Cut one object's reflection from one other object.

Hi folks.

I have a bit of a problem with emitter reflections. I have an emitting icosphere inside a hollow icosphere. The hollowed ico was created by putting a sphere inside another larger sphere and adding the boolean modifier, it has a pure glass colour, works a treat and looks lovely. However… I can see the emitter through the ‘glass’ but the emitter doesn’t light up anything outside the glass, as if the light from the emitter only travels through the glass directly to the camera. It lights internally all the angles of the glass ico beautifully. To get around the problem of it not casting light I put another smaller emitter outside of the glass sphere, only emitting down and out, and hid it from the camera. This cheat is barely noticeable and looks really nice. So far so good… Now, there is also some water in the scene and both emitters reflect. I want the real emitter to reflect in the water, but not the secondary emitter because it’s not meant to be there. I can turn off the ‘Glossy’ in Rays in the Object settings which stops it reflecting, but then it doesn’t light anything around it.

So, is there anyway I can set the water object, (which is basically just a plane/miror) not to reflect the fake emitter object, and only that object, but to still accept the light that is being cast by it?

Does this make sense?!

No, if there is a way to make a single point thickness glass icosphere that lets the light through correctly that would be an answer. I have tried putting an emitter inside a solid glass icosphere, but the light just doesn’t get out of it.

Any help or suggestion on this one would be very much appreciated.


Actually, I’m doing some testing in a sandbox, and light does pass through the hollow sphere. So why in my large scene do none of the diffuse objects reflect the light?


It’s a Caustic problem. I’m abandoning this approach and adding spots. I didn’t want to do this but hey ho!

And, for the scene, they actually work better! Solved!