People draw diagrams and sketch to explore ideas, understand problems, generate alternatives, and communicate. However, today's menu and text based human-computer interfaces do not take advantage of this commonly used modality. The Back of an Envelope project aims to support freehand drawing as an interface to knowledge based design tools. It employs advances in gesture recognition, interpretation of visual languages, and pen based computing, and explores how to combine these technologies to build drawing interfaces for end user applications. The Back of an Envelope has three specific objectives: develop a framework for using freehand drawing to communicate with computer-based design tools, construct a working prototype that links a drawing interface with design tools, and assess the prototype's performance in design studios and classroom settings. The project also aims to elucidate roles that graphical communication plays in problem-solving and design. The project's significance is that it expands the range of modalities available to end users, enhancing traditional text and menu interfaces with freehand drawing. This enables designers to employ computer aided design tools earlier in a design process, when they are sketching and making diagrams. Besides computer aided design, the Back of an Envelope interface framework can be employed in other problem solving applications.
