The Back of an Envelope project demonstrates how a calligraphic interface (one that employs a pen or stylus to input freehand drawing marks) can be used in a wide variety of domains, from databases to simulation programs, to 3D modeling, from mostly symbolic diagrams to freeform sketches. The wide variety of drawing types and domains calls for a diverse range of approaches. We describe some of the functionality of our systems, including contextual recognition of symbols and con”gurations and emergent shape recognition, and some of the calligraphic interfaces we’ve built. ( 2000 Elsevier Science Ltd. All rights reserved.

Keywords: Design; Diagramming; Freehand sketching; Human}computer interface; Knowledge-based design systems; Recognition