The procedure Pcp2Nurb maps between planar-cut polyhedra andstandard nonuniform rational B-spline (NURBS) surfacerepresentation (linearly trimmed bicubic B-splines and untrimmedbiquadratic B-splines). A description of a preprocessing stage to mapfrom unrestricted control polyhedra to planar-cut polyhedra is included,with details on preserving features such as sharp edges. The surfaceresulting from Pcp2Nurb stays within the local convex hull of theplanar-cut polyhedra. Pcp2Nurb can be used as a component of a systemthat allows a general smooth surface design environment but produces astandard representation for the resulting surface.

This is primarily an algorithm presentation, with the necessarytheory summarized and references given for further details. Afamiliarity with the terminology of surface representation is assumed.The environment for the software is clearly indicated, with a sampleresulting surface displayed using a standard viewer. The primaryaudience for this paper includes graphics software developers andresearchers dealing with surface representation; however, with thewell-chosen figures provided, this work should also be of value toothers, such as potential users.