To put clothes on their characters, computer graphic artists
usually simulate cloth by creating a thin sheet, then adding some sort of
texture. But that doesn’t work for knit sweaters. To make the image realistic,
the computer has to simulate the surface right down to the intricate
intertwining of yarn.
So scientists must, in effect, teach computers to knit – and
graphic artists have to painstakingly model the 3-D structure of every stitch.