Two papers for Jacques Haus' talk on 03/06/96
This technique answers a specific problem: how to depict entire information spaces, knowing that the limited size of the display screen makes creating global view difficult? A solution is needed, which 1) displays what the user wants to see and 2) allows the user to focus quickly on areas of interest. A good navigation technique is believed to be an important part of the solution. Some alternatives exist:
- Detail-only browsers give a good display of the user wants to see, but the selection of an area of interest is limited (it uses a scrollbar, which gives only a relative position, no information about context).
- Fish-eye (focus + context) views, including perspective wall, document lens, table lens,... For some information, it is very effective, but contextual information may become really distorted or too small, and it is expensive to draw.
- Multiple views: detail and global views are separated. Some navigation technique allows to select the local view location in the global view. The solution developed here is based on this technique.
The use of information mural is a way to provide a global view of an information space. It provides a reduced representation that fits entirely within one display window. Instead of rounding the position of information elements to the nearest pixel or using a form of abstraction to compress the representation, anti-aliasing techniques and grey-scale shading are used to create a miniature version of the entire dataset.
Execution murals provide a focus area, a global view and navigation capabilities. It is demonstrated for the visualization of traces of object-oriented programs. The focus area display messages exchanged between objects in different classes (classes are positioned along the vertical axis and time is represented by the horizontal axis. A global view (information mural) displays the whole set of messages. It includes a navigation rectangle which indicates where the focus area fits within the entire execution. This view also serves as a navigational widget for the focus area, providing panning and zooming capabilities (use of information mural as navigation tool).
For a tool to be effective, users must be able to interact with it. In this example described above, the execution mural allows for:
investigation of global patterns in the execution.
focus on the details of a particular execution phase.
examination of the role of different messages
focus on relationship between particular classes.
Some other applications include document editing, data and image visualization.
It is a combination of 3 tools supporting two complementary processes in a single environment: design as a constructive process of selecting and arranging graphical elements, and design as a process of browsing and customizing previous cases. One of the objective is to face limitations of current graphics packages:
- Provide integrative displays for viewing the relations among several data attributes or data sets (most packages do not allow to lay-out multiple graphs in a coordinated way).
- Reduce the complexity of the interface.
- If you provide the ability to create new integrative display, you need to provide design guidance as well (considerable graphics expertise is currently required from users in packages where little guidance is provided). The objective is to use automatic mechanism to support users, not to replace them.
The SAGE system is made of multiple design tools:
- SageBrush is a design tool interface: users specify graphics by constructing sketches from a palette of primitives and/or partial design. Users interact with SageBrush to create sketches (partial or complete), which are translated into design directives that SAGE can understand. They can compose graphical queries and customize graphics found by SageBook. It is also possible to define layout spaces, enabling users to specify the relative positions of prototypes in respect to each other.
- SageBook is an interface for browsing and retrieving previously created pictures (search and reuse of prior cases with customizing is a common process). In addition to storage in user-defined locations, pictures can be browsed by two types of picture content: graphical elements and data (based on exact match or partial overlap).
- SAGE is an automatic presentation system. With a characterization of data and a user's data viewing goals, design operations include selecting techniques based on expressiveness and effectiveness criteria, and composing and laying out graphics appropriate to data and goals. Use of knowledge allows to automatically design or to complete partially specified designs.
Future problems to address include the display of large data sets, and graphical techniques such as animation and 3D.
haus@cc.gatech.edu