A line-art nonphotorealistic rendering scheme of scenes composed of fr
eeform surfaces is presented. A freeform surface coverage is construct
ed using a set of isoparametric curves. The density of the isoparametr
ic curves is set to be a function of the illumination of the surface d
etermined using a simple shading model, or of regions of special impor
tance such as silhouettes, The outcome is one way of achieving an aest
hetic and attractive line-art rendering that employs isoparametric cur
ve based drawings that is suitable for printing publication.