Introduction In 1980 Jim Blinn produced computer graphics animations for Carl Sagan's PBS series Cosmos. For the 11th episode of the series, entitled: "The Persistence of Memory" he made an animation of the DNA helix. In order to model the helix he proposed approximating each atom by a Gaussian potential, and using superposition of these potentials to define an iso-surface. He then used ray-tracing to render the animation and named the resulting structure "blobby objects" [1]. Shortly thereaf...
