Standards and Data Exchange

Abstract

The central theme of this chapter is the relationship of NURBS geometry, as practiced in this book, to other methods of representing curves and surfaces, and to several important standard formats for the exchange of geometric data between two systems. We have used a specific form of knot vector throughout this book; Section 12.2 discusses another type of knot vector and the conversion between the two types. Section 12.3 describes how NURBS curves and surfaces are defined within the three standards: IGES, STEP, and PHIGS. We remark that our NURBS are compatible with the NURBS of these standards (with the exception that IGES and PHIGS allow discontinuous curves and surfaces). Finally, Section 12.4 gives some general guidelines for exchanging geometric data between a NURBS system and another system.