A mechanism for persistently naming topological entities in history-based parametric solid models

One of the fundamental problems in history-based parametric solid modelling systems is to identify topological entities (faces, edges, vertices) of solid models in such a way that the same entities can still be identified after the models have been re-evaluated from the sequential history of modelling steps. The Topological ID System, presented in this paper, systematically assigns IDs (names, labels) to topological entities in solid models. When the history of modelling steps is edited and then automatically re-evaluated to produce a new version of the solid model, the IDs of topological entities in the old version of the solid model are mapped to IDs of the corresponding topological entities in the new version of the solid model. This mapping defines the correspondence between topological entities in both models. Copyright (C) 1996 Elsevier Science Ltd