Bridges 2011 Short Paper
Sundials from Toroid Surfaces
(Proceedings pages 605–608)
The circadian and annual geometry of the sun's rays will simplify
into what is termed the shadow planes model for sundial projection.
The author employs this model within a 3-D modeling program to
design a series of non-traditional sundials derived from toroidal
surfaces. These include the standard torus, as well as one eccentric
torus: the horn cyclide.