Designing solid objects using interactive sketch interpretation

Before the introduction of Computer Aided Design and solid modelling systems, designers had developed a set of techniques for designing solid objects by sketching their ideas on pencil and paper and refining them into workable designs. Unfortunately, these techniques are different from those for designing objects using a solid modeler. Not only does this waste avast reserve of talent and experience (people typically start drawing from the moment they can hold a crayon), but it also has a more fundamental problem: designers can use their intuition more effectively when sketching than they can when using a solid modeler. Viking is a solid modelling system whose user-interface is based on interactive sketch interpretation. Interactive sketch interpretation lets the designer create a line-drawing of a de- sired object while Viking generates a three-dimensional ob- ject description. This description is consistent with both the designer's line-drawing, and a set of geometric constraints either derived from the line-drawing or placed by the de- signer. Viking's object descriptions are fully compatible with the object descriptions used by traditional solid modelers. As a result, interactive sketch interpretation can be used with traditional solid modelling techniques, combining the advantages of both sketching and solid modelling.