A Direct Manipulation Environment for Conceptual Design of Three Dimensional Objects

The conceptual design of a three-dimensional model can be regarded as a cyclic process in which a global scheme is gradually refined into a detailed specification of components. The system presented in this chapter demonstrates how an object-oriented approach in combination with an interactive graphical environment facilitates the elaboration of a design concept during the different stages of the design process. A model is described as a part-whole hierarchy in which components are represented as interrelated graphical objects with an internal representation. Objects can be grouped bottom-up into more complex objects, or alternatively, their internal representation can be decomposed top-down into other objects. An interactive graphical interface allows the designer to view and edit both the geometric and the hierarchical organization of the model by direct manipulation.