RESEARCH AND DEVELOPMENT OF A NULTIMEDIA AND 4 DIMENSIONAL DATABASE SYSTEM

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Multimedia data such as videos and images are often represented and stored in their own file formats. Such data representation makes it difficult and time-consuming to retrieve them by contents. On the contrary, contents of multimedia data are modeled by spatio-temporal data base technologies in our system to accelerate multimedia data retrieval, because spatio-temporal data retrieval is expected to be much faster. From this point of view, we have studied the following.1.A data model for representing and storing spatio-temporal data is designed and implemented. In the model, spatio-temporal data is represented as a subspace in the space resulted from the Cartesian product of spatial, temporal, and non-spatio-temporal attributes. The subspace is represented by a simplicial complex. This representation guarantees that calculation of predicates and operators on spatio-temporal data is carried out in a unified way of combinatorial geometry.2.Spatio-temporal query language is studied by designing a spatio-temporal database and describing spatio-temporal queries. Spatio-temporal predicates are defined as well spatial and temporal predicates. Also, the problem of how spatio-temporal queries are described is studied. In addtion, the transformation of spatio-temporal queries into the queries in the internal representation is studied.3A spatio-temporal index is studied to retrieve them efficiently. The index is implemented based on R^<**>-tree. Spatio-temporal query processing is based on internal representation. This requires query processing on high dimensional spaces. Normalization method of such high dimensional space is studied to accelerate high dimensional spatial data.4.A graphical user interface for displaying spatio-temporal data is implemented using VRML and its browser. Using this interface, a user can understand what the high dimensional spatial data means visually.