Sealing Faceted Surfaces to Achieve Watertight CAD Models

Solid modeling engines are capable of faceting CAD models but may facet each face independent of adjacent faces. Regions of the resulting model have gaps between faces of their boundaries. An algorithm is described to seal faceted CAD models such that the boundary of neighboring faces has the same discretization along their shared edges. The algorithm works by sealing skin edges of geometric face faceting to geometric model edge facets, using vertex-vertex and vertex-edge contraction. Ten intricate CAD models of moderate to high complexity are tested with a range of facet tolerances. The algorithm succeeds in creating watertight models in most cases, with failures only at extreme values of facet tolerance and/or in the presence of geometric features which are outside the normal features encountered in most models.