Despite huge investments by vendors and users, CAD productivity remains disappointing. Our analysis of real-world CAD usage shows that even after many years of experience, users tend to use suboptimal strategies to perform complex CAD tasks. Additionally, some of these strategies have a marked resemblance to manual drafting techniques. Although this phenomenon has been previously reported, this paper explores explanations for its causes and persistence. We argue that the strategic knowledge to use CAD effectively is neither defined nor explicitly taught. In the absence of a well-formed strategy, users often develop a synthetic mental model of CAD containing a mixture of manual and CAD methods. As these suboptimal strategies do not necessarily prevent users from producing clean, accurate drawings, the inefficiencies tend to remain unrecognized and users have little motivation to develop better strategies. To reverse this situation we recommend that the strategic knowledge to use CAD effectively should be made explicit and provided early in training. We use our analysis to begin the process of making this strategic knowledge explicit. We conclude by discussing the ramifications of this research in training as well as in the development of future computer aids for drawing and design.

This paper reviews two projects undertaken in a CAD programming course that demonstrate to the students how programs could be developed to investigate possible architectural forms. The projects highlight a very sequential approach to form investigation in using both common geometries and the introduction of randomness to control design rules. This approach stressed the development of rules and evaluating their results as a method to determine the next step to investigate. Equal importance was placed on the anticipated, as well as, the unexpected. INTRODUCTION The College of Architecture has already in place for a number of years a series of courses that cover 2D and 3D CAD, image processing, composition and multimedia, and animation. With the increased use of computers in the studio and the advanced level of CAD use by students who have taken the above series of courses, a number of students requested that a CAD programming course be developed. The overall intention the course was t...

This paper reports on an ongoing research project on an "nonpencil" approach in generating architectural forms using nontraditional geometries. Space curves are investigated to determine nodal points in 3D space, which are then interpreted into common architectural elements. The nodal points are used in a variety of ways to generate walls, columns, floors, and volumes. The determination of forms is totally under program control without any manual interpretation or intervention. A set of simple rules is used to investigate potential forms. The project further extents my continuing interest in developing software as a method of investigating design concepts and generate the unexpected.