A survey on content-based retrieval for multimedia databases <s> Spatio-Temporal Relations <s> An interval-based temporal logic is introduced, together with a computationally effective reasoning algorithm based on constraint propagation. This system is notable in offering a delicate balance between <s> BIB001 </s> A survey on content-based retrieval for multimedia databases <s> Spatio-Temporal Relations <s> Proposes an extension to an earlier proposed temporal synchronization model, called OCPN. The new model allows one to specify spatial operations at the time of authoring the multimedia information. The authors present a mechanism to translate the model into an object-oriented environment. For this purpose the temporal operations are selected as objects. This scheme has many advantages over the existing object-oriented model since it requires fewer number of objects as well as do not limit the users to share the actual raw data. A polynomial time algorithm is proposed to translate the new OCPN into an object hierarchy. > <s> BIB002 </s> A survey on content-based retrieval for multimedia databases <s> Spatio-Temporal Relations <s> This paper presents a framework for data modeling and semantic abstraction of image/video data. The framework is based on spatio-temporal information associated with salient objects in an image or in a sequence of video frames and on a set of generalized n-ary operators defined to specify spatial and temporal relationships of objects present in the data. The methodology presented in this paper can manifest itself effectively in conceptualizing events and heterogeneous views in multimedia data as perceived by individual users. The proposed paradigm induces a multilevel indexing and searching mechanism that models information at various levels of granularity and hence allows processing of content-based queries in real time. We also devise a unified object-oriented interface for users with heterogeneous views to specify quem’es on the unbiased encoded data. Currently this framework is being developed to realize a highly integrated multimedia database architecture. 1 <s> BIB003 </s> A survey on content-based retrieval for multimedia databases <s> Spatio-Temporal Relations <s> Multimedia applications usually involve a large number of multimedia objects (texts, images, sounds, etc.). Spatial and temporal relationships among these objects should be efficiently supported and retrieved within a multimedia authoring tool. In this paper, we present several spatial, temporal and spatio-temporal relationships of interest, and propose efficient indexing schemes, based on multidimensional (spatial) data structures, for large multimedia applications that involve thousands of objects. Evaluation models of the proposed schemes are also presented, as well as hints for the selection of the most appropriate one, according to the multimedia author's requirements. <s> BIB004
Regarding the representation of spatial and temporal relations, there are two alternatives; representing them in a consistent way and representing them independently. Iino et al. BIB002 is an example of the former, where the temporal relation is primary and the spatial relation is secondary. Objects are structured with temporal relations between component objects as proposed in BIB001 , and spatial composition operations such as overlay, overlap, abut, crop, and scale are defined as spatial relations. With this approach, the spatial composition operations are not consistent with the temporal relations, since the spatial composition operations are assumed to be applied to multimedia data presentation. Day et al. BIB003 is another work done by the same research group as BIB002 , where both spatial and temporal relations are based on a single set of interval-based primitive relations. An advantage of this approach is that content based retrieval on both spatial and temporal relation is realized in a unified manner. Theodoridis et al. BIB004 also discussed spatio-temporal indexing of multimedia objects in an integrated manner, where their approach assumes multimedia presentation. With regard to the indexing, two approaches have been proposed: One is separating the spatial index by a 2D R-tree from the temporal index by a 1D R-tree, and the other is integrating spatio-temporal indexing by 3D R-trees. As introduced above, there are not many studies of the spatio-temporal modeling of multimedia data. Whether or not a model provides consistent representation for both spatial and temporal relation depends on the application. There is still room for further discussion. Bimbo et al.  (see Fig. 4 ) presented an interesting method for expressing spatial relations of objects in an image. The system demonstrates the retrieval of a 2D image in terms of giving spatial relations of an object in a 3D space. Though the world projected into photos is a 2D representation, it was originally a 3D space. The method proposed in the literature provides a user with a way to represent spatial relations of objects in a 3D space with a data glove, which is recognized as an example of spatial relations among objects and translated into a 2D representation. Allowing a 3D representation of an example which is close to human's way of memorization is considered to be an effective way of representing an example even for a 2D image retrieval. The QBE with motion example introduced above is concerned with the motion of an object by three elements, namely trajectory, velocity, and size of the object. This is another approach for the retrieval of spatio-temporal contents  . With this approach, an example is regarded as a sequence of spatial relations. A user specifies positions of objects on a screen from which the system extracts spatial relations at a certain point of time. The user defines two or more sets of spatial relations sequentially in accordance with the time, representing spatio-temporal relations of the objects. This approach is not aimed at the retrieval of the detailed motion of an object, but is aimed at spatio-temporal correlation of multiple objects, since the motion of an object is specified on discrete time.