An Information-Model for Presentation Generation

Transcription

1 An Information-Model for Presentation Generation Katja Otto, Heidrun Schumann University of Rostock, Computer Science Department D Rostock Germany {kotto, schumann}@informatik.uni-rostock.de Abstract: The effective and appropriate presentation of information is an essential task in our information society. The better the information can be described, the better it can be presented. This paper presents an approach for modelling information and its characteristics and describes, how it can be used for presentation generation. On the base of this approach we implemented a flexible framework for multimedia presentation generation. 1 Introduction A useful way for the presentation of information are multimedia-systems. They use different media for different messages and therefore they offer a great functionality. On the other hand, the presentation generation as well as the definition of interaction structure has to be done before using the system. This leads to high effort for development, low level of flexibility (e.g., varying users or information) and no possibility to integrate visualisation techniques. In contrast to it Intelligent Multimedia Systems (IMMPS) generate multimedia presentations on the fly responding to questions asked by an user. During this generation several influencing factors are considered (e.g., characteristics of the user, the application and the resources).therefore this systems realise a very flexible framework. Starting point of presentation generation in IMMPS is a question asked by an user. Based on this question information, which shall be presented, is selected. Depending on the selected information, different presentation techniques are more or less suitable. The better the information can be described the more appropriate and effective it can be presented. Nowadays IMMPS are special-purpose-systems, which manage special information with known characteristics only. In [Bord97] a general reference model for IMMPS is proposed, but a model of underlying information is not described. The goal of this paper is the development of an information model which is general and appropriate for flexible presentation generation. After a short survey on related work (chapter 2) a formal description as base for the information model is proposed (chapter 3). To refine the description of information we developed an object oriented paradigm which takes into consideration many characteristics of information. Therefore it is especially suitable for effective presentation generation (chapter 4). Finally a case study shows the useful application of the developed ideas in the field of ecology (chapter 5).

2 2 Related Work Today there is no common-sense definition of the concept information except Shannons approach [Shann76]. Shannons definition of information is a quantitative measure but does not allow qualitative statements, e.g. how useful is an information in a given situation. Therefore this definition is not suitable for modelling information in a presentation system. Instead of a general definition, there are many different definitions depending on the application background (cf., e.g., [Gersh94], [Behme93], [Roth93], [André93] and [Wendt91]). The description of information by Wendt [Wendt91] is treated as a proper basis for the development of an information model. Wendt describes information as something someone could know. As primary aspects of the world objects, attributes and relations are mentioned. As shown in figure 1, objects can be distinguished depending on whether they belong to the inner world or outer world and whether they are abstract ore concrete. According to this classification you can consider things, processes and terms as basic types of objects. objects in the outer world in the inner world concrete abstract things processes terms Figure 1: Objects according to [Wend91] Between objects exist several relations, for instance a consists-of-relation or the belongs-torelation. Additionally there can be defined relations between objects which result from the comparison of attribute values. An appropriate modelling of information for presentation generation also includes the description of different characteristics of information. This problem is a current topic. In the field of problem-oriented visualisation there exist different approaches to describe the characteristics of a data set as starting point of its suitable visualisation (e.g. [Mack86] and [Lang95]). The description of the characteristics of information is more complex as the description of data sets. Furthermore we are not restricted to the use of visualisation techniques rather we want to use different media. Several characteristics of information relevant for presentation generation are described in [Andr93], [Roth93], [Aren93] and [Zhou96]. But all of them focus on special details only. 3 Modelling and Characterisation of Information Starting with a formal description of relevant concepts (see [Wüns97]) we want to use the object oriented approach to refine the definition of information and its characteristics.

