Setting transparency on mesh from inside, but not outside Horrible title, I know. I doubt transparency is even what I need. Hopefully I can clarify what I'm trying to experiment with:

Two ico spheres share the same position, subdivisions, and rotations. Only difference between them are their scales, so one is inside the other. Outer sphere has an opaque material applied. Is there a material, or effect I could apply to the inner sphere, that would allow a camera object at the centre to see outside of the two spheres?

Only thing I can think of is to put a camera object at the normal of each face on the external sphere, then assign individual materials to the corresponding inner sphere faces which would display the camera views. However, that seems like a time intensive task, and a nightmare to organise. Wondering if there's a more elegant way to achieve the same effect.
I want to thank you for this question because I learned something in researching the answer.

Things have changed. Here's how you can do this easily in 2.8.

There is a backface culling option when in Edit Mode from the Viewport Shading Menu pulldown, BUT this is NOT what you want. Leave it alone. :)



THere is another backface culling option in the Materials tab of the Properties Panel. THIS is what you want. Make sure it is checked.



Your camera will now render what is on the outside of any object with this material assigned to it, but not what is on the inside of it.

It feels good to have finally learned how this works just now. :)