Geometric and Feature modelling

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Freeform feature modelling: concepts and prospects

Abstract

Much research has already been done on regular-shaped features, but more complicated, freeform features are now demanded by product designers. 
Freeform shapes are mostly represented by low-level representations, such as Bézier, B-Spline and NURBS patches. Freeform features provide a high-level interface to these low-level representations. The purpose of freeform features is faster and more intuitive modelling with more guarantees for a high-quality design. In contrast to the traditional ways of modelling with freeform surfaces, where low-level entities such as control points and weights are used to interact with a freeform surface, the user is offered a set of freeform features whose basic shape is fully defined by intuitive parameters. The design-by-features approach offers good opportunities for validity maintenance, by which only models that satisfy certain pre-defined validity conditions can be created. In this paper, the most important concepts in design by freeform features are surveyed, and issues such as classification and parameterisation of freeform features and freeform feature recognition are described. Wherever appropriate, promising research prospects are indicated.