Retrospective Creation of Virtual Alternative Hierarchies

摘要

An object oriented strategy to support the creation of geometric models ispresented. These models are presented as part-whole hierarchies of objects. Creation of new models is done by copying and modifying previously existing models of parts of them. Past models are stored in the system's database and serve as prototypes for the new models. To support the selection of an appropriate prototype the system provides a view on its database presenting an is-a-hierarchy of object type definitions that depends on: the currently available models in the system's database; a functional specification that represents the designer's intentions; and a set of definitions that are used by the system to interpret a functional specification. From the hierarchy the user can either select an object type definition that might serve as a template for a new part or select one of the coast models from which an object type definition originates. Since the is-a hierarchy of object type definitions only exists virtually, is moreover directly controlled by the user and is highly flexible, as well as providing alternative hierarchies presenting alternative views on the system's database, the approach is called retrospective creation of virtual alternative hierarchies.