GraCT: A Grammar Based Compressed Representation of Trajectories
- Cite this paper as:
- Brisaboa N.R., Gómez-Brandón A., Navarro G., Paramá J.R. (2016) GraCT: A Grammar Based Compressed Representation of Trajectories. In: Inenaga S., Sadakane K., Sakai T. (eds) String Processing and Information Retrieval. SPIRE 2016. Lecture Notes in Computer Science, vol 9954. Springer, Cham
We present a compressed data structure to store free trajectories of moving objects (ships over the sea, for example) allowing spatio-temporal queries. Our method, GraCT, uses a \(k^2\)-tree to store the absolute positions of all objects at regular time intervals (snapshots), whereas the positions between snapshots are represented as logs of relative movements compressed with Re-Pair. Our experimental evaluation shows important savings in space and time with respect to a fair baseline.