Affiliations: [a] University of Thessaly, Gaiopolis, Larisa, Greece | [b] Universidad Nacional de Colombia, Sede Medellín, Colombia | [c] School of Science and Technology, Hellenic Open University, Patras, Greece
Correspondence:
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Corresponding author: Georgia Garani, University of Thessaly, Gaiopolis 41500, Larisa, Greece. Tel.: +30 2410684597; E-mail: garani@uth.gr.
Abstract: A trajectory is a set of traces left by a moving object. It contains spatio-temporal information about where and when that object was, as well as other semantical relevant information. It is described by a continuation of movement. Data concerning moving objects and their trajectories can be stored in a Trajectory Data Warehouses for organization, managing, and analysis purposes. This work is dedicated to semantic trajectory data warehouses. A logical schema is proposed, called S-TrODW, where an object relational framework is used. The main novelty of the S-TrODW model is the integration of trajectories and their segments in the fact table by means of a nested relation. An algorithm is presented for transforming the flat star schema (with non-nested trajectory segments) to the S-TrODW schema. The proposal is validated through a case study dealing with freight transportation. A more natural modelling and queries formulation, as well as the improvement of query execution time are among the contributions of this paper compared to other works.
