NURBS DATA CONVERSION METHOD AND DEVICE

PURPOSE: To precisely and speedily evaluate and render non-uniform rational(b)- spline (NURBA) data by dividing a parametric surface into a series of strips decided by the tessellation of a v-parameter. CONSTITUTION: A graphics control processor 14 decides how to tessellate the v-parameters for the respective v-spans of the surface, evaluates a v-depending degree and a v-derived function, which follow the tops and the bottoms of the respective strips and transmits the obtained coordinate and the v-derived function to parallel floating point processors 16Q-16Z. The floating point processors 16W-16Z evaluate the u-depending degree of the top and bottom coordinates and the u-derived functions of the coordinates, and the u-depending degree of the corresponding v-derived function. The floating point processor 18 of a next stage converts the values into one set of a geometric coordinate and an apex vector related to a pair of points. The shaded image of a parametric surface based on NURBS can highly precisely be generated at high speed.