15th ACM GIS: Seattle, WA: Nov 7—9, 2007

TS2-Tree: An Efficient Similarity Based TS2-Tree: An Efficient Similarity Based Organization for Trajectory DataOrganization for Trajectory Data

Petko BakalovEamonn Keogh

Vassilis J. TsotrasUniversity of California Riverside

{pbakalov,eamonn,tsotras}@cs.ucr.edu

15th ACM GIS: Seattle, WA: Nov 7—9, 2007

Similarity queries between trajectory objects are important– What is the number of commuters which have similar trajectories

to the proposed bus line?– Which bus line suits me best for my anticipated trip?

Problem: Traditional methods for trajectory indexing do not preserve the global picture of the trajectory.

In the poster, we present a novel indexing technique TS2-tree which:– Clusters trajectories according to their similarity– Preserves global view of the trajectory– Provides upper and lower bound estimations of the distances between

trajectories

Need for TS2-tree?

15th ACM GIS: Seattle, WA: Nov 7—9, 2007

Trajectory Envelope – a key component in TS2-tree.

Trajectory envelopes are organized hierarchically into a height balanced tree structure similar to an R-tree or B-tree.

– The structure is completely dynamic: The insert and delete operations can be intermixed with search ones.

The similarity search becomes a top down traversal of the tree guided by the upper and lower bound estimations.

More details will be provided in our poster.

TS2-tree structure