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Implemented Apps
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Implemented ApplicationsThree applications have been implemented in CCUBE: office design, indexing trajectories and spatio-temporal transformations related to vegetation (NDVI) and sea surface temperature (SST) indices. In the office design application, the database contained buildings, rooms, catalog objects such as desk and file cabinets; each such object has an extent, drawers etc. This application was used in the Object-oriented databases class, in which students wrote a range of queries similar to the first example, such as: Given a room and the location of a number of objects in it, can we put an additional desk from the catalog so that its drawer will not touch any other object in the room, and still have an unoccupied 4 ft. ×4 ft. space? What would be the location of the above mentioned objects if we wanted to maximize the size of a square of available empty space? Given a collection of objects in the room, show a projection of their cut at the height of 1/2 ft? Etc. In the students' projects the size of the data was small. Experimentation with large data sets for this application has not been done. Another series of examples was experimentation with the index structures using different "trajectories" example queries, such as the one described previously. In this series the database size ranged from about 50 MB to 1 GB of data involving about 100,000 atomic 4D (conjunctive CST) objects, which composed (disjunctive CST) trajectories. The speed-up of the indexed approximation grouping vs. approximation grouping vs. direct evaluation was very big: a few seconds vs. a few minutes vs. many hours for queries that return small outputs. The experiments are still ongoing and we expect to report on the results and the exact experiment setting elsewhere (when enough results are collected).
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presentation created by Victor E. Segal |