Models of cloth generally fall into three groups: the geometric-mechanical structure at yarn crossings, secondly the mechanics of continuous elastic sheets and thirdly the geometric macroscopic features of cloth.^[11] To date, making the clothing of a digital character automatically fold in a natural way remains a challenge for many animators.^[12]

In addition to their use in film, advertising and other modes of public display, computer generated images of clothing are now routinely used by top fashion design firms.^[13]

The challenge in rendering human skin images involves three levels of realism: photo realism in resembling real skin at the static level; physical realism in resembling its movements and functional realism in resembling its response to actions.^[14]