3 3.1 A formal problem description We want to use the term information object as a necessary abstraction of information representing data in an information processing system. An information object is a concrete object, which may be part of another information object. The information set IM is a discrete set of information objects: IM = {IO 1,..., IO n } i j: IO i = IO j with i j, n,i,j N The information structure IS is a relation, which defines the connections between the information objects. IS IM IM The information space IR is now defined by an information set and an information structure: IR = {IM, IS} with IM 1 and IS 0 Information objects are characterised by attributes. An attribute set AM is the set of all attributes A i of a set of information objects. AM = attr({io 1,..., IO k }) k N where attr({io 1,..., IO k }) = {A 1,..., A n } i j: A i = A j with i j, i,j,k,n N provides all attributes of a set of information objects. 3.2 An object-oriented information model The formal description introduced above clarifies main concepts, but the considered characteristics are not enough for presentation generation. Therefore we want to use an object oriented paradigm to refine the definitions. We interpret any information object as an object in the sense of object oriented modelling. We introduce several classes to summarise objects with equal characteristics and establish a class hierarchy to describe dependencies and connections between information objects. The development of the class hierarchy is based on the information description by Wendt (see chapter 2). We define things, processes and terms as basic classes of the upper class information object to distinguish the elements of the information set IM. To describe the elements of the information structure IS we introduce the relation object-object-relation. Because object-object-relations are not symmetrical we introduce the terms starting object and relation object to distinguish the meaning of information objects in the relation. The information space IR can be described as detailed as necessary by defining further subclasses. While the classification term thing process can be treated as general, the further refinement of classes is application dependent. Figure 2 shows an example for a possible class-refinement for an application concerning libraries.

4 information object abstract name term thing process starting object relation object sub-process book titel ISBN author price colour person full_name age address_town address_street address_number starting object relation object knows duration quality object-objectrelation librarian salary reader since YearWarning NumWarnings CurrWarning starting object likes_reading relation object Figure 2: An information model in the field of libraries 3.3 Characteristics of information space Now we want to discuss the question, what characteristics of the information space are relevant for presentation generation. Let us consider the properties of the elements of the information set IM and the attribute set AM Characteristics of information objects For presenting information objects the following characteristics can be considered as important: The class of the information object specifies the basic class of the information model, to which the information object belongs. That means, we only want to distinguish between the classes thing, process and term because these classes can be presented equally. Usually you present processes by video or animation, for example. The importance of information objects determines, in which amount the attention of the user should be focused on the information object. Here we can use a classification, for instance a three-step-classification (very important, important, informative). The visibility of information objects says, whether an information object is visible in real world by the human visual system or not. Table 1 summarises the described characteristics. characteristic class importance values thing, process, term very important, important, informative

5 visibility yes, no Table 1: Characteristics of information objects Characteristics of attributes Every information object is described by several attributes, which define a subset of the attribute set AM. Furthermore we want to permit the definition of attributes of object-objectrelations. It is possible that the user wants to get the presentation of information objects (or object-object-relations) together with their attributes (for example as response to the question Where do the readers live? ). But you can also imagine that attribute values should be presented without information objects (for example the question How old is Michael? does not require the presentation of Michael but of his age only). For both cases we need a proper description of attributes for presentation generation. The importance and the visibility of attributes can influence the choice of proper media for presentation, as already has been described for information objects. Furthermore, for an effective presentation of attributes we have to integrate several visualisation techniques. This requires a more detailed description of the characteristics of attributes, how it is usual in the field of problem-oriented visualisation. We want to consider the type of attributes [Lang97], the dependencies of attributes from each other [Hibb95] and the properties of ranges [Robe90], [Aren93], [Lang95]. Table 2 summarises the description of attributes. characteristic value type string, integer,... dependency dependent, independent continuity discrete, continuous ordering ordinal, nominal visibility yes, no importance very important, important, informative Table 2: Characteristics of attributes Characteristics of class hierarchy Characteristics of class hierarchy are especially relevant for goal specification and information selection (see 4.2). For example we need to know, which information objects belong to which classes of the information model and what classes of the information model are described by which attributes. Table 3 summarises these characteristics. characteristic value inheritance class subclass class-attributes class attributes Table 3: Characteristics of class hierarchy 4 The Usage of the information model for presentation generation Based on the described information model and its characteristics we will now analyse how it can be used for the process of intelligent presentation generation. Figure 3 shows this process with its basic steps. The whole process of intelligent presentation generation should not be

