Dissertation Abstract

Title: 		 Tabula Rasa: A Multi-scale User Interface System 
Author: 		 David Fox 
Advisor: 		 Ken Perlin

This dissertation develops the concept of a zoomable user interface and identifies the design elements which are important to its viability as a successor to the desktop style of interface. The implementation of an example system named Tabula Rasa is described, along with the design and implementation of some sample applications for Tabula Rasa. We show how programming techniques such as delegation and multi-methods can be used to solve certain problems that arise in the implementation of Tabula Rasa, and in the implementation of Tabula Rasa applications.

Over the past thirty years the desktop or WIMP (Windows, Icons, Menus, Pointer) user interface has made the computer into a tool that allows non-specialists to get a variety of tasks done. In recent years, however, the applications available under this interface have become larger and more unwieldy, taking into themselves more and more marginally related functionality. Any inter-operability between applications must be explicitly designed in.

The Zoomable User Interface (ZUI) is a relatively new metaphor designed as a successor to the desktop interface. It is inspired by the Pad system, which is based on a zoomable surface of unlimited resolution. Just as the desktop interface has a set of essential elements, a ZUI has a set of elements each of which is vital to the whole. These include

• a zoomable imaging model,
• a persistent virtual geography for data objects,
• semantic zooming to optimize the utility of screen space,
• work-through interfaces for application objects,
• a constraint system for ensuring the consistency of the interface elements.

These basic elements combine to produce an environment that takes advantage of the user's spatial memory to create a more expansive and dynamic working environment, as well as encouraging finer grained applications that automatically inter-operate with various types of data objects and applications.

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