2.2 Terms related to Presentation Systems

In this section we introduce some basic terms to characterize presentation systems.

presentation system

refers to the class of computer systems which are designed for the purpose of presenting information to users. Essentially, presentation systems perform information transformation processes. Depending on the nature and complexity of the transformation, one may further introduce the intuitively motivated distinction between systems for the mere display of presentations, and systems performing presentation generation. Our focus is on generative systems, i.e., systems whose behavior cannot be described by a simple one-to-one mapping of input units to media objects which will be displayed to the user.

presentation goals

which have to be achieved by the system, possibly accompanied by a set of presentation commands or presentation constraints (such as ``the presentation must not exceed one page'') affecting the presentation process, constitute the primary input to a generative presentation system. Both goals and commands are assumed to be formulated outside the presentation system, i.e., by the user, or by an external system, or by a superordinate component in case the presentation system is a part of a larger system. Goals and commands include a high level reference to collections of data together with the purpose (or the intention) for communicating information.

application data/knowledge

provides the semantic grounding of each presentation which may be generated by a system. As with presentation goals and commands, it is assumed that application data/knowledge is part of the input to a presentation system (see also the right most column of Fig. 2). In other words, there must be an external source (e.g., an application system or a database) that makes available to the presentation system the application data necessary for achieving posted goals.

multimedia presentation system

is a presentation system that employs multiple media to present information to the user. Again, the focus of the reference model is on generative systems, i.e., systems which transform given presentation goals as triggering inputs into multimedia presentations as output.

intelligent multimedia presentation systems

are essentially knowledge-based systems, i.e., systems with the distinguishing characteristics that there is a clear separation of a declarative knowledge representation - usually called knowledge base- and application targeted computation processes which exploit the knowledge base. In case of an IMMPS the knowledge will be exploited in order to draw appropriate design decisions.

There are a few further terms which will be used to characterize the internal processes which a presentation system may perform.

content selection

refers to the process of selecting some content (i.e., application data/knowledge) in order to satisfy presentation goals. Content selection may also be regarded as a filtering process.

media/modality allocation

refers to the process of deciding which presentation medium/modality or media/modalities combination to choose for achieving a certain presentation goal together with selected content. On can further distinguish between mapping types of data or content onto types of media/modalities (e.g., database entries onto tables versus maps) versus matching properties of information (e.g. quantitative versus qualitative, fixed versus varying) with properties of media/modalities (e.g., persistent or not; static versus dynamic, 2D vs. 3D, having a geospatial dimension).

media/modality-specific encoding

refers to the process of generating media objects conveying a certain message in a certain media/modalities combination. For example, a presentation system may comprise dedicated generation modules for encoding relational data sets either by formatted tables, charts, or pure text.