Efficient Trajectory Compression and Queries

Nowadays, there are ubiquitousness of GPS sensors in various devices collecting, storing and transmitting tremendous trajectory data. However, an unprecedented scale of GPS data has posed an urgent demand for not only an effective storage mechanism but also an efficient query mechanism. Line simplification in online mode, a kind of commonly used trajectory compression methods in practice, plays an important role to attack this issue. To attack this issue, in this paper, each compressed trajectory is regarded as a sequence of continuous line segments, but not discrete points. And based on this, we propose a new trajectory similarity metric AL, an efficient index \emph{ASP-tree} and two algorithms about how to process range queries and top-$k$ similarity queries on the compressed trajectories.