Realized with the assistance of Wolfgang Möller.
" The graphic Eikonal … from nearby one sees just a tangle of black curves, but from afar it looks like … (squinting or viewing in dim light helps in seeing what’s “behind” Eikonal).
This image, programmed by Wolfgang Möller, is a solution of the eikonal equation of geometric optics. The curves are the wavefronts of a light wave emanating from near the center of the picture and traveling through a medium of variable refractive index. "
Manfred R. Schroeder