Yannis Theodoridis, D. Papadias, and E. Stefanakis. Supporting Direction relations in Spatial database Systems. Proceedings of the 7th International Symposium on Spatial Data Handling(SDH'96), 1996.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....its selection criterion. It is important for a spatial database management system to provide a mechanism for modeling and processing direction queries. Directional relationship is often modeled as a binary relationship between objects[2, 16, 4, 23, 1, 14, 5, 3, 17, 12] Most of the previous work [22, 20, 13] on direction query processing has been focused on indexing mechanisms and processing strategies for queries involving absolute directions(e.g. North, East) A previous study[20] evaluated di erent indices for processing absolute direction queries, and showed that spatial index (e.g. R tree) is ....

....East) A previous study[20] evaluated di erent indices for processing absolute direction queries, and showed that spatial index (e.g. R tree) is ecient for retrieving queries with constraints on both dimensions. Range query strategy(RQS) was used to implement queries involving absolute directions[22, 20, 13]. Since an absolute direction is based on the global reference system, its direction region is an orthogonal rectangle on the global coordinate system. Classical range query strategy is ecient in this case[20] However, object based direction queries are with respect to the orientation of ....

Yannis Theodoridis, D. Papadias, and E. Stefanakis. Supporting Direction relations in Spatial database Systems. Proceedings of the 7th International Symposium on Spatial Data Handling(SDH'96), 1996.

....i.e. the direction is based on the orientation of the viewer, and the third example uses an object orientation based direction as its selection criteria. It is important for a spatial database system to provide a mechanism for modeling and processing direction queries. Most of the previous work [19, 18, 12] on direction query processing has focused on processing predicates of absolute directions(e.g. North, East) using range query strategies. However, object orientation based direction queries and predicates(e.g. left) depend on the orientation of reference objects, which may be di erent from the ....

....A previous study[18] evaluated different indices for processing absolute direction queries. Its results showed that spatial index (e.g. R tree) is ecient for retrieving queries with constraints on both dimensions. Range query strategy(RQS) was used to implement queries involving absolute directions[19, 18, 12]. Since an absolute direction is based on the global reference system, its direction region is an orthogonal rectangle with respect to the global coordinate system. It is ecient to use range query strategy[18] Object orientation based directional queries are based on the orientation of reference ....

Yannis Theodoridis, D. Papadias, and E. Stefanakis. Supporting Direction relations in Spatial database Systems. Proceedings of the 7th International Symposium on Spatial Data Handling(SDH'96), August 1996.

....i.e. the direction is based on the orientation of the viewer, and the third example uses an object orientation based direction as its selection criteria. It is important for a spatial database system to provide a mechanism for modeling and processing direction queries. Most of the previous work [2, 22, 14] on direction query processing has focused on processing predicates of absolute directions(e.g. North, East) using range query strategies. However, object orientation based direction queries and predicates(e.g. left) depend on the orientation of reference objects, which may be different from the ....

....study[22] evaluated different indices for processing absolute direction queries. Its results showed that spatial index (e.g. R tree) is efficient for retrieving queries with constraints on both dimensions. Range query strategy(RQS) was used to implement queries involving absolute directions[2, 22, 14]. For example, consider the query based on the objects in Figure 4: Find all objects that are exactly east of object B. In the context of absolute directions, the x axis and y axis of the coordinate system may be aligned with the East and North directions. The direction queries based on absolute ....

Yannis Theodoridis etc. Supporting Direction relations in Spatial database Systems. 30(10):1249--1257, 1996.

.... efficient one for large data when more than one constraints are involved (e.g. some north and some strictly north for large data files) since R trees are unable to index such data efficiently, but it is sensitive to query size; large query windows are not handled efficiently by composite B trees [36]. 19 5.2. Extensions of KDB trees A similar approach can be considered for KDB trees. KDB trees handle two dimensional data efficiently when the search procedure involves one of the two representative points of the MBRs. However, most of the direction relations involve both points and, as a ....

Y. Theodoridis, D. Papadias, and E. Stefanakis, Supporting Direction Relations in Spatial Database Systems, in: Proc. SDH'96, Advances in GIS Research II (Taylor & Francis, London, 1996).

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