The Right Tool at the Right Time -- Investigation of Freehand Drawing as an Interface to Knowledge Based Design Tools
Designers use different symbols and configurations in their drawings to explore alternatives and to communicate with each other. For example, when thinking about spatial arrangements, they draw bubble diagrams; when thinking about natural lighting, they draw a sun symbol and light rays. Given the connection between drawings and thinking, one should be able to infer design intentions from a drawing and ultimately use such inferences to program a computer to understand our drawings. This dissertation reports findings from empirical studies on drawings and explores the possibility of using the computer to automatically infer designer's concerns from the drawings a designer makes. This dissertation consists of three parts: 1) a literature review of design studies, cognitive studies of drawing and computational sketch systems, and a set of pilot projects; 2) empirical studies of diagramming design intentions and a design drawing experiment; and 3) the implementation of a prototype system called Right-Tool-Right-Time. The main goal is to find out what is in design drawings that a computer program should be able to recognize and support. Experiments were conducted to study the relation between drawing conventions and the design tasks with which they are associated. It was found from the experiments that designers use certain symbols and configurations when thinking about certain design concerns. When thinking about allocating objects or spaces with a required dimension, designers wrote down numbers beside the drawing to reason about size and to calculate dimensions. When thinking about visual analysis, designers drew sight lines from a view point on a floor plan. Based on the recognition that it is possible to associate symbols and spatial arrangements in a drawing with a designer's intention, or task context, the second goal is to find out whether a computer can be programmed to recognize these drawing conventions. Given an inferred intention and context, a program should be able to activate appropriate design tools automatically. For example, concerns about visual analysis can activate a visual simulation program, and number calculations can activate a calculator. The Right-Tool-Right-Time prototype program demonstrates how a freehand sketching system that infers intentions would support the automatic activation of different design tools based on a designers' drawing acts.