SIGMA

Scalable Interfaces for Geometry and Mesh based Applications

Sealing Faceted CAD Geometry

Posted by on Jun 24, 2014 in Meshkit

Facet based models are a useful format for file transfer, mesh generation, and efficient geometric computation. Solid modeling engines typically facet each surface independently. It is likely that the faceted boundaries of neighboring surfaces are not the same, especially for non-manifold models. Gaps, overlaps, and discontinuous topology can occur between surfaces. This is problematic for meshing, ray tracing, and other applications that expect a watertight faceting.

This tool uses MOAB to read facet based models produced by a solid modeling engine in CGM. It is assumed that the feature size is greater than the facet tolerance, and the facet tolerance is greater than the merge tolerance. Faceted surfaces are skinned to resolve their boundary. Bounding edges of each faceted surface are assembled into loops. Loops are cut into arcs that correspond to faceted curves, using geometric vertices. Each arc is then sealed to its corresponding curve by using node-node and node-edge contraction. The result is a watertight model in which adjacent surfaces share the same faceted edges.

Smith, Brandon M., Timothy J. Tautges, and Paul PH Wilson. “Sealing faceted surfaces to achieve watertight CAD models.” Proceedings of the 19th International Meshing Roundtable. Springer Berlin Heidelberg, 2010. 177-194.


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