# A Grammar-based Compressed Representation of 3D Trajectories

## TL;DR

This paper introduces 3DGraCT, a novel grammar-based compression method for 3D flight trajectories that significantly reduces storage space while maintaining efficient query performance, aiding air traffic management.

## Contribution

It extends the GraCT structure to handle 3D data, achieving two orders of magnitude space reduction compared to traditional methods.

## Key findings

- Reduces space requirements of trajectory data by 100 times.
- Maintains competitive query performance for 3D flight data.
- Outperforms existing structures in specific query scenarios.

## Abstract

Much research has been published about trajectory management on the ground or at the sea, but compression or indexing of flight trajectories have usually been less explored. However, air traffic management is a challenge because airspace is becoming more and more congested, and large flight data collections must be preserved and exploited for varied purposes. This paper proposes 3DGraCT, a new method for representing these flight trajectories. It extends the GraCT compact data structure to cope with a third dimension (altitude), while retaining its space/time complexities. 3DGraCT improves space requirements of traditional spatio-temporal data structures by two orders of magnitude, being competitive for the considered types of queries, even leading the comparison for a particular one.