A system for constructing boundary representation solid models from a two-dimensional sketch

This paper describes a system which converts a two-dimensional sketch with hidden lines removed of a single polyhedral object into a boundary representation solid model. The system improves on a previous system by Grimstead (1997) by analysing the sketch for symmetry elements and regularities. It uses the results of this analysis to produce a more plausible topological completion of the hidden parts of the object, and to enforce exact constraints on the geometry of the boundary-representation model.