When an object is set to Camera Visibility = false it will be revealed by a refracted materal placed between the camera and the "hidden" object. It does not matter what material the hidden object has.
Sample scene attached and sample render below.
This also makes a fantastic VFX animation.
I'm not sure how to achieve such as result without the bug.
1 Solution
Transparent R Logo on glass (file attached): The transparency removes the refraction emission colour absorption but still reveals the "hidden" (camera visible = false) cube beneath.
Solid diffuse Red R logo on the glass (file attached): The logo behaves nicely. The refraction reveals the hidden cube.
Great effect.
I'm not sure the Camera Visible = false is working on the cube properly though. Unless there's a "refraction visibility" option that is set to True that is not currently exposed to Blender? The reflection visibility is working perfectly on the cube.
Bug? Not bug?
Nice effect though. Doesn't help when you put a hidden object behind a Window on a House or inside a Wine Glass or part obscured by a Glass Bowl.
Test file is simple for a reason. To remove all other complexity.
