A Viewpoint-Dependent Approach to Ray Trace Free-Form Surfaces.

Arno Formella K. Müller A Viewpoint-Dependent Approach to Ray Trace Free-Form Surfaces. 143-156 2004 23 Comput. Graph. Forum 2 http://diglib.eg.org/EG/CGF/volume23/issue2/v23i2pp143-156_abstract.html db/journals/cgf/cgf23.html#FormellaM04