Open Hypermedia Systems Working Group

Spatial 1 - Scenario

Preliminaries

Authors
Peter J. Nürnberg,
U Aarhus, Denmark
@%AUTHOR2

@%AFFIL2

Updates
Most recent: 15 June 1997 (initial version)


References


• Marshall, C. and Shipman, F. 1995. Spatial hypertext: designing for change. Communications of the ACM 38, 8 (Aug), 88-97.
  
• Nürnberg, P, Leggett, J., and Schneider, E. 1997. As we should have thought. Proceedings of HT 97.
  
• Nürnberg, P, Leggett, J., Schneider, E., and Schnase, J. 1996. HOSS: A new paradigm for computing. Proceedings of HT 96.
  

Other Links


• Analysis
  
• OHS mailing list discussion (when available)

Scenario Description

Background

People faced with the task of organizing pieces of information may be able to use spatial hypertext tools to help them perform this task. Spatial hypertext systems take advantage of people's ability to organize information spatially. In these systems, a piece of information (datum) is represented by an object with certain visual characteristics (shape, color, etc.) that help determine the "kind" of information it is. A given datum may have its visual characteristics changed by a user. Additionally, the image of the datum may contain text and/or other information.

Users are expected to place like data into spatial structures such as stacks, vertical lists, etc. These structures may themselves be placed into structures, and so forth. For example, several vertical lists may be placed side by side, forming a group of lists.

The spatial hypertext system should be able to recognize the spatial structures generated by users and allow users to treat all objects in such a structure as a unit for certain operations, such as movement or deletion. It recognizes these structures by conducting a "spatial parse" the space in which the data reside. An important aspect to the structure generated by a spatial parse is that it is dynamic. Repositioning one or more data may invalidate the results of a previous spatial parse. Furthermore, it is difficult to modify the results of a previous parse to account for data movement. Also, this parse is relatively (time-wise) inexpensive to perform. This means that there is no reason to keep the results of a parse after data are moved. Instead, new structures can be generated by the parser as requested.

Scenario

Casper is using a spatial hypertext system to organize his thoughts about a paper on a natural language problem on which he is working. He is trying to determine what existing systems can address his problem. To this end, he creates a datum for each system in which he is interested. These data are visually represented as blue boxes with the name of the system listed in the box. He organizes these blue boxes into three lists: those systems that do address his problem, those that do not, and those about which he is unsure. He heads each list with a red box datum that contains the name of the list. He is considering 7 systems. 3 of these (foo, bar, and baz) he decides do address his problem. 2 of these (widget and gadget) do not. He does not know about the final 2 (weeble and wobble). His space initially looks like this:

Figure 1. The initial space.

The spatial hypertext system he is using allows hierarchic click selection. That is, the first click on a datum selects it for a further operation, such as movement or deletion. A second click on an already selected datum additionally selects all of the datum's "neighbors" in the next highest spatial structure. Such selection of neighbors in ever higher-level structures can continue until all neighbor's in the highest level structure in which the original datum is located are selected. Clicking in "empty space" (space in which no datum resides) unselects all selected data.

Casper decides after further reading that the weeble and wobble system do not address his problem. Casper selects the weeble object. He then clicks again to select all objects in the structure in which weeble is embedded. The spatial parser recognizes that there is a list of blue objects in which weeble is embedded, and selects all other objects in that structure. In this case, only one other datum is in this structure, that being the wobble datum. With these objects selected, his space looks like this:


Figure 2. The space with the first-level neighbors of weeble selected.

He then moves these objects into the Don't column. He then deletes the Unsure list header. His screen then looks like this:


Figure 3. The space after merging the Don't and Unsure lists.

Later, Casper decides he doesn't want to discuss systems that don't address his problem in his paper. He again selects weeble. Then he clicks again, which selects all objects in the list of blue objects in which weeble is located. In this case, the widget, gadget, and wobble data are all selected. He clicks again, and the Don't datum is added, since it belongs to the "red-headed list of blue data" structure. With these objects selected, his space looks like this:


Figure 4. The space with the second-level neighbors of weeble selected.

He then deletes all of these objects and continues his writing task.