Interaction techniques for solid modeling with a 3D input device

Modeling in three dimensional (3D) space is an important field in computer-aided design (CAD) and computer graphics. The use of computers in the design of 3D models has been fruitful, yet largely confined to the late stages of the design process, namely, analysis, simulation, drafting, and documentation. The early stage--that of conceptual design, or sketching--has so far hardly been touched. The user interfaces of most CAD systems impose a limit on the speed that a designer can translate his or her ideas into a computer model. As a result, designers usually prefer a more facile medium when sketching. In most cases, this means sketching with pencil on paper. This thesis originated from the vision that CAD technologies can be extended into the sketching stage, to become a tool covering the entire design process. We focused on the ergonomics of interface design, since several problems in this area were identified as major limiting factors. New interaction techniques were developed to provide the designer with easy and flexible ways of creating and manipulating 3D shapes. With a 3D input device and a fast graphics workstation, an environment was developed in which a designer can directly interact with 3D shapes using an array of new interaction techniques. In particular, a non-immersive 3D interface style for the modeling system was developed allowing a smooth transition between sketching and later design stages, and the integration of existing 2D interaction techniques. New interaction techniques at various levels were developed. First, we designed basic interface elements such as 3D menus, selectors, and dials. We then developed techniques for the creation, placement and reshaping of 3D shapes. We also developed inspection tools for 3D shapes. These new interaction techniques are integrated into a prototype solid modeling system (JDCAD) for study and evaluation. We informally evaluated the overall effectiveness of the new interface style and interaction techniques by first comparing our prototype system JDCAD with a commercial CAD system and then with hand sketching. It was shown that it took less time for a designer to create test objects in JDCAD than in the commercial CAD system. We also showed that for an expert user, the sketching speed with JDCAD is comparable with hand sketching using pencil and paper. These encouraging results demonstrate the potential of the new interaction techniques, and indicate a significant progress in extending the use of CAD systems into the sketching stage of 3D modeling.