Oh wow, all these great replies already! Thanks everyone.
Huge print rez version (1.8M) here
The knitted jumper is geometry, which was made using a couple of plugins, decorate, by an ex colleague of mine Roger Fransen, and clone by itoo software. So, I modelled one stitch of knitting using renderable splines, then two clone modifiers to make it into a flat surface, then decorate to conform that over a low resolution model of the jumper. Finally, I scattered some fine fluffy hairs over the jumper, which helped to make it look soft.
Unfortunately decorate is max8 only If anyone interested in writing max plugins wants to steal the idea for decorate then go for it, Roger has moved on to bigger and better things so won’t be updating it anytime soon, and its a shame not having such a cool plugin in newer versions of max.