Point-based CADCAM

During the design stage of free-form surfaces (e.g. car bodies), it is important that a certain level of geometric quality is attained for aesthetic, functional and manufacture reasons. Although present CADCAM systems offer tools for quality assessment and improvement (e.g. reflection lines), they are time consuming and require specialist knowledge. This is partly due to the difficulty in imposing geometric quality constraints on forms traditionally used in CADCAM (e.g. Bezier and NURBS). Our aim is to develop a system in which a surface is defined by a sparse grid of points that may be interrogated using point-based algorithms. The basis of such algorithms is the ability to derive intermediate surface points that guarantee the necessary geometric constraints (e.g. curvature monotonicity). These algorithms form the building blocks of a CADCAM system that inherently produces good quality surfaces. This will certainly reduce and possibly eradicate the geometry refinement stages between design and manufacture. We present an overview of the point-based system with examples of the system in use.