## Effective Density Queries on Continuously Moving Objects (2006)

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Venue: | In ICDE |

Citations: | 18 - 2 self |

### BibTeX

@INPROCEEDINGS{Jensen06effectivedensity,

author = {Christian S. Jensen and Dan Lin and Beng Chin and Ooi Rui Zhang},

title = {Effective Density Queries on Continuously Moving Objects},

booktitle = {In ICDE},

year = {2006},

pages = {71}

}

### Years of Citing Articles

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### Abstract

This paper assumes a setting where a population of objects move continuously in the Euclidean plane. The position of each object, modeled as a linear function from time to points, is assumed known. In this setting, the paper studies the querying for dense regions. In particular, the paper defines a particular type of density query with desirable properties and then proceeds to propose an algorithm for the efficient computation of density queries. While the algorithm may exploit any existing index for the current and near-future positions of moving objects, the B x-tree is used. The paper reports on an extensive empirical study, which elicits the performance properties of the algorithm.

### Citations

339 |
Discrete Cosine Transform; Algorithms, Advantages and Applications
- Rao, Yip
- 1990
(Show Context)
Citation Context ...red on disk, substantial I/O is needed to maintain it and use it during query processing. Therefore, it is critical to reduce the size of the DH. We propose to use the Discrete Cosine Transform (DCT) =-=[13]-=- for compression. The detailed algorithm and analysis are as follows. 4.2.1 Histogram Construction For each cell, the number of objects in the cell varies across time, but the number is not likely to ... |

319 | Indexing the positions of continuously moving objects
- Saltenis, Jensen, et al.
(Show Context)
Citation Context ...ts that supports predictive window queries may be used by our proposal for computing the density query. Representative indexes include the TPR-tree (Time-Parameterized Rtree) family of indexes (e.g., =-=[14, 15]-=-) and transformationbased indices such as STRIPES [12], which supports efficient updates and queries at the expense of higher space requirements, and the B x -tree [4], which uses the B + -tree to man... |

147 | The TPR*-tree: An optimized spatio-temporal access method for predictive queries
- Tao, Papadias, et al.
(Show Context)
Citation Context ...ts that supports predictive window queries may be used by our proposal for computing the density query. Representative indexes include the TPR-tree (Time-Parameterized Rtree) family of indexes (e.g., =-=[14, 15]-=-) and transformationbased indices such as STRIPES [12], which supports efficient updates and queries at the expense of higher space requirements, and the B x -tree [4], which uses the B + -tree to man... |

67 | STRIPES: An efficient index for predicted trajectories
- Patel, Chen, et al.
(Show Context)
Citation Context ...our proposal for computing the density query. Representative indexes include the TPR-tree (Time-Parameterized Rtree) family of indexes (e.g., [14, 15]) and transformationbased indices such as STRIPES =-=[12]-=-, which supports efficient updates and queries at the expense of higher space requirements, and the B x -tree [4], which uses the B + -tree to manage moving objects efficiently. We employ the B x -tre... |

60 | Query and update efficient B+-tree based indexing of moving objects
- Jensen, Lin, et al.
(Show Context)
Citation Context ...e) family of indexes (e.g., [14, 15]) and transformationbased indices such as STRIPES [12], which supports efficient updates and queries at the expense of higher space requirements, and the B x -tree =-=[4]-=-, which uses the B + -tree to manage moving objects efficiently. We employ the B x -tree as our underlying index structure. Several proposals [9, 10, 11] exist for the computation of spatio-temporal a... |

55 | The Effect of Buffering on the Performance of R-Trees
- Leutenegger, Lopez
- 2000
(Show Context)
Citation Context ...ment. Figure 11. Refinement algorithm We employ the B x -tree [4] as the index for the refinement phase. It has three phases and a node capacity of 200 entries. An LRU page buffer of 50 pages is used =-=[5]-=-, with the internal nodes of a tree being pinned in the buffer. The space domain is 1000 × 1000 units. The datasets are generated using an existing data generator, where objects move in a network of t... |

