A Multi-Level Freeform Surface Feature Model

Feature modelling is a valuable technology to define and manipulate product models through advanced operations. Parameters and constraints can be included in feature models to represent particular design intent. In this way, entire families of shapes, not just specific instances, can be modelled. Freeform surface feature modelling, which extends the concept of feature modelling to freeform shapes, still suffers from a number of shortcomings as regards parametric modelling. In particular, it lacks good facilities to add new parameters to a model. We present a multi-level freeform surface feature model that can be used to implement such facilities. The model contains an unevaluated, a partially evaluated and an evaluated level. The paper describes the three levels and how these are generated.