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Multi-level Navigation of a Document Space
Misook Heo
Emile L. Morse
Swantje Willms
Michael B. Spring
email: mxhst,elm2,swan,spring@sis.pitt.edu
http://www.lis.pitt.edu/~elm2/WebNet96.html
Department of Information Science and Telecommunications
University of Pittsburgh
Pittsburgh, PA 15260 USA
Navigation of spaces with more than two dimensions via a two dimensional display using a mouse is difficult, even
when the space and the objects depicted are real-world objects. Navigation becomes more difficult when the space and
the objects have no or minimal natural mappings to physical spaces. While we believe the mechanisms and approach
described here are applicable to any situation in which abstract data is mapped to a physical display, this particular
implementation is explored within the context of CASCADE (Computer Augmented Support for Collaborative
Authoring and Document Editing), a research testbed for exploring the development of agents and tools to support
collaborative authoring of documents [Morse et al. 1996]. Building on the work of [Spring and Jennings 1993] related
to rules for mapping abstract data to virtual spaces, this research explores the use of a set of interrelated tools to assist a
user in navigation of document collections. The research examines the navigational tools in isolation and in
combinations.
The tools may be thought of as a set of maps at different scales which can be used together to aid movement through
complex, abstract document spaces. We begin with the assumption that documents and document components are
objects, these objects are related and have attributes. Each tool looks at one or more of these features. The tools currently
implemented for CASCADE include:
Docuverse. This view depicts objects and selected attributes. It provides an overview of the document space and
may highlight broad areas of interest based on textures that may develop from depiction of selected attributes
such as size, age or other user-selectable document metadata. The docuverse view shows minimal structure, but
depicts general structural features via proximity of objects. Selecting an area of the docuverse would instantiate
the Webview.
Webview. The Webview is a traditional tree browser showing typed relationships between objects and selected
object attributes. Individual documents and links between documents are viewed on a large pannable canvas.
While the prototype currently displays only hierarchical links, future versions will implement mechanisms for
displaying other types of links as well. Selecting a container object in the tree causes the root of the tree to
change -- to the new container. Selecting a leaf node -- a document object, causes the document object to be
displayed, making Landmark tools accessible.
Landmarks. Given a single document, intra-document tools are used to aid navigation. Landmarks within a
document may be chosen to reflect the semantic, structural or other attributes of the document. In the current
implementation, two landmark maps may be appended to a document in CASCADE. Each provides a view of
selected attributes as seen in the displayed part of the document as well as the parts of the document not
displayed.
Preview. Preview provides the reader with previews of the destinations that can be reached from the current
location.
Docuverse
Docuverse represents a large document space by selecting only one or two attributes of the documents in the
space. [Shneiderman 1991] uses a similar technique known as Treemaps which renders both files and directories
as bars. It is sometimes difficult to distinguish files from directories when complex document spaces are depicted