6 discussed in detail, because our paper focus on the integration of information description. A detailed discussion of presentation generation is given in [Otto98]. Application Media Selection Information Selection Media Realization Context Goal Formulation Media Coordination Figure 3: The process of intelligent presentation generation 4.1 Development of an application-independent format of information to be presented As described above the information model has to be refined application dependent. However, for usage in an intelligent multimedia presentation system it should be defined in an application independent format. This requires the development of an application-independent interface between information model and IMMPS. To realise real flexible response to questions of the user, this interface should include the description and distinction of the elements of information space, which should be presented. These are: information objects, which shall be presented, as a subset of the information set IM, object-object-relations, which shall be presented, belonging to the information structure IS, attribute values, which shall be presented, as a subset of the attribute set AM. Furthermore, some connections between these elements could be interesting. That s why the interface has to describe two additional aspects: information objects with their attributes, which shall be presented, so called object-attributerelations, object-object-relations with their attributes, which shall be presented, so called objectobject-attribute-relations. The characteristics of these information elements, which shall be presented, can be determined by characteristics of the information space as described in chapter 3. Some of these characteristics are probably integrated in the element description and therefore they can be simply taken on (e.g., visibility of a single information object). Some have to be deduced and determined on the fly (e.g., visibility of a set of information object or the number of information elements to be presented ). 4.2 Intuitive goal formulation The first step of intelligent presentation generation is the specification of a question (or goal) by the user. A real problem by using IMMPS is the appropriate specification of a set of questions, which the user can ask the system.

7 The information model described in this paper makes it possible to solve this problem intuitively and problem-oriented under the following assumption: Every question consists of two parts a general and a special part. The general part refers to special classes of the information model and specifies general requirements (e.g., for things other questions are relevant than for processes, for persons other than for books). Every class of the information model can be related to such a set of relevant questions. Figure 4 shows some examples of general parts of questions and their relation to classes of the information model for our library-example. Show %1!, information object How long does %1 know %2?, Person, Person information object thing process term How long takes %1?, process How old is %1?, Person person book Describe the book %1!, book librarian reader What does %1like reading?, Leser Figure 4: General parts of questions for an example The special part asks for concrete information objects according to the class of information model the question refers to (e.g., Gabi if the question refers to the class person ). Questions to be asked by the user according to Figure 4 include How old is Gabi? or Describe BOOKx!. First the user specifies the general part of a question, normally by selecting it from list-boxes (e.g., How old is...? ). After he defined the special part of the question, he specifies an information object (e.g., Gabi ). The system knows, which information objects belong to which classes of the information model and that is why these information objects only can be provided to the user for selection. Depending on the specified question the information to be presented is selected from the information space and transformed in the application-independent format (see 4.1). 4.3 Media selection The task of media selection is the linking of information elements with appropriate media types for presentation. Media selection can be organised as a multi-stage process, influenced by a great amount of different factors (see [Otto98]). An important influencing factor is the characteristic of the information elements, which shall be presented, for example: the class or type (e.g., attribute values could be presented by diagrams or tables, information objects by images, videos or text), the importance ( e.g., important information should be stressed by special media like sound or icons), the visibility (e.g., not visible information can not be presented by video or photography) or number of information elements.

8 4.4 Media realisation While the media selection step associates information elements with media types, the task of the media realisation step is the selection and/or creation of concrete media objects according to the selected media types. The selection of media objects assumes, there exist different media objects (at least one), which are linked with an information element, which shall be presented (e.g. an image about an information object). The connection between information objects and media objects is described by a so-called information content. This information content says which information object is where and how good it is presented by the media object. The information content is the main criterion for the selection of proper media objects for the presentation. The generation of new media objects on the fly is based on the abstract description of information according to our information model. This abstract description makes it possible to integrate various presentation techniques. Attribute values and object-attribute-relations could be treated as equivalent to data in scientific visualisation. Our description of the characteristics of attributes considers this fact. Therefore we can use the results of problem-oriented visualisation for the generation of media objects. 4.5 Media co-ordination During media co-ordination media objects are arranged to achieve the resulting multimedia presentation. This process should consider characteristics of information, which shall be presented too, especially the importance of information objects. That is why it seems to be convenient to place media objects with high importance on stressed positions to get the attention of the user (e.g., in the left upper corner of an window or centred). 4.6 Information related interaction on the presentation While in the field of computer graphics the selection of graphical objects from pictures could be treated as usual, it is generally not possible in multimedia applications. For our approach we defined the information content, which contains the position and characteristics of information objects in a media objects. That means, we are able to select information objects from a media object like a raster image and ask questions about it. This enables dynamic interaction structures and therefore an intuitive usage of the system. 5 An example for using the information model in IMMPS Based on the information model described in this paper an IMMPS was developed, which has been applied in practice. The developed IMMPS is used for an information system in the field of ecology. It presents information about a mobile soil clearing station, its usage, parts, repairing and related knowledge. The information model and its characteristics are stored in a database. The IMMPS was realised according to the standard reference model for IMMPS. It uses various media objects like images, videos and text-descriptions, which are linked with information objects by an information content. Furthermore the system allows the generation of media objects like diagrams, graphs, lists or tables for a flexible presentation generation. Figure 5 shows the developed interface. The left part of the window is used for the specification of questions the right part for displaying the generated presentation. The specification of questions by the user is done by selecting the general and special part of the question from listboxes. Additionally the user can select information objects from the presentation (in the right part of the window), which causes the display of relevant questions in the upper listbox.

