I am currently working on a live acted film that requires a scene with a spherical hologram projection of a space battle. The problem is that during the space battle, ships will be flying in and out of the hologram’s field of vision (think of the hologram display in Avatar). I thought that perhaps I could do this by creating a sphere and flipping it’s normals inward and then setting the normals to one sided to create a culling effect. Then I would place all of my lighting inside the sphere, that way any ships that move outside the sphere will not be lit and so will be easier to color key.
Unfortunately when I render the scene the sphere just renders as a big black globe. Any ideas how to render it so the reversed normals are transparent? Or better yet, does anyone have ideas on how to pull off this type of hologram effect?