EVALUATING THE COMPLEXITY OF CAD MODELS IN EDUCATION AND PRACTICE PAUL MURTY, SCOTT CHASE, and JOSEPH NAPPA University of Sydney, Department of Architectural & Design Science Abstract. When educators or students estimate the complexity of proposed CAD projects, in order to judge feasibility, two conceptions of complexity may be considered. The first, design complexity, based on visible features of the object to be modelled, is the easier to assess beforehand, but is not very reliable. The second, CAD complexity, based on the actual CAD embodiment of the design, is suggested as potentially a more useful guide, in spite of evident difficulties with assessment in advance. Clearer articulation of this under utilised concept is proposed for both educational and more general reasons, and this becomes the focus of the paper. 1. Introduction A frequent culmination of computer aided design (CAD) teaching is the self-directed project, for which a student produces a CAD drawing or model. Each student is required to select a suitable design, and then to develop and implement strategies to produce and display their model. During discussions with students, on choice of project and their general approach, matters of complexity inevitably enter discussions. For any individual there is an optimal range of complexity. A too modest project may fail to challenge and extend, if the potential to extend the individual’s technical knowledge is not exploited. An over complex undertaking, if not recognised and corrected early, may consume many hours of effort, much of it fruitless, leaving the individual frustrated, demoralised and mistrustful of CAD technology. Two interpretations of complexity are often discussed at the outset, namely design complexity, based on the appearance of the object to be modelled, and CAD complexity, based on the actual CAD embodiment of the design. Design complexity is the more popular indicator of manual drafting task magnitude, because it is visible before work commences. But appearances can be misleading, especially in CAD production, where magnitude of a task is highly dependent upon interpretation, what the designer chooses to model and chosen methods of representation. Superficial aspects of drawings and photo-