9 Figure 5: Interface of the developed IMMPS 6 Conclusion The paper presented a proposal for an information model. We discussed how to use this information model during the presentation generation. That means, we are able to get very flexible presentations appropriate for a given information. Furthermore this approach offers an intuitive way for selecting information by questions and also for selecting information objects from the presentation. A first application in a practical system has been described. 7 References [Andr93] [Aren93] André, E. and Rist, T.: The Design of Illustrated Documents as a Planning Task. In: Maybury, M. T. (ed.): Intelligent Multimedia Interfaces, MIT Press, Massachusetts 1993, pp Arens, Y.; Hovy, E.H.; Vossers, M.: On the Knowledge Underlying Multimedia Presentations. In: Maybury, M. T. (ed.): Intelligent Multimedia Interfaces, MIT Press, Massachusetts 1993, pp [Behm93] Behme, W.: Entwurf eines objektorientierten Meta-Informationssystems zur Unterstützung der Informationslogistik, Dissertation, Hildesheim, 1993 [Bord97] [Brod92] Bordegoni, M. et al.: A Standard Reference Model for Intelligent Multimedia Presentation Systems. Computer Standards and Application of Standards for Computers, Data Communications and Interfaces, 1997 Brodlie, K.W. et al. (eds.): Scientific Visualization - Techniques and Applications, Springer, Berlin 1992

10 [Gers94] [Hibb95] [Lang95] Gershon, N.D.: Informations Visualization: The next frontier, in: Proceedings SIGGRAPH 94, Orlando, Florida, 1994 Hibbard, W.L.; Dyer, C.R.; Paul, B.E.: Interacitivity and the Dimensionality of Data Displays. In: Grinstein, G.; Levkowitz, H. (eds.): Perceptual Issues in Visualization, Springer, Berlin, 1995 Lange, S.; Schumann, H..; Müller, W.; Krömker, D.: Problem-oriented visualization of multi-dimensional data sets. In: Scateni, R. (ed.): Scientific Visualization, World Scientific, Singapore, 1995 [Lang97] Lange, S.: Ermittlung von Wertebereichs- und Schlüsseleigenschaften für Visualisierungsentscheidungen, Preprint CS-10-97, Preprints aus dem Fachbereich Informatik, Universität Rostock, 1997 [Mack86] [Otto98] [Robe90] [Roth93] [Shan76] [Wend91] [Wüns97] [Zhou96] Mackinlay, J.: Automating the design of graphical presentations of relational information. ACM Transactions on Graphics, 5(2): , 1986 Otto, K.; Schumann, H.: Knowledge-Based Multimedia Presentation Generation, submitted for ACIM 98, The 6 th ACM International Multimedia Conference, Bristol, UK, Sep Robertson, P.K.: A Methodology for Scientific Data Visualization: Choosing Representations Based on a Natural Scene Paradigm. In: Proceedings Visualization 90, San Francisco, 1990 Roth, S.F.; Hefley, W.E.: Intelligent Multimedia Presentation Systems: Research and Principles. In: Maybury, M. T. (ed.): Intelligent Multimedia Interfaces, MIT Press, Massachusetts 1993, pp Shannon, C.E.; Weaver, W.: Mathematische Grundlagen der Informationstheorie, R.Oldenburg-Verlag, München, Wien, 1976 Wendt, S.: Nichtphysikalische Grundlagen der Informationstechnik, Springer, Berlin, 1991 Wünsche, Veikko: Information und Präsentation, Diplomarbeit, Universität Rostock, Fachbereich Informatik, 1997 Zhou, M.X.; Feiner, S.K.: Data Characterization For Automatically Visualizing Heterogeneous Information. In: Proceedings IEEE Symposium on Information Visualization 96, IEEE Computer Society Press, 1996