Within a shipyard, many designers each having their own design objective cooperate in a complex design situation where a variety of software tools run on different hardware platforms. The exchange of design data models among these heterogeneous CAD systems is a difficult task because the involved systems have different data structures optimized for their own functions. CAD models are represented by different schemes such as 2D graphic entities, 3D wireframe, 3D surface model, and solid B-Rep/CSG model. A data exchange between these schemes usually requires topological modifications of CAD data This paper presents a strategy of CAD data enhancement for the purpose of data exchange that includes topological changes of geometric models. As a product model, a midship schema has been defined based on ship building blocks and STEP AP203. In order to represent systematically a product model and to realize an open architecture framework, STEP methodology is utilized. Shipbuilding features are defined in the midship schema and these features are recognized from 2D drawings during the data enhancement processes. Its geometric data is enhanced through ACIS non-manifold model into a data set valuable to downstream systems such as a FEM solver or a detail design system. Geometric enhancement requires a lot of low-level geometric operation, and during the process there may exist incomplete geometric information. Non-manifold model supports various geometric schemes have more flexibility for creation of 3D model.
