An Approach to Naming and Identifying Topological Entities
Zheng Chen · Chinese Journal of Computers · 2001
One of the fundamental issues in history-based parametric feature modeling systems is to correctly identify topological entities by name matching during the re-evaluation of the model. In this paper, we propose a new approach to name matching of topological entities. The approach is based on two new concepts, i.e. the affect features and affect faces of topological entities which refer to the features and faces used in generating the topological entities. We determine if a topological entity in the new version of the solid model is identical to its corresponding topological entity in the old version of the solid model by finally checking whether there is sub-set relationship between the affect feature sets and affect face sets of the two topological entities. To correctly identify topological entities, a new naming schema to topological entities is also proposed. The usual topological entities are named by using the ID of the feature it belongs to, and its index in the B-rep of the feature, etc. For the referenced topological entity, the local topological information is added into the name. The local topological information consists of the adjacent faces of the topological entity and the in-out relationship among them. The main characteristic of the proposed approach is that the topological element is identified by the information of features and feature faces, which have effect on the generation and change of the topological element. The proposed approach has been implemented in our prototype feature modeling system ZDFMS. The advantage of the proposed approach is that the identified topological entities are more reasonable in respect to the design intent.