Point-oriented Identification for Exchanging Parametric CAD Data

Abstract

As the manufacturing industry has shifted from sequential engineering to concurrent engineering over the past decade, product data sharing has been the center of attention among designers and developers. Product data can be exchanged either using a direct translation approach or through a neutral format like STEP or IGES. The exchange of parametric CAD information was not possible with these neutral formats and to overcome this issue the macro-parametrics approach was proposed [1], [6]. A CAD model is exchanged through an XML-based neutral format of a macro file consisting of modeling commands [7]. A trouble in parametric CAD data exchange has been the consistency of identifiers throughout the process of exchange. To achieve this consistency, entities in a model should be identified persistently and unambiguously. However, the current reference module of TransCAD is based on the topology naming and it suffers from the ambiguity, which arises because of the splitting and merging of topological entities [5], [6]. This problem, commonly referred to as the ambiguity issue of persistent naming, is explained in Fig. 1(a). Additionally, such a neutral format lacks geometric reference that may otherwise be required in a case where target system has a geometry-based identification approach. This problem, referred to as the exchange issue of persistent naming, is explained in Fig. 1(b). These problems increase the time and effort required to build a translator. The aim of this work is to resolve such issues through the integration of geometry and topology into a standard reference module.