The embedding diagram
Equatorial plane of the Reissner-Nordstrom black-hole metric
(expressed in terms of optical geometry) is embedded in the Poincare surface (the sphere).
Parameters of this animation are: Black-hole charge in the range 0--M,
compactness parameter in the range 4--80. (Colours of the surface have no meaning; these are
just for clarity of the graph.)
For technical details, see our paper.