Issue No.05 - May (2010 vol.22)
Sarana Nutanong , The University of Melbourne, Victoria
Egemen Tanin , The University of Melbourne and NICTA Victoria Laboratory, Victoria
Rui Zhang , The University of Melbourne, Victoria
DOI Bookmark: http://doi.ieeecomputersociety.org/10.1109/TKDE.2009.158
In many applications involving spatial objects, we are only interested in objects that are directly visible from query points. In this paper, we formulate the visible k nearest neighbor (VkNN) query and present incremental algorithms as a solution, with two variants differing in how to prune objects during the search process. One variant applies visibility pruning to only objects, whereas the other variant applies visibility pruning to index nodes as well. Our experimental results show that the latter outperforms the former. We further propose the aggregate VkNN query that finds the visible k nearest objects to a set of query points based on an aggregate distance function. We also propose two approaches to processing the aggregate VkNN query. One accesses the database via multiple VkNN queries, whereas the other issues an aggregate k nearest neighbor query to retrieve objects from the database and then re-rank the results based on the aggregate visible distance metric. With extensive experiments, we show that the latter approach consistently outperforms the former one.
Geographical information systems, spatial databases, query processing.
Sarana Nutanong, Egemen Tanin, Rui Zhang, "Incremental Evaluation of Visible Nearest Neighbor Queries", IEEE Transactions on Knowledge & Data Engineering, vol.22, no. 5, pp. 665-681, May 2010, doi:10.1109/TKDE.2009.158