Supporting feature-based parametric modeling by graph rewriting

Sophisticated geometric and semantic models are the basis for many applications in the field of Building Information Modeling. While the requirements in terms of detail, flexibility and conformity on those models and thus on the corresponding modeling tools increase, especially in the case of parametric and procedural modeling, open questions remain regarding the support of the user during the modeling process and the loss of modeling knowledge after finishing a modeling task. Graph Theory can be used when addressing these questions. It can be employed to represent parametric models in a vendor-neutral way and to capture modeling operations by formalizing them in graph rewrite rules. This paper describes the further development and generalization of graph-based model creation for the support of feature-based parametric modeling. We show how such procedural 3D models that are based on two-dimensional sketches can be represented by graphs and how modeling steps can be formalized by using rule-based graph rewriting. This approach enables a user to semi automatically reuse previously formalized modeling tasks, thereby supports and accelerates the modeling process and, additionally, allows the formal definition of expert engineering knowledge for later use and reapplication.