reflector and whatnot that's encased in the (are they glass or plastic?) housing doesn't look right, the IOR is wrong somehow.
Maybe I'm over-thinking this, from the sound of the reply, and just have the wrong IOR for the casing. If I put a metal something inside glass, the IOR for the 'metal/glass' interface would be IORmetal/IORglass which would be a big fat 0, so I shouldn't have to actually do anything special for an opaque object 'inside' glass/plastic/water?
I don't think you need to do that division for the refractive index in your case... in fact it doesn't apply if only one object is transparent. The opaque object may have an index of reflection but I don't think this will need to change. Does your result look 'wrong' to you? Like I said, I'm assuming I know what the scene is and could be misinterpreting your question.