Fast Surface Meshing on Imperfect CAD Models

CAD model repair is often a necessary precursor to mesh generation, due primarily to the inconsistencies between the tolerances used by the designer and the tolerances required by the analyst. This paper presents a method for meshing directly on imperfect CAD models without needing to repair the model. This is done via a hierarchical grid topology structure that defines a surface grid by a mesh and by a series of curves defining its boundaries. Curve boundaries are iteratively split and merged based on user-set tolerances, allowing the surfaces to become topologically watertight. Interactive methods to aid in degenerate cases are also described. Finally, ongoing work for automatic formation of surfaces meshes spanning multiple surfaces is described. This procedure involves agglomeration of surface meshes based on connectivity and bending angle, followed by decimation of surface triangles to remove artifacts from irregularly-shaped CAD surfaces.