A new method to index and store spatio-temporal data
  We propose a data structure that stores, in a compressed way, object trajectories, which at the same time, allow to efficiently response queries without the need to decompress the data. We use a data structure, called $k^{2}$-tree, to store the full position of all objects at regular time intervals. For storing the positions of objects between two time instants represented with $k^{2}$-trees, we only encode the relative movements. In order to save space, those relative moments are encoded with only one integer, instead of two (x,y)-coordinates. Moreover, the resulting integers are further compressed with a technique that allows us to manipulate those movements directly in compressed form. In this paper, we show an experimental evaluation of this structure, which shows important savings in space and good response times. 
Guillermo de Bernardo, Ram\'on Casares, Adri\'an G\'omez-Brand\'on and   Jos\'e R. Param\'a
cs.DS