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Supporting Range Queries on Web Data Using k -Nearest Neighbor Search

This paper explores the challenges of accessing geospatial data on the web, particularly for range queries such as nearest neighbor searches. It presents two innovative algorithms: the Quad Drill Down (QDD) and the Dynamic Constrained Delaunay Triangulation (DCDT). These algorithms aim to efficiently find all objects within a specified rectangular region while minimizing the number of k-NN searches required. The paper includes experimental results that demonstrate the effectiveness of these approaches, contributing to improved handling of large volumes of web-based geospatial data.

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Supporting Range Queries on Web Data Using k -Nearest Neighbor Search

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  1. Supporting Range Queries on Web Data Usingk-Nearest Neighbor Search Wan D. Bae, Shayma Alkobaisi, Seon Ho Kim, Sada Narayanappa Computer Science, University of Denver and Cyrus Shahabi Computer Science, University of Southern California W2GIS 2007

  2. Outline • Introduction • Motivation and Approach • Quad Drill Down (QDD) Algorithm • Dynamic Constrained Delaunay Triangulation (DCDT) Algorithm • Experiments • Conclusions W2GIS 2007

  3. Motivation • Large volume of geospatial data available on the web. • Access limited by certain types of queries: • e.g., nearest neighbor queries • Utilize available queries to answer non-supported queries. W2GIS 2007

  4. Range Query Find all McDonalds’ locations in a given rectangular region W2GIS 2007

  5. Range Queries on Web Data using k Nearest Neighbor Search W2GIS 2007

  6. Objective and Approaches Find all objects within a given rectangular query range using a minimum number of k-NN searches • Quad Drill Down (QDD) • Dynamic Constrained Delaunay Triangulation (DCDT) W2GIS 2007

  7. Quad Drill Down (QDD) algorithm W2GIS 2007

  8. Quad Drill Down (QDD) algorithm q1 q2 q q 3-NN search q3 q4 W2GIS 2007

  9. Dynamic Constrained Delaunay Triangulation (DCDT) algorithm W2GIS 2007

  10. DCDT algorithm • A greedy and incremental approach • Use Constrained Delaunay Triangulation (CDT) (a) (b) W2GIS 2007

  11. DCDT 1stk-NN call CDT select uncovered max propagate k-NN call checkCoverRegion W2GIS 2007

  12. DCDT – coverRegion (a) (b) (c) W2GIS 2007

  13. CoverRegion Examples (a) (b) (c) (d) (e) (f) W2GIS 2007

  14. Propagation (a) (b) (c) (d) (e) (f) W2GIS 2007

  15. QDD vs. DCDT vs. N.C. Synthetic data set w/3% range qeury W2GIS 2007

  16. QDD vs. DCDT vs. N.C. Synthetic data set w/3% range qeury W2GIS 2007

  17. Percentage of Coverage Varying k value W2GIS 2007

  18. Conclusions Propose two algorithms to find all objects within a given rectangular query range using k-NN searches: • Quad Drill Down (QDD) • Dynamic Constrained Delaunay Triangulation (DCDT) W2GIS 2007

  19. Thank you! W2GIS 2007

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