Distributed display environments

The term Distributed Display Environment (DDE) compactly describes computer systems that present output to more than one physical display. Often DDEs allow attached input devices to treat the displays as a contiguous surface but this is not necessarily a requirement. Examples include multiple-monitor desktop systems, rooms with networked projectors and displays showing information on any physical surface, or even campusor city-wide connected information display systems. In any of these physical configurations, there can be a single user, collaborative user groups, or multiple users in non-collaborative situations. Although much previous HCI research includes implicit or explicit assumptions that a computer system has at most one physical display attached, recent research has recognized that a computer system can have more than one physical display and that people frequently use multiple displays much differently than singledisplay systems. Research methods and foci have varied, but findings suggest that (1) continuing to define the relevant aspects of DDEs is worthwhile due to obvious and quantifiable benefits of these environments and (2) there are important aspects of interfaces that have been ignored in the past because of the assumption of a single-display output model. In April 2005 at the CHI conference in Portland, 16 researchers gathered at the Distributed Display Environment workshop to discuss the future of the field. The organizers structured the workshop to encourage discussion of future directions of the field. In particular, only the first 90 minutes covered participants’ past work in the area while the remaining five hours were devoted to discussing four specific goals: (1) determine promising areas for new interaction research, (2) detail the aspects of incorporating passive information display into interfaces, (3) determining what to evaluate and how to evaluate it, and (4) outline broader implications of the increasing ubiquity of DDEs to HCI research. While the group discussion did address each of these goals in some way, the researchers became more interested in crafting a first draft of a framework of the many factors that DDE research involves. This interest seems to primarily arise from the wide variety of work that was presented by each researcher in those first 90 minutes; there was a clear desire to build a common language to facilitate a shared understanding of each other’s work. As a result, the group devoted most of the time to brainstorming and generating an initial framework, with frequent pauses for discussion when suggested framework elements needed deeper interpretation or explanation. We now share a selection of framework elements that directly address the multi-display system properties. Note that some very interesting aspects of the framework do not involve properties of the display system at all, such as whether it supports multiple users simultaneously or only a single user at one time, but since these are thoroughly discussed in other forums we leave them aside in this brief article. One element of the framework is the degree to which an interface supports replication, i.e. showing the same information or UI components on multiple displays simultaneously. The notion that replication can be useful is beginning to appear more frequently and for a variety of situations, such as for personal use in single-user multiple-monitor interface situations [3], mixed use of personal displays and group-