B-Rep Shape Simplification for Data Conversion between Ship CAD Model and VR Mesh Model

Shipbuilders and suppliers, through their engineering activities, generate an extensive array of shape data for ship structures. However, visualizing the entire shape of a ship on a computer for design optimization or digital evaluation poses a practical challenge. Additionally, it becomes necessary to simplify the boundary representation (B-Rep) shape during data exchange between partners using different computer-aided design (CAD) systems and when creating lightweight shape contents for digital twin implementation. In this paper, we propose a shape simplification method for converting shapes between ship CAD model and virtual reality (VR) mesh model. During the process of reconstructing the ship CAD model into a B-Rep shape, topology decimation is performed to remove unnecessary elements. Furthermore, bounding boxes are created for the sub-primitives of the reconstructed B-Rep shape, and the level of detail for shape simplification is determined by calculating threshold values for these boxes. Sub-primitives with the applied level of detail can be dynamically removed from the assembly model. By utilizing this method, our shape simplification system, ShipCADOptimizer, allows users to review model simplification results in real-time through its simplification functionality. Users can simplify the model while preserving its characteristics by setting appropriate weights and thresholds based on the intended use.