A topological entity matching technique for geometric parametric models

Nowadays, many commercial CAD systems support history-based, constraint-based and feature-based modeling. Unfortunately, most systems fail during the reevaluation phase when various kind of topological changes occur. This issue is known as "persistent naming" which refers to the problem of identifying entities in an initial parametric model and matching them in the reevaluated model. We propose a complete framework for identifying and matching any kind of entities based on their underlying topology. The identifying method is based on the invariant structure of each class of form features and on its topological evolution. The matching method compares the initial and the reevaluated topological histories. For each construction step, the matching consists of two phases. In the local phase, two measures of topological similarity are computed between any couple of entities occurring respectively in the reevaluated model and in the initial model. In the global phase, the final matching is defined as a binary relation that maximizes the topological similarity between the matched entities of both models. The naming and matching method has been implemented using the 3D modeling application development platform Open Cascade.