Summary: |
Over the last decade Computer Aided Design (CAD) systems have found their way inthe building industry and have become a mayor tool for defining the shape of a prod-uct. However, CAD systems still do not really seem to aid the design process duringall its stages. They fail to assist the early design phases, where shape definitions arenot fixed yet, but exist stilr as roughly sketched contours.This paper investigates shortcomings of the state of the art CAD-systems, with regardto their application in all design stages, especially within the building industry. Anew approach for shape definition is intrduced. This approach, called ‘SemanticTopology’, should be able to bridge the gap between advanced product model struc-tures and conventional geometric modelling. ’This implies bringing in features for: - adjusting the tolerancing level,eg, a liberal tolerancing level in the early design stage ending in the acceptedmanufacturing tolerances after the completion of the final design.defining shape constraints,shape constraints should clearly define the modelling freedom to define a cer-tain shape. This feature is particular important for realising concurrent engi-neering.modular structures, in contrast to monolithic structures, are essential to ma-nipulate product models, standard part libraries and very large shape models.a consistent shape decomposition helps to integrate shape definition withproduct definition.It is insportant to stress that Semantic Topology does not introduce a new kind ofgeometric modelling, yet it acts as an intermediary layer between a product modelkernel and a geometric model.I making geometrical structures fit for modular handling,- shape decomposition support, |