A User Interface Model and Tools for Geometric Design

Poor user interfaces discourage potential users from effectively utilizing the design capabilities of geometric modeling systems. Because of the complex nature of the underlying representations in such systems, a well structured user interface model, as well as useful and intuitive design tools, are necessary. As a result, this thesis addresses two areas. First, a general software architecture for graphical user interfaces is presented that supports and encourages experimentation and research into new interactive design techniques. The architecture has been designed for use in a distributed environment and is based on the idea of providing appropriate visual and interactive abstractions for each design operation. The model is presented here in the framework of a geometric design system, but may be applicable to other areas as well. Secondly, several interactive design tools are explored. These include algorithms for sketching nonuniform rational B-spline curves, and interactive graphical tool based on pattern matching.