Determining Objects within Isochrones in Spatial Network Databases

  • Sarunas Marciuska
  • Johann Gamper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 6295)


Isochrones are generally defined as the set of all space points from which a query point can be reached in a given timespan, and they are used in urban planning to conduct reachability and coverage analyzes in a city. In a spatial network representing the street network, an isochrone is represented as a subgraph of the street network. Such a network representation is not always sufficient to determine all objects within an isochrone, since objects are not only on the network but might be in the immediate vicinity of links (e.g., houses along a street). Thus, the spatial area covered by an isochrone needs to be considered.

In this paper we present two algorithms for determining all objects that are within an isochrone. The main idea is to first transform an isochrone network into an isochrone area, which is then intersected with the objects. The first approach constructs a spatial buffer around each edge in the isochrone network, yielding an area that might contain holes. The second approach creates a single area that is delimited by a polygon composed of the outermost edges of the isochrone network. In an empirical evaluation using real-world data we compare the two solutions with a precise yet expensive baseline algorithm. The results demonstrate the efficiency and high accuracy of our solutions.


Convex Hull Street Segment Range Query Space Point Query Point 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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  1. 1.
    Bauer, V., Gamper, J., Loperfido, R., Profanter, S., Putzer, S., Timko, I.: Computing isochrones in multi-modal, schedule-based transport networks (demo paper). In: ACMGIS 2008, Irvine, CA, USA, November 5-7, pp. 1–2 (2008)Google Scholar
  2. 2.
    Deng, K., Zhou, X., Shen, H.T., Sadiq, S.W., Li, X.: Instance optimal query processing in spatial networks. VLDB J. 18(3), 675–693 (2009)CrossRefGoogle Scholar
  3. 3.
    Edelsbrunner, H.: Weighted alpha shapes. Technical Report:UIUCDCS-R-92-1760 (1992)Google Scholar
  4. 4.
    Edelsbrunner, H., Kirkpatrick, D.G., Seidel, R.: On the shape of a set of points in the plane. IEEE Transactions on Information Theory 29(4), 551–558 (1983)zbMATHCrossRefMathSciNetGoogle Scholar
  5. 5.
    Edelsbrunner, H., Mücke, E.P.: Three-dimensional alpha shapes. In: VVS, pp. 75–82 (1992)Google Scholar
  6. 6.
    Galton, A., Duckham, M.: What is the region occupied by a set of points? In: Raubal, M., Miller, H.J., Frank, A.U., Goodchild, M.F. (eds.) GIScience 2006. LNCS, vol. 4197, pp. 81–98. Springer, Heidelberg (2006)CrossRefGoogle Scholar
  7. 7.
    Gamper, J., Böhlen, M., Cometti, W., Innerebner, M.: Scalable computation of isochrones in bimodal spatial networks. Technical report, Free University of Bolzano-Bozen (2010)Google Scholar
  8. 8.
    Graham, R.L.: An efficient algorithm for determining the convex hull of a finite planar set. Inf. Process. Lett. 1(4), 132–133 (1972)zbMATHCrossRefGoogle Scholar
  9. 9.
    Jarvis, R.A.: On the identification of the convex hull of a finite set of points in the plane. Inf. Process. Lett. 2(1), 18–21 (1973)zbMATHCrossRefMathSciNetGoogle Scholar
  10. 10.
    Moreira, A.J.C., Santos, M.Y.: Concave hull: A k-nearest neighbours approach for the computation of the region occupied by a set of points. In: GRAPP (GM/R), pp. 61–68 (2007)Google Scholar
  11. 11.
    Mouratidis, K., Yiu, M.L., Papadias, D., Mamoulis, N.: Continuous nearest neighbor monitoring in road networks. In: VLDB, pp. 43–54 (2006)Google Scholar
  12. 12.
    Papadias, D., Zhang, J., Mamoulis, N., Tao, Y.: Query processing in spatial network databases. In: VLDB, pp. 802–813 (2003)Google Scholar
  13. 13.
    Zhang, R., Lin, D., Ramamohanarao, K., Bertino, E.: Continuous intersection joins over moving objects. In: ICDE, pp. 863–872 (2008)Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2010

Authors and Affiliations

  • Sarunas Marciuska
    • 1
  • Johann Gamper
    • 1
  1. 1.Free University of Bolzano-BozenItaly

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