  The concept of an invisibility cloak is a fixture of science fiction,
fantasy, and the collective imagination. However, a real device that could hide
an object from sight in visible light from absolutely any viewpoint would be
extremely challenging to build. The main obstacle to creating such a cloak is
the coupling of the electromagnetic components of light, which would
necessitate the use of complex materials with specific permittivity and
permeability tensors. Previous cloaking solutions have involved circumventing
this obstacle by functioning either in static (or quasi-static) fields where
these electromagnetic components are uncoupled or in diffusive light scattering
media where complex materials are not required. In this paper, we report
concealing a large-scale spherical object from human sight from three
orthogonal directions. We achieve this result by developing a three-dimensional
(3D) homogeneous polyhedral transformation and a spatially invariant refractive
index discretization that considerably reduce the coupling of the
electromagnetic components of visible light. This approach allows for a major
simplification in the design of 3D invisibility cloaks, which can now be
created at a large scale using homogeneous and isotropic materials.