45 | Spatio-temporal access methods
- Mokbel, Ghanem, et al.
(Show Context)
Citation Context ...management foundations that enable the provisioning of efficient services. Proposals exist for the efficient computation of, e.g., window queries and nearest neighbor queries on moving objects (e.g., =-=[7, 8]-=-). In this paper, we study the querying for dense regions, regions with a high concentration of moving objects. The objective is to find regions in space along with associated points in time where the... |

42 | Clustering Moving Objects
- Li, Han, et al.
- 2004
(Show Context)
Citation Context ... Existing clustering algorithms can represent the most dense areas by, e.g., the centers of the clusters. As good examples, Yiu and Mamoulis [16] cluster objects at a certain timestamp; and Li et al. =-=[6]-=- cluster moving objects, but at the expense of high maintenance costs. These techniques do not meet the requirements posed by density queries. They are unable to identify those regions with a density ... |

40 | Efficient OLAP operations in spatial data warehouses
- PAPADIAS, KALNIS, et al.
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Citation Context ...xpense of higher space requirements, and the B x -tree [4], which uses the B + -tree to manage moving objects efficiently. We employ the B x -tree as our underlying index structure. Several proposals =-=[9, 10, 11]-=- exist for the computation of spatio-temporal aggregation queries, which are similar to density queries in some sense, since density queries also need to know the numbers of objects inside certain ran... |

39 | Indexing spatio-temporal data warehouses
- Papadias, Tao, et al.
- 2002
(Show Context)
Citation Context ...xpense of higher space requirements, and the B x -tree [4], which uses the B + -tree to manage moving objects efficiently. We employ the B x -tree as our underlying index structure. Several proposals =-=[9, 10, 11]-=- exist for the computation of spatio-temporal aggregation queries, which are similar to density queries in some sense, since density queries also need to know the numbers of objects inside certain ran... |

28 | Efficient Tracking of Moving Objects with Precision Guarantees
- Civilis, Jensen, et al.
- 2004
(Show Context)
Citation Context ...at representing positions as linear functions of time reduces the numbers of updates needed to maintain a reasonable accuracy by as much as a factor of three in comparison to using constant functions =-=[2]-=-. Linear functions are thus much better than 2 constant functions. Third, several indexing techniques exist that index this representation and which can be reused. With this general data setting in pl... |

28 | Range aggregate processing in spatial databases
- TAO, D
(Show Context)
Citation Context ...xpense of higher space requirements, and the B x -tree [4], which uses the B + -tree to manage moving objects efficiently. We employ the B x -tree as our underlying index structure. Several proposals =-=[9, 10, 11]-=- exist for the computation of spatio-temporal aggregation queries, which are similar to density queries in some sense, since density queries also need to know the numbers of objects inside certain ran... |

22 |
Clustering objects on a spatial network
- Yiu, Mamoulis
- 2004
(Show Context)
Citation Context ...ries must locate ranges that satisfy the density threshold. Existing clustering algorithms can represent the most dense areas by, e.g., the centers of the clusters. As good examples, Yiu and Mamoulis =-=[16]-=- cluster objects at a certain timestamp; and Li et al. [6] cluster moving objects, but at the expense of high maintenance costs. These techniques do not meet the requirements posed by density queries.... |

20 | On-Line Discovery of Dense Areas in Spatio-temporal Databases
- Hadjieleftheriou, Kollios, et al.
- 2003
(Show Context)
Citation Context ...gement systems, density queries may be used for identifying regions with potential for congestion and traffic jams. Density querying for moving objects was first considered by Hadjieleftheriou et al. =-=[3]-=-. They define the Region Density as: density(R, ∆t) = min∆t N/area(R), where min∆t N is the minimum number of objects inside R at any time during ∆t and area(R) is the area of R. They define the Perio... |

11 |
Frequent Update and Efficient Retrieval: An Oxymoron on Moving Object Indexes
- Ooi, Tan, et al.
- 2002
(Show Context)
Citation Context ...management foundations that enable the provisioning of efficient services. Proposals exist for the efficient computation of, e.g., window queries and nearest neighbor queries on moving objects (e.g., =-=[7, 8]-=-). In this paper, we study the querying for dense regions, regions with a high concentration of moving objects. The objective is to find regions in space along with associated points in time where the... |