### Abstract

We study the amortized number of combinatorial changes (edge insertions and removals) needed to update the graph structure of the Voronoi diagram VD(S) (and several variants thereof) of a set S of n sites in the plane as sites are added to the set. To that effect, we define a general update operation for planar graphs that can be used to model the incremental construction of several variants of Voronoi diagrams as well as the incremental construction of an intersection of halfspaces in ℝ^{3}. We show that the amortized number of edge insertions and removals needed to add a new site to the Voronoi diagram is O(√n). A matching Ω(√n) combinatorial lower bound is shown, even in the case where the graph representing the Voronoi diagram is a tree. This contrasts with the O(log n) upper bound of Aronov et al. (2006) for farthest-point Voronoi diagrams in the special case where points are inserted in clockwise order along their convex hull. We then present a semi-dynamic data structure that maintains the Voronoi diagram of a set S of n sites in convex position. This data structure supports the insertion of a new site p (and hence the addition of its Voronoi cell) and finds the asymptotically minimal number K of edge insertions and removals needed to obtain the diagram of S ∪ {p} from the diagram of S, in time O(K polylog n) worst case, which is O(√n polylog n) amortized by the aforementioned combinatorial result. The most distinctive feature of this data structure is that the graph of the Voronoi diagram is maintained explicitly at all times and can be retrieved and traversed in the natural way; this contrasts with other known data structures supporting nearest neighbor queries. Our data structure supports general search operations on the current Voronoi diagram, which can, for example, be used to perform point location queries in the cells of the current Voronoi diagram in O(log n) time, or to determine whether two given sites are neighbors in the Delaunay triangulation.

Original language | English (US) |
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Title of host publication | 32nd International Symposium on Computational Geometry, SoCG 2016 |

Publisher | Schloss Dagstuhl- Leibniz-Zentrum fur Informatik GmbH, Dagstuhl Publishing |

Pages | 15.1-15.16 |

Volume | 51 |

ISBN (Electronic) | 9783959770095 |

DOIs | |

State | Published - Jun 1 2016 |

Event | 32nd International Symposium on Computational Geometry, SoCG 2016 - Boston, United States Duration: Jun 14 2016 → Jun 17 2016 |

### Other

Other | 32nd International Symposium on Computational Geometry, SoCG 2016 |
---|---|

Country | United States |

City | Boston |

Period | 6/14/16 → 6/17/16 |

### Fingerprint

### Keywords

- Delaunay triangulation
- Dynamic data structures
- Voronoi diagrams

### ASJC Scopus subject areas

- Software

### Cite this

*32nd International Symposium on Computational Geometry, SoCG 2016*(Vol. 51, pp. 15.1-15.16). Schloss Dagstuhl- Leibniz-Zentrum fur Informatik GmbH, Dagstuhl Publishing. https://doi.org/10.4230/LIPIcs.SoCG.2016.15

**Incremental Voronoi diagrams.** / Allen, Sarah R.; Barba, Luis; Iacono, John; Langerman, Stefan.

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

*32nd International Symposium on Computational Geometry, SoCG 2016.*vol. 51, Schloss Dagstuhl- Leibniz-Zentrum fur Informatik GmbH, Dagstuhl Publishing, pp. 15.1-15.16, 32nd International Symposium on Computational Geometry, SoCG 2016, Boston, United States, 6/14/16. https://doi.org/10.4230/LIPIcs.SoCG.2016.15

}

TY - GEN

T1 - Incremental Voronoi diagrams

AU - Allen, Sarah R.

AU - Barba, Luis

AU - Iacono, John

AU - Langerman, Stefan

PY - 2016/6/1

Y1 - 2016/6/1

N2 - We study the amortized number of combinatorial changes (edge insertions and removals) needed to update the graph structure of the Voronoi diagram VD(S) (and several variants thereof) of a set S of n sites in the plane as sites are added to the set. To that effect, we define a general update operation for planar graphs that can be used to model the incremental construction of several variants of Voronoi diagrams as well as the incremental construction of an intersection of halfspaces in ℝ3. We show that the amortized number of edge insertions and removals needed to add a new site to the Voronoi diagram is O(√n). A matching Ω(√n) combinatorial lower bound is shown, even in the case where the graph representing the Voronoi diagram is a tree. This contrasts with the O(log n) upper bound of Aronov et al. (2006) for farthest-point Voronoi diagrams in the special case where points are inserted in clockwise order along their convex hull. We then present a semi-dynamic data structure that maintains the Voronoi diagram of a set S of n sites in convex position. This data structure supports the insertion of a new site p (and hence the addition of its Voronoi cell) and finds the asymptotically minimal number K of edge insertions and removals needed to obtain the diagram of S ∪ {p} from the diagram of S, in time O(K polylog n) worst case, which is O(√n polylog n) amortized by the aforementioned combinatorial result. The most distinctive feature of this data structure is that the graph of the Voronoi diagram is maintained explicitly at all times and can be retrieved and traversed in the natural way; this contrasts with other known data structures supporting nearest neighbor queries. Our data structure supports general search operations on the current Voronoi diagram, which can, for example, be used to perform point location queries in the cells of the current Voronoi diagram in O(log n) time, or to determine whether two given sites are neighbors in the Delaunay triangulation.

AB - We study the amortized number of combinatorial changes (edge insertions and removals) needed to update the graph structure of the Voronoi diagram VD(S) (and several variants thereof) of a set S of n sites in the plane as sites are added to the set. To that effect, we define a general update operation for planar graphs that can be used to model the incremental construction of several variants of Voronoi diagrams as well as the incremental construction of an intersection of halfspaces in ℝ3. We show that the amortized number of edge insertions and removals needed to add a new site to the Voronoi diagram is O(√n). A matching Ω(√n) combinatorial lower bound is shown, even in the case where the graph representing the Voronoi diagram is a tree. This contrasts with the O(log n) upper bound of Aronov et al. (2006) for farthest-point Voronoi diagrams in the special case where points are inserted in clockwise order along their convex hull. We then present a semi-dynamic data structure that maintains the Voronoi diagram of a set S of n sites in convex position. This data structure supports the insertion of a new site p (and hence the addition of its Voronoi cell) and finds the asymptotically minimal number K of edge insertions and removals needed to obtain the diagram of S ∪ {p} from the diagram of S, in time O(K polylog n) worst case, which is O(√n polylog n) amortized by the aforementioned combinatorial result. The most distinctive feature of this data structure is that the graph of the Voronoi diagram is maintained explicitly at all times and can be retrieved and traversed in the natural way; this contrasts with other known data structures supporting nearest neighbor queries. Our data structure supports general search operations on the current Voronoi diagram, which can, for example, be used to perform point location queries in the cells of the current Voronoi diagram in O(log n) time, or to determine whether two given sites are neighbors in the Delaunay triangulation.

KW - Delaunay triangulation

KW - Dynamic data structures

KW - Voronoi diagrams

UR - http://www.scopus.com/inward/record.url?scp=84976891131&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84976891131&partnerID=8YFLogxK

U2 - 10.4230/LIPIcs.SoCG.2016.15

DO - 10.4230/LIPIcs.SoCG.2016.15

M3 - Conference contribution

VL - 51

SP - 15.1-15.16

BT - 32nd International Symposium on Computational Geometry, SoCG 2016

PB - Schloss Dagstuhl- Leibniz-Zentrum fur Informatik GmbH, Dagstuhl Publishing

ER -