Back in the 1980s, there was a somewhat lame movie called "The Last Starfighter" whose main claim of distinction was the fact that all of the special effects were rendered on a computer. If memory serves, they used a Cray X-MP supercomputer to render the images at a resolution of about 4000 x 6000, roughly equal to the grains on movie film. It took one second to render each image (24 frames per second for movies, 30 frames per second for NTSC TV), and this was in the mid-1980s.

Technology has improved dramatically since then. The old DEC Alpha chip had versions with similar or even greater math processing power to some of the 1980s Cray supercomputers. There are some very powerful chips out there available for desktop workstations from Silicon Graphics and other companies, and some of them are even grouped into Beowulf-style clusters to run in parallel.