Visual OLAP analysis on network constrained trajectories

We present RT-Warehouse, a data warehouse that stores aggregated information about trajectories of moving objects travelling on a road network, and allows for interesting visual OLAP analyses. The RT-Warehouse model includes both spatial and temporal dimensions. The spatial dimension reflects the presence of a road network, while the stored measures are concerned with the behaviours of moving objects, in particular objects moving inside a given area during a certain temporal interval, or between areas in the same neighbourhood during given time periods. RT-Warehouse also supplies the user with a visual interface which allows one to easily navigate aggregate measures, obtained from OLAP queries at different granularity levels. RT-Warehouse can be helpful for traffic analysis as illustrated in a case study, where we analyse a large dataset about the movements of cars in the city of Milan (Italy).