Frontal geometry from sketches of engineering objects: is line labelling necessary?

A tool which can quickly interpret line drawings (with hidden lines removed) of engineering objects as boundary representation CAD models would be of significant benefit in the process of engineering design. Inflation of the drawing to produce a frontal geometry, a geometric realisation of that part of the object visible in the drawing, is an important stage of this process. Previous methods of producing frontal geometries have relied on the technique of line-labelling (labelling edges as convex, concave or occluding). Although restricted subsets of the line-labelling problem have known solutions, reliable methods have not been found for the general line-labelling problem, and traditional methods, when adapted to drawings with non-trihedral junctions, are unacceptably slow. Many other papers assume that line-labelling is an essential step. Here we show this is not necessarily true, and that comparable results can be obtained by a novel alternative approach. Firstly, we consider what o...

• Type: Journal
• Year: 2005
• Where: CAD
• Authors: P. A. C. Varley, Ralph R. Martin, Hiromasa Suzuki
• Keywords: CAD 2005, Frontal Geometry, Line Drawing, Line-labelling Problem, Theoretical Computer Science