Transparency is a technique that can be used to draw the user's attention to important areas of information by taking advantage of human visual perception. Information can be emphasized by using techniques which simulate depth. This effect is achieved by heightening the contrast between the information being emphasized and "background" information, either by blurring the background or by using transparency to fade the background.

In a three-dimensional visualization of a timeline which contains perhaps thousands of graphical objects such as text and images, continuous gradual transitions between transparency and opacity and can be used to visually distinguish relevant information while retaining context. For example, a user might want to search a timeline for details of a specific event, such as a particular battle during World War II. Transparency could be used to focus attention on the specific details of the battle of interest, while the general context of World War II, though de-emphasized, would still be visible in the background. Smooth visual transitions between transparency and opacity provide the access to detailed information while simultaneously placing the battle in the correct historical context.

The Visible Language Workshop of the MIT Media Laboratory has produced groundbreaking design research regarding dynamic design and three-dimensional information visualization. This work draws heavily from the lifelong work of the late Professor Muriel Cooper, a pioneer of design for computational media [Cooper 1989]; Grace Colby and Laura Scholl's research into the use of transparency in dynamic information design (Figure 7)[Colby 1992]; Muriel Cooper and David Small's Information Landscapes, an interactive visualization of an abstract information space [Abrams 1994]; Suguru Ishizaki and David Small's Typographic Space, an early exploration into the use of typography in a three-dimensional virtual space [Small 1994]; Ishantha Lokuge and Suguru Ishizaki's GeoSpace project, which takes advantage of size and transparency in visualizing personalized geographical information [Lokuge 1995]; Lisa Strausfeld's Financial Viewpoints, which explores using point-of-view in visualizing abstract financial data in three dimensions [Strausfeld 1995]; Earl Rennison's Galaxy of News, a browser which uses animation and scale to allow the user to access a news database [Rennison 1995]; and unpublished work by my colleagues Yin Yin Wong and Suguru Ishizaki exploring issues of designing in space and time [Wong 1995; Ishizaki 1996].