A new sketch partitioning and analysis techniques

This paper presents a new concept for reconstructing a 3D object from a construction design sketch under an orthogonal isometric project. In general, for a mechanical part, it can be constructed from a base geometry and then incrementally add or cut other basic constructive elements. During a conceptual design process, designers work through this basic form construction process with freehand drawing, a construction sketch can be received progressively with principal and construction lines. This construction sketch contains information about a valid construction process with related elements, which in turn can support CSG-based solid modeling. The construction sketch can be partitioned into several feature drawing; each feature drawing can be topologically represented a feature graph, and easily recognized as a projection of a corresponding 3D constructive element. While the relationship between two feature graphs gives information to construction methods such as add (Boolean Union) or cut (Boolean Subtraction). From these information, reconstructing a valid 3D object from an construction sketch can be achieved interactively, realizing the “What You Draw is What You Get” design fashion without pre-defined gestures. This paper details construction sketch partitioning and analysis techniques for 3D reconstruction.