A feature-based proposal for blending freedom surfaces

Features have been recognized as a media for portraying intent and for communicating domain information from one context to another. They are extensively illustrated as orthogonal features. Sculptured surfaces are available in many products, and are modelled using freeform geometry on a variety of proprietery surfacing and styling systems. The representation of blending geometry between surfaces using freeform geometry such as NURBS (non-uniformal rational B-splines) is a labour-intensive process within traditional CAD and involves blending with multiple curves and surfaces. Automation is a highly desired process. One of the outcomes of the BriteEuram IMPRESS (BREU 7049) project has been to identify features as an ideal media to represent information in a freeform context for various product domains. The author is proposing a development of freeform features as a continuation of the freeform research completed within the IMPRESS project. The case for demonstrating freeform features was within the blending of aesthetic automotive A-class surfaces. This was achieved by identifying, parametrizing and developing an example of a feature for freeform blending using a multiple combination of freeform curves and surfaces, and continuity refinement functions.