Immersive virtual environments (VEs)

Due to the ubiquity of space-related and time-related information, the ability of a database system to deal with both spatial and temporal phenomenon facts in a spatiotemporal applications is highly desired. However, uncertain and fuzzy information in these applications highly increases the complexity of database modeling. In this paper we introduce a semantic data modeling approach for spatiotemporal database applications. We specifically focus on various aspects of spatial and temporal database issues and uncertainty and fuzziness in various abstract levels. The semantic data model that we Ž . introduce in this paper utilizes unified modeling language UML for handling spatiotemporal information, uncertainty, and fuzziness especially at the conceptual level of database Ž . design. An environmental information system EIS application is used to illustrate our modeling approach and extension made to UML. By incorporating uncertainty and fuzziness into the semantic data model of a spatiotemporal EIS database application, one can handle pollution summary, analysis, and even pollution predictions, in addition to the other common uses of a database system. ᮊ

No abstract

Current large-scale information sources are designed to support general queries and lack the ability to support scenario specific information navigation, gathering, and presentation. As a result, users are often unable to obtain desired specific information within a well-deJned subject area. Today's information systems do not provide efJicient content navigation, incremental appropriate matching, or content correlation. We are developing the following innovative technologies to remedy these problems: ( 1 ) Scenariobased proxies, enabling the gathering andjltering of information customized for users within a pre-dejned domain;( ) Context-sensitive navigation and matching, providing approximate matching and similarity links when an exact match to a user's request is unavailable; (3) Content correlation of documents, creating semantic links between documents and information sources; ( 4 ) User models for customization of retrieved information and result presentation; and (5)Phrase Indexing for Document Retrieval and Summarization. A digital medical library is currently being constructed using these technologies to provide customized information for the user [SI. The technologies are general in nature and can provide custom and scenario-specific information in many other domains, such as crisis management.