Design techniques for the definition of solid objects with free-form geometry

Abstract

Solid modellers and free-form surface systems have been evolving to a large extent separately for fifteen years or more. Free-form surface techniques must now be integrated into solid modelling systems, since many engineering parts involve this type of geometry. The present paper classifies free-form surfaces into four categories for design purposes, depending on the degree of geometric constraint involved in their definition. Proposals are then made for free-form design techniques suitable for use in solid modellers. A survey of existing solid modelling systems is included, with indications of the techniques currently available for the design of free-form